Dismiss the Myths: Fly Control on Equine Facilities

- Client Extension Specialist here at Penn State.

I have with me on the Equine Team, Laura Kenny, an educator in Montgomery County, and Bethany Bickel, an Extension Associate here at University Park with me.

Before I introduce our speaker for the day, just a couple of house housekeeping items.

So, along the bottom of the Zoom box, there are a couple different icons that you can click on.

So, if you have a question during the talk or at the end, please use the Q&A icon to enter your question, that just helps us keep track of questions a little bit more easily.

There is also an option for chat, so I don't know, you know, if the speaker asks you all a question or you just have a general comment on the topic being discussed, you can enter that into the chat box.

We are recording the webinar, and we'll post this on the Penn State Extension Equine website within the next week or so, so you don't have to frantically take notes.

If you wanna go watch this later, it will be available for free on our website.

We do also have on the Extension website quite a few recorded webinars at this point, covering a wide range of topics from facilities to we just had one on toxic plants to nutrition.

So, if you are looking as the weather's getting cooler and you're maybe indoors a little bit more for something to watch to learn about horses, we have quite a few webinars.

I know we have Dr. Machtinger at least one other, I think on ticks on our website, so definitely check those out and we will share the link in the chat with you.

If you want to get updates about future webinars and programs, you can sign up for our email list by either going to the website.

You can also follow us on Facebook if you search for Penn State Extension Equine Team, we share the same information in both locations, so you're never missing out if you only do the Facebook or only do the website.

And we do have a webinar coming up, our next one will be in October, October 17th on commercial feeds and selecting the best ones for your horse.

So, if you're interested in that one, we will have, again, you can register for that now.

One final comment.

At the end of the webinar, we will have a very short evaluation, should take you no more than like two minutes to fill out, and we do appreciate feedback to know what future topics you'd like to hear about.

So, at the end of the webinar, we will share that link with you and I will remind you about that as well.

But for today, our speaker we have is Dr. Erika Machtinger.

So, she is a colleague of ours here at Penn State, she's an Associate Professor of Veterinary Entomology, basically our guru on ticks and flies and all the creepy crawly things that we might see on horses.

So, I'm gonna go ahead and turn it over to Dr. Machtinger.

- Thank you so much.

I am really excited to be here talking about one of my favorite things, which is horses, and one of nobody's favorite things, which is flies.

But as horse people, we have a good deal of experience with both.

So, I'm glad I can be sharing some of this information with all of you, especially this time of the year when we're starting to see a lot of fly issues.

Make sure I can move my cursor here.

So, a little bit about me.

As Dr. Smarsh mentioned, I am a Associate Professor of Veterinary Entomology at Penn State.

I am not a veterinarian, but I do work with parasites basically on non-human vertebrates.

So, horses are one of the animals that I work with, they do a lot with wildlife, a lot with poultry.

But I wanted to give myself a little bit of street cred, that I've been riding for decades now, been around horses, I've evented, I've done dressage, I have had my own farm.

So, much of what I talk about when I talk to the equine community has at least some basis in some of my own experiences, it's rooted in my own experiences dealing with, in this case, flies or with ticks and then augmented by my knowledge and the science behind fly control.

So, what we're gonna talk about is I've been in your shoes if you're dealing with flies, and I've been able to kind of put together tools that we can use to address the problem.

So, today the group of flies that we're gonna talk about are called filth flies.

And they're exactly what it sounds like, they're filth flies, they live in filth, they breed in organic matter, decomposing organic matter like hay or spilled feed, soil bedding, manure, sometimes even grass clippings.

And in horse farms in the northeast, there are four primary species of filth flies that we're gonna talk about.

But it's important to recognize that some of these don't actually reproduce on horse farms.

So, even though you may have some of these species, it may not be your fault that you have them, whereas some, there are some things you can do on your farm to help prevent them from reproducing, and we're gonna talk about that in a minute.

But I also wanted to add that some of you may be here because you are interested in mosquitoes, or biting midges, or horse and deer flies, and unfortunately, we don't have the time to dedicate to all of those species today, recognizing that they are also problems on horse farms.

Extension does have some resources available for those groups specifically, but what I can tell you is how we're approaching filth fly control and how I'm gonna take you through this is really applicable to those other species as well with just some tweaks in knowing how to monitor and knowing different control methods.

So, if that's why you're here, this is still important to learn, and feel free to reach out to me if you have any questions that are more specific to those groups.

So, I'm gonna assume that most you are here because you have either a current problem with flies or have had problems with flies in the past.

And I get asked a question that why are there so many flies?

Especially on my farm, it seems like everybody's farm is a hotspot for flies.

And part of that is because the flies that we're talking about have developed to be really successful in human areas.

So, in the farm situation where we're concentrating animals in small places or when we have additional trash and debris, they do really well and then they also can reproduce really quickly.

So, I've actually been showing this figure for many years, but basically if you start with one female fly in June, by August 1st, you're gonna end up with about 300 million flies.

So, if you had two flies, you're at 600 million and so on.

Now, obviously there's other factors in there, there's predators, there's environmental issues that keep populations from just absolutely taking over the world.

But the bottom line is that if you do nothing to control the population of flies before they become a problem, they are going to be a problem.

So, we have a lot of flies because flies can breed really fast and we provide them areas to reproduce, so we have to approach control thinking about that.

Now, most of us know flies are annoying, and that kind of is what triggers us often to start doing anything about the fly populations as we see our horses upset by them, or a fly lands in our coke that we brought to the barn, or whatever the case may be.

But there's usually some trigger point in our mind that goes, "This is a problem that we need to fix." But other than flies being an annoyance, there are actually some physical and behavioral concerns associated with flies that we should take into account as well.

So, fly pressure with horses can cause reductions in energy, horses are trying to avoid the flies, they can have physical changes, so increases in cortisol levels from the stress, so it's a stress hormone.

Flies can have painful bites that cause irritation.

Foals may be unable to nurse from their meres if they're constantly moving around.

And some of us have probably had that one horse that just can't tolerate the flies and starts walking the fence line or running around a pasture because of the fly pressure.

So, other than just you see your horse's tail swishing or you end up with a fly in your coke, there can be some pretty significant physical changes.

And there's also some concerns from a pathogen level as well.

So, flies are what we call mechanical vectors, so they're really good at picking up pathogens from something like manure and moving it somewhere else.

So, house flies can pick up salmonella, can pick up E.coli, move it from a pile of manure and drop it on your sandwich, which obviously isn't good.

But there are some other things directly related to horses that can be a problem as well.

So, house flies in particular are pretty good at picking up the bacteria that causes pigeon fever, and that's a pretty big concern in the South, but it can be found anywhere.

And then, they also can cause hypersensitivity or pruritus, which means itching, but it's more than just, "Ow, I got bitten, I'm gonna scratch," it's more of a persistent and painful condition that may require veterinary intervention.

And they can also transport around Habronema worms, also called stomach worms.

But when they're on the outside of the horse, they can cause these open wounds, which are called summer sores.

So, flies are moving those or can move those around different locations as well.

So, flies are bad.

So, anytime we talk about bad pests, especially with established pests like flies, we wanna approach it in what is called integrated pest management, or IPM.

So, what is IPM?

So, basically, IPM is a common sense way to approach pest management that uses a variety of methods in an integrated way to address the pest problem while minimizing risks to the health and safety of people, animals, and the environment, but maximizing control.

And that seems like a pretty good idea, right?

It seems like, "Well, of course we do that," but it's a little bit more complicated and a little bit more time consuming than just going to grab a bottle of whatever insecticide off the shelf or whatever repellent off the shelf, it takes a little bit of time to plan and a little bit more knowledge than your rented Tractor Supply and see what they've got plan.

So, what I'm hoping is that I can take everybody through IPM for flies today so you have a better understanding of how you can approach your pest problem from this IPM perspective.

So, IPM breaks down into a series of steps, and it depends on who you talk to how many steps that actually is.

Some have way more steps than is necessary, some have pretty few steps.

For flies, it ends up being kind of six basic steps.

It starts with identifying your pest, but you can see it's circular so it's a constant evolution of a plan.

But basically you gotta start knowing what your pest is, knowing a little bit about that pest, understanding kind of your levels of the pest on your farm, how much you can tolerate, which methods of control are appropriate for your situation, and then evaluating whether what you did actually worked.

And then, it takes you back around, if it didn't work, maybe you have the wrong pest.

If it did work great, you don't have to do a whole lot.

So, it's a cycle of constant modification to make sure you're optimizing your control.

Now, it sounds a bit detailed, it doesn't have to be, and we're gonna go through pieces of that.

One of these we're not gonna talk too much about today, and that is tolerance level because for non-crop-based IPM, it's more of an art than a science.

So, when you deal with something like pests of corn, if they destroy the corn, obviously there's an economic loss, and tolerance level is usually based on if I'm spending more to control it than it's economically worth.

It's not necessarily what we do when we talk about companion animals like horses.

So, tolerance is more how many of these pests can you tolerate on your farm or around the horse.

Now, before you jump around and say, "Zero," recognize that zero is usually a pretty unattainable number when it comes to flies.

So, it needs to land, tolerance needs to land somewhere between the low levels of pests where it's close to zero but maybe not zero, and somewhere where would be high enough for you to recognize that the pests are a problem.

So, it's that level where you find that you can handle it, clients at your farm can handle it, your horse can handle it, but you're not spending too much money to continue to suppress the levels below what they really won't be able to attain.

So, you need to think about that a little bit to understand what that level is.

All right, now the tolerance is out of the way, we're gonna start at the top, which is knowing what pest or pests you actually have on your farm.

This is complicated, and I understand and recognize that folks without a background in entomology may not know where to start as far as understanding which fly you actually have.

So, my goal today is to give you some key characteristics of these flies to help you narrow down what exactly your pest is.

But why am I doing that?

So, I get questions about, "Okay, why do I need to ID the pest if I can go out and buy some chemicals or if I see a fly, I know it's a fly, why do I have to know which fly it is?" And that's a really good question and it is important to understand why you're trying to figure this out.

It's important to know which pests you're targeting because even if they look really similar, different pests do require different control methods.

So, it doesn't help to apply control to like horse manure if the pest you're trying to target doesn't actually develop at horse manure.

So, you wanna make sure that you're using your money wisely basically.

Also, not every fly is a filth fly.

So, you may have problems, as I mentioned, with mosquitoes or biting midges or deer and horse flies, they're not filth fly pests, their biology is very different, where they develop is very different.

So, their control and monitoring is going to be very different as well.

And then, not every fly is a pest.

So, you may see lots of flies around your farm and they're not all pests.

So, if you look at these images here, some of these you may have seen before.

So, in the top left, it's called a bottle fly, and they look an awful lot like filth flies, but these guys are metallic green or metallic blue and they're pollinators and they're decomposers, and you may see them hanging around a trash can because we've put out something that smells good to them in the trash can, but they're not really pests of horses.

So, when you hang up jug traps to try and catch a lot of the pests, the house flies and the face flies that we're gonna talk about in a minute, you may actually end up catching a lot of these guys.

And these are the good guys, we want these guys around.

Crane flies in the top middle, also called mosquito hawks or mosquito killers, they look an awful lot like mosquitoes.

They actually don't have mouth parts, they don't eat anything as adults, they emerge and are completely worthless, so they fly around, lose a bunch of legs, but they are not pests.

Top right is called a dung fly.

So, while you may see these flies on horse manure, they actually are decomposers, so they're also the good guys.

And in the bottom we have a soldier fly, which looks like a wasp, but it is a fly and they're great decomposers, absolutely wonderful, they've been commercialized to help with trash decomposition and waste decomposition, so they're definitely good guys.

And then, you've got this one in the bottom middle, which is called a flesh fly, which is probably a poor name because it has nothing to do with flesh, but they're also decomposers, also pollinators.

And so, we don't wanna be trying to mess with those guys either.

So, not every fly, even if it kind of looks like your pests, is a pest, and we have to keep that in mind.

But when we talk about pests, we do have some, and these are the four that we are going to consider our pest filth flies.

These are the house fly, stable fly, horn fly, and face fly.

And just looking at these, I'm sure all of you are thinking, "How the heck am I gonna tell the difference between these four very gray, bland looking species of flies?" And I'm not gonna ask you to be able to look at them and count lines on them or anything crazy like that, I'm gonna give you some behavioral tips from what your horses are doing to what the flies are doing that I hope can help you categorize them.

So, we're gonna start with house flies.

House flies are the most common pests you're gonna see on your farm.

One of the characteristics is that you can find them both indoors and outdoors and also on your animal and off your animal.

Wherever they're resting, whether it's on your horse or off your horse, they tend to hold their bodies parallel to that surface.

But they're one of the only pest flies that you will find indoors consistently.

So, if your horse is stabled inside and you have a lot of flies inside, likely it's going to be house flies.

Stable flies are one of our biting flies.

So, if you see your horses in the pasture and they're stomping a lot, or they're throwing their head, or rubbing their legs with their nose, or swishing their tail, it's likely because of stable flies.

They love to feed on the legs of horses, so that's why they stomp.

Stable flies when they rest, so they come in, they take a quick blood meal from the horse and then they go rest somewhere else, so you're not gonna see a whole lot of them hanging out on the horses.

So, they're gonna rest on a fence line or the side of a building or something.

But they don't actually like to go into the stable, so it's actually they're misnamed, they won't really hang out inside.

They may come just inside the doorway, especially if there's some light there.

So, if you've got a horse on the cross ties and your farriers is right there by the door, they may be stomping and irritated by stable flies, but just right in that location.

Usually, they're not gonna come in and mess with horses in stalls because they don't like it inside.

So, look for stomping horses and horses really irritated by being bitten on their legs.

Okay, face flies can be really, really challenging to tell apart from house flies.

I put a picture here 'cause this is one of the defining characteristics is their eyes are a little closer together than house flies.

And nobody's gonna be able to tell those differences, it's even hard for an experienced entomologist to get a sample of this and be able to tell that this is a face fly versus a house fly.

I'm not gonna ask anybody to do that.

The key here is that face flies are found almost exclusively outdoors.

So, if you don't have a really big problem with flies inside your stable, but your horses still have flies all over them outside, it may be face flies.

And they're usually found in really high numbers.

So, you see this picture on the top right where the face is just covered with flies and it's almost exclusively on the face, you're not gonna see them on other areas of the body.

Okay, this is one of our flies that does not develop in horse manure, so this is exclusively breeding in cattle manure.

That doesn't mean if you don't have cattle, that doesn't mean that you don't have these flies, they can fly miles away from where they did develop.

It probably means you have cattle somewhere, you know, within 25 miles of you.

But it's one of those where you have to know a little bit about it, that it doesn't breed in horse manure to help control it.

And then horn flies, horn flies are another species that's gonna hold its body parallel, but they're only gonna be found on the horse.

So, they are typically found on the barrel, along the spine near the withers, kind of clumped, as you can see in these pictures.

They're a little bit smaller than the other fly species.

Size isn't a great indicator, but if you look at a bunch of flies and they seem a bit smaller and they're kind of on the back or sides of the horse, it's probably horn flies.

These are another biting fly.

So, if you see your horse twitching a lot, it's probably horn flies that are causing that.

Again, this is another species that breeds exclusively in cattle manure, but you can get these flies coming in as they migrate to other locations or new locations, they accidentally end up on horses.

So, those are the four species.

Now, we have to learn a little bit about them to understand how IPM kind of factors into their control.

So, all flies have what's called complete metamorphosis, which is like a butterfly, which basically means they go through four different life stages: egg, larvae, pupae, and adult.

And this is important to understand just on this basic level because the purpose of IPM is to try and attack these flies at different places in that lifecycle.

So, trying to break it up either between adult and egg, or larvae and pupae, or pupae and adult, so you have maximized control using these different methods.

In terms of how long it takes for them to develop, face and horn flies, again, don't develop an equine manure so it's not necessary for us to go through that.

But for house and stable flies, stable flies develop in about three weeks or so, so they take a little bit longer.

So, you're not usually gonna see really high populations quickly, whereas house flies can have a new generation every seven days or so.

So, if there's good opportunities for flies to develop on your farm, you could see a lot of flies very quickly.

And again, our focus with IPM is to know a little bit about those life cycles so we know we can break it in multiple places.

Monitoring, so this is the third step of IPM and often probably the most overlooked or most forgotten step.

And I get questions like, "Why do I need to monitor the pests?

I can see we have flies.

Why should I write down how many flies we have?

Why do I need to do this?" And the purpose of monitoring is to really get an understanding about what's going on on your farm.

So, are those numbers going up?

Are they going down?

Did the control that you spend a lot of time figuring out what to put down and you spent money on, did it work?

If populations are still increasing and you're putting control down, maybe you don't have the same pest that you thought you had.

So, our eyes are really bad at telling us the truth, right?

So, we've all been in that situation where we see a friend we haven't seen in like three years and they've lost a whole lot of weight and it's shocking 'cause you can see that difference from when you last saw them.

But if you're with somebody over that same period of time, you're not gonna notice those gradual changes, and that's the same thing on farm.

So, when you're in it, you may not notice that what you're doing is working or not working unless you keep track of it.

So, some places that we can look for places where flies may be developing, something like this, which is in a wash rack.

So, if you, if you have a muck bucket in a wash rack, they may be developing in there.

Debris, especially if the floor gets wet around doors or stalls.

Under trailer mats, this is a really good place, even if you clean up the top of it, there can be still wet debris underneath.

Manure piles, you may see flies developing or adult flies.

This is one of the biggest defenders.

So, hay bale rings, so if you've got large round bales, square bales, or if you put out hay in the same spot and you get that waste hay, flies do so well in that.

And then, obviously if you have cattle.

So, keep in mind, even if you don't have cattle, like I mentioned before, that doesn't mean you won't have the cattle-associated flies.

But if you do have cattle, then a lot of those issues are coming from their waste.

So, how do we monitor?

For house flies, there's a couple ways you can monitor.

There's something called a spot card.

So, it's basically a white index card that you put up where you're seeing flies.

You can also use fly ribbons and jug traps, which I mentioned before.

So, you place those in areas where you see flies frequently.

And the key here is that you are counting flies in a consistent manner.

So, I have down here count and replace every seven days.

That's minimum just 'cause that accounts for the biology of the fly turning over every seven days or so.

But if you wanted to do it and count every one day 'cause you wanted to count less flies or every two days, that's perfectly reasonable.

The goal is that you're just making notes about consistent counts so you can track those numbers.

So, if you're like, "Every Monday I'm gonna count this," that would be perfectly reasonable.

For stable flies, those same monitoring devices will not work for stable flies because of how they find their hosts and they don't use odors, they use eyesight.

So, there are two traps that we can use for stable flies, one's called the night stick and one's called the bite-free trap.

And these traps are sticky traps.

And so, the key with these is to make sure they're protected from your horses in some way.

It's always not a fun day when you show up and your horse has a sticky trap stuck to the side of its head.

But you do wanna place these where the flies are going to be, which remember I said they land on fence lines often or around buildings.

So, if you're seeing your horses stomp and you can put it there by that fence line, that's great.

If you want it inside the pasture, just think about adding like a small electric fence around it or something like that to help keep your horses away.

You don't have to use traps, so you can do something even more simple, which is called body counts or behavior counts where you go and you count what a horse on your farm is doing.

And so, you could count stomps, like the number of times they stomp in a one-minute interval or the number of times they shake their head or swish their tail, and you could compare that to previous numbers.

And the key again with this is to be consistent, so if you do it you know every seven days in the morning, make sure that your counts are going to be in the morning moving forward or in the afternoon moving forward because the flies also change their behavior depending on the time of day.

And you also wanna make sure you're doing it on the same horse.

Some horses are more tolerant than other horses in flies, so you wanna make sure you're comparing apples to apples.

So, the key with monitoring is just to be consistent.

With face flies and horn flies, you can do counts as well.

So, face flies tend to make horses shake their head a lot, so that's a behavior that you could use as a metric.

And horn flies, like I said, make horses twitch a lot, and so you could use that as a metric.

So, you know, depending on which species you have, you could use any of those behaviors.

Okay, now control.

So, the meat of what we're really here for is how do we deal with these flies?

So, when we talk about IPM control, there are four different types of control categories, if you will, and they're usually presented in this pyramid form.

So, they start with cultural control and sanitation, mechanical and physical control is above that, bio control, biological control, is above that, and then chemical control is the top.

And you, can see that these different methods start at the bottom, you're really focusing on prevention and at the top it's more intervention.

And then as you go from bottom to top, you have increased risk.

So, that doesn't mean it's risky, it just means it's increased risk.

So, it's easier to prevent a fly from developing in the first place than it is to kill with a chemical.

It's less risky to break up manure than it is to release a biological control method.

So, you just wanna keep that in mind that just because bio control and chemical control have increased risk doesn't mean that we say don't use them, it just means that we use them in a planned and judicious way to make sure we are maximizing our control methods and minimizing those risks.

So, let's look at a few cultural control methods.

So, cultural control is making the environment less suitable for a pest.

Usually, this is breaking the lifecycle by not permitting flies to lay eggs or making the environment inhospitable for eggs so they dry out and die.

And these can be really simple things, so it could be like putting up hay rings so you don't have all that waste hay, or just cleaning up the waste hay so you don't have the waste hay.

It could be something like making sure that your wheelbarrows and muck buckets are dumped multiple times a week so you're interfering with that fly lifecycle.

It could be something like bedding choices.

So, bedding type may change how hospitable an environment is for flies.

And that can be seen here, it's a really good example how something that simple can work.

So, this was a study that was done, I guess it's like 30 years ago now, but basically the flies haven't changed so it's okay.

So, when straw and shavings were compared, they had similar numbers of flies developing, but when they changed the bedding to sawdust, they saw a 45% reduction in house fly numbers and a 91% reduction in stable fly numbers.

And when they changed that bedding to sand, they saw 76% and 100% reduction respectively.

I know people aren't gonna go out and replace their bedding with sand, I can't even imagine trying to clean that out on a daily basis in stalls.

But it could be useful to think about for like run-in sheds or something we're keeping that sandy bedding or sandy flooring instead of having kind of smooshed feces and organic debris could make a difference in fly development.

Another cultural control method is to reduce the pH of that bedding, so lower pHs are less suitable for larval development.

For example, this is a product, it's called sodium bisulfate and I believe on the market it's marketed as ParlorPal, there may be other companies as well.

But it's an additive, so it's kind of like lime, when you clean your stalls you can add this to the the floor and it can reduce the pH, so it makes it less hospitable for fly development.

And when this was added to horse stalls, they found about a 50%.

These are two different farms I did this to, about a 50% reduction in flies just by adding this bedding additive.

So again, IPM, we're not looking for silver bullets, there's nothing that's gonna just take out all the flies, but the idea is that when you have multiple things that you're using, that you have this additive effect of fly control.

So, mechanical and physical control is that second block on the pyramid, and this means you're disrupting the pest activity with some mechanical or physical means.

So, that could be as simple as using a fly swatter to swat the flies or a little bit more complicated like exclusion from development habitat by putting a tarp over your manure pile.

Right, so you're keeping the flies away from where they wanna lay eggs by covering it.

Excluding the flies from your horses, so you're preventing them from taking a blood meal if they're biting flies or sipping on fluids if they're house flies by covering your horse in their vulnerable areas, or using something like a manure spreader to disrupt manure on the fields.

This can prevent flies from developing because there's not enough organic material when it's spread out to have enough nutrients for them to develop.

So, these are pretty, in some cases can be routine, if you already spread manure, that's great.

Some are pretty easy like adding fly sheets, most of us probably do that anyway, and some may not take a whole lot like adding the tarp.

Now, bio control, there's really only two options available for biological control of flies.

Bio control is the use of natural enemies to manage the pest of interest.

And some of you may have seen at least one of these which is the use of parasitoids, and there's a really good body of literature behind using parasitoids for fly management.

The other option is the use of entomopathogenic fungi, which is insect-specific basically fungi that attacks the pest and kills it.

But there's only one product in the market currently and it's a little challenging to get and doesn't have great results when used on farm.

But we're gonna talk a little bit more about parasitoids because they are much more common and much easier to get.

So, these guys are really interesting little critters.

They're actually wasps, they're stingless wasps, they're very tiny, like the size of an ant, and you can purchase them from multiple suppliers across the country and they'll be delivered to you in little plastic bags, like you can see in the bottom right here, filled with shavings and what looks like fly pupae or rat droppings if you haven't seen fly pupae.

So, it looks like you're being sent this bag of things you don't wanna put in the environment.

But basically what you're getting are fly pupae that have been stung by a female wasp.

And if you look at our figure to the left, that female wasp is on the pupae in the middle.

And what happens is she lays an egg in a live developing fly, that egg hatches into a larvae that then eats the adult fly or sorry, eats the developing fly.

Then, the parasitoid emerges, killing the fly, and she goes off to find a new host.

So, it's a very effective way to have these little critters work for you.

But you have to apply them in ways that protects them from harm because they are still really small and a little bit different than what the manufacturers generally tell you to do.

So, you can apply them by a scatter method so you just scatter them on the ground, you can put them in these little dixie cups and kind of place them near posts in the barn or by the manure piles, or you can hang them in like a cheesecloth or mesh bag in different places.

But you wanna make sure when you apply them you're keeping them safe from hooves, from people stepping on them, from chickens if you have them.

So, you wanna try and keep them somewhat protected while you're waiting for the wasps to emerge.

And the other thing is you want to make sure that you're applying them every two weeks, not every month, they're usually sold so you get a delivery every month, but that fly lifecycle is every seven days.

The parasitoids take at least three to four weeks to develop so there's no way that you can keep up with your fly population with deliveries every month so you wanna try and have them here every two weeks or so.

You can have fewer released every two weeks, that's better than having more released every month.

And we have some really good resources on using parasitoids on horse farms.

Okay, chemical control, this is the top of our pyramid.

This is using natural or synthetic pesticides, so I an saying natural, not just synthetic, this does include our natural products as well.

And we're gonna spend a little bit of time on this because this is kind of the go-to for most of us when we see a fly issue.

And there are three common types of or groups of chemical control methods.

So, topical repellents, residual and facility sprays, so primarily misters, so in the barn misters and baits.

But there is a fourth one that isn't always thought of to fit into this category, and that's the use of feed through control for flies.

So, in this case with feed through, your horse eats it and the fly lifecycle is broken up at the larval level because the chemicals that are in that product do not allow the fly to develop any farther.

So, we're gonna talk about all four of these, but in order to really understand chemical control and kind of the do's and the don'ts of chemical control, we need to start with understanding resistance, so pesticide or insecticide resistance.

Most filth flies in the United States have extremely high resistance to most of the chemical compounds that we have available.

I'm gonna take a minute to talk about how that happens just so we're all on the same page.

So, basically if you're starting with a population of flies and you spray an active ingredient on those flies or they come in contact with a compound, and you have a fly in that population that may be slightly resistant or have some sort of mutation that doesn't kill them, but may kill some of the other flies, you can see the resistant fly here in orange and the other flies in the black.

The next generation of flies is going to have more of those resistant flies.

So, you see a couple more orange flies in there and maybe more black ones around.

And then if you spray it again and you kill off more of the black flies, you end up with even more in your population that are resistant.

So, over time, and it doesn't have to be that long because remember, flies have a pretty quick lifecycle, you are inducing resistance to that active ingredient by continuing to spray it without rotation.

So, we need to have a little bit of an understanding of not the product name that we're using, but the active ingredients in that product, which is always given on the label, in order to help combat resistance.

And unfortunately, this is what's happened to filth flies 'cause they're not just a problem in horse facilities, they're a huge problem in cattle and poultry facilities so you end up with a table that looks like this.

So, in the left-hand columns on both sides, these are the active ingredient classes so that the insecticide classes that are available to be used for fly resistance.

And on the far right column where you see all those blue names and dates, those are all the studies that have demonstrated resistance in flies to those compounds.

So, right now you can see the bottom, there's a group of insecticides called diamides, that is right now the only compound that we have available that does not have documented resistance in flies.

All the other ones do, including the baits, so the neonicotinoids and the carbamates are our common baits that we see on the shelves, so Golden Malrin and QuickStrike.

Pretty much all of our fly sprays and misters are the pyrethrins and pyrethroids, which are at the top of that second group with one of the longer paragraphs of resistance.

And then, all of our feed through products currently available are closer to the bottom, they have also had documented resistance.

So, as I mentioned, there's one kind of example of one group of chemicals that hasn't had resistance, and that is the diamides.

There is a bait called Zyrox Fly granular bait that uses that class of insecticides.

So, to date there hasn't been any documented resistance, but flies have a habit of developing resistance in about five years after the release of an active ingredient, usually because of misuse.

So, there are some dos and don'ts for chemical control to make sure that we keep that resistance as low as possible.

So, the first is rotating active ingredients, so this is not products so don't go buy a Farnam product and then go buy something from somewhere else or UltraShield versus Endure or whatever.

It's not the product name that matters, it's the active ingredient in the product.

So, if you're using baits, even the Zyrox bait and you wanna put that Zyrox bait out, that's great, put it out, the next month rotate it to a different bait, the next month rotate it to a different bait, or try at least to alternate baits over the period of the fly season.

You also wanna make sure you're reading the label and ensuring the product that you're buying lists the pest that you're trying to attack on that label.

So, you don't wanna be putting baits down if you're trying to control stable flies 'cause stable flies are not going to be attracted to baits.

And you don't wanna use chemical control as the sole method of control, right?

So, we said judicious use is good, but we don't wanna be relying on chemical control or using a product inconsistent with its labeling.

And this is what happens sometimes.

So, if you use a product inconsistent with its labeling, it can be downright dangerous for you or your animals.

So, often people will see like pyrethroids, for example, on the bottle of fly spray and say, "Well, if it's got 2.5% a half percent pyrethroids in it then 10% has got to be better," and they'll see a livestock pyrethroid on the shelf at Tractor Supply and they'll hook a spray bottle up to it and they'll spray it on their horses.

But horses are very sensitive to pyrethroids, and really most chemicals, and they can cause burns like you see here when sprayed at that high level.

So, you wanna be very careful that you read the label and make sure it's appropriate for horses, it's appropriate for your pest of interest, and that you know how to appropriately apply the product.

A couple quick notes on these next group, first facility sprays.

So, I highly discourage misters in all cases with no exception.

Misters apply very low doses of whatever active it is, and all it's doing is increasing the likelihood of resistance.

And I see people like, "Oh, I have these misters and flies just fall down and then get back up," and that's exactly what's happening 'cause you're not putting a high enough dose down to kill them, certainly not to repel them, and multiple generations become more and more tolerant of the product.

Even if it is an essential oil-based product or a natural product, you're not getting the effect that you're hoping for.

What you are getting is a whole bunch of aerosols in the environment that you are inhaling and your horse is inhaling.

And if it's a pyrethroid base that non-targets like cats who are very sensitive to pyrethroids are also inhaling, so I don't recommend them.

And feed throughs are another control method that I get a lot of questions about which can be very effective as part of an IPM plan.

They're relatively easy to use, easy to get, they only target flies so you're not gonna be impacting your good dung beetles out there in the pasture, but they have to be used correctly, so they have to be given to every horse on the premises.

So, just because your horse is treated doesn't mean that the other 25 horses on the property are not gonna be suitable for fly development, right?

And resistance has been documented to those active ingredients, but at a lower level.

So, it's much more common for resistance to be localized with feed throughs 'cause they're overused on a farm than it is to be widespread, so again, rotate the active ingredients.

And they will not target flies that don't develop in equine manure, so your face flies and your horn flies are not gonna be affected by this.

Baits, so again baits are really easy to use.

There are some concerns that you can get some non-targets eating them.

They are poison, so if you place them improperly, you may get kids coming into contact with them or chickens coming into contact with them.

And that they are housefly specific, so again, any of your other three species are not gonna be affected by baits.

There are, as I mentioned, one, there is one product on the market that has no documented resistance and that's the Zyrox bait.

But again I do recommend that you rotate bait products so you prevent buildup of more resistance.

To put baits out, you can hang them kind of like in this milk jug.

You drill some holes in the milk jug and you put them at the bottom and you hang them up where you see flies and flies die in the milk jug.

Or you can use something like a plate, but absolutely do not scatter baits in the environment 'cause it increases the likelihood of contact with non-targets.

And then, finally repellents.

Repellents are really interesting, they're kind of everybody's go-to, they were mine as well when we got a fly problem and they can help with short-term relief, especially from biting flies.

And they're the only method we really have for full body coverage when we're out riding, like if you're on a trail ride or something.

But there are some buts, some cons or some caveats that they need to be applied correctly.

Most are ineffective so you have to be careful which ones you select, and they do degrade in the environment or they have a loss of effectiveness when the horse sweats or when they roll so we have to be careful about those.

So, one of the questions I got the most and people thought I knew the answer for some reason right from the get go about which fly repellent actually works.

And I actually didn't, I didn't know the answer to which one works knowing what I did about flies.

And so, I actually worked with a student here at Penn State, one of the first things I did when I got here to evaluate which repellent should I tell people to go to or are there any?

And this is a really, really busy figure so I'm gonna try and break it down a little bit.

But basically we looked at three different, what you would consider natural repellents and four synthetics, so four pyrethroids.

Our natural ones were Ecovet, Equiderma, and Outsmart, and our synthetics were Bronco, Endure, Optiforce, and Ultrashield Red.

And the red lines across the screen are the 75%.

So, anything above that was 75% effective or 75% of flies remained repelled.

Anything below that I would consider bad, so they were not repelled.

And basically, it kind of surprised me to be honest, I didn't expect these results.

But what you can see, if we look at our synthetics, Bronco and Optiforce and Ultrashield Red at the bottom, that there wasn't a single product that lasted the 24 hours, certainly not 48 hours.

And only one of them, Ultrashield Red, lasted for about four hours, after that it tanked.

So, when we applied these, now granted it was in the laboratory, we didn't have sun so it may have been even worse than this unfortunately.

But when we applied these, we really didn't get much repelling effect from most of these in our fly population.

And this was a fly population that was from Pennsylvania.

So, that was disappointing, but when we looked at the natural products, there were two of them, Ecovet and Outsmart, that gave us a little bit of a fight.

So, I guess the other thing I should mention, there are three lines on each one of these figures, that's because we use three different concentrations, but I only want you to look at the top line in all of these because that was like straight out of the bottle 100% what you would be putting on your horse, okay?

So, Outsmart and Ecovet both lasted about 24 hours.

Outsmart was a a little less than 75% effective at 24 hours.

But Ecovet was the only one that out of the bottle lasted a full 48 hours, a full two days when we applied it.

I do not work for Ecovet, I have no association with that, I chose that particular one because it was a new product at the time and I've been hearing a lot about it, has a different mode of action than all of the rest of them because it confuses flies instead of really repelling them, they can't orient themselves, and that was the most effective one that I saw.

So, if I get asked questions, "Which repellent do I use?" That's what I say, is Ecovet, I can use less of it and I have more effect than I have found with any of the other products.

But repellents can only work as well as they're applied, so a little tutorial on the best method of application for any repellent that you choose.

The first is that even though they come in bottles with sprayers, what you do often is you go, "Spritz, spritz, spritz," and then you turn your horse out.

But they really need full coverage on the body to be effective.

And when you spray, you're creating these little aerosol droplets that hang out on the edges of the hair and then get burnt away.

You really want good contact over the whole body.

So, I use a mit, but you can use a rag or a brush, spray that whatever you choose and then wipe your horse head to tail down the legs to make sure you're getting really good contact on the body.

And then, consider using targeted application like with rollers or creams when you are dealing with things around wounds or some sensitive areas.

And then a final warning about essential oils.

So, I'm not talking commercialized oil blends, these are generally standardized, but plants tend to grow very differently and have very different chemical compositions based on where they've grown and what nutrients they had available to them.

So, when you have a commercial laboratory, they tend to have very standardized plant products they work with.

But when you don't have that and you're buying products off like Etsy or something like that, you really don't know if the product you bought, you know, June 1st is the same as July 1st, you have no standardized way to tell that those are gonna have the same level of success in terms of repelling flies.

So, I always ask folks to make sure that they're using products that have been evaluated for effectiveness when they're trying to prevent any pest.

And it's more important with things like ticks, which can actually transmit pathogens causing disease than it is flies, but I always recommend that you use a product that has been validated to work for that species and not try and mix them yourself.

Not only could they not work, but you could also create something that may be dangerous, as we saw with the burnt skin, unknowingly trying to help.

So, just be careful, word of caution, just be careful with the essential oil blends.

Okay, that was a lot of information, so thank everybody.

Thank you, everybody.

I'm excited to have given you a bunch of information.

I'm always willing to chat if you have any follow-up questions, anything site specific because a lot of this is very personal and what husbandry practices you have may impact what you're doing, so please feel free to reach out at any time.

And I believe, Danielle, there may be something coming around with other resources 'cause I sent something related to this.

- Yes, yes. - Okay.

We'll send, yes, there will be.

- [Erika] Awesome.

(Danielle laughing)

- So, thank you, that was a great talk, and we have a number of questions, we have about five minutes, we can get through some of them.

- Sure. - While we're going through questions, if you do have additional ones, again use the Q&A icon to add them in.

Again, I can't promise we'll get to all of them with the time, but you could certainly email Dr. Machtinger as well if you have a question.

And in the meantime, if you could also take a minute, I see Bethany has just put into the chat the evaluation.

Again, it just takes you a couple minutes, it's five questions to tell us what you thought of today and any future topics you'd like to hear from us in future programs.

All right, so let's do a couple questions real quick here.

So, do horn and face flies develop in goat manure and cattle manure?

- So, cattle manure, yes.

Primarily, well exclusively cattle manure.

Goat manure, interestingly also deer manure, which I found out this year, but they can support fly development, but it's usually when it's gotten wet and flat, the little pellets, they're not, it's not really conducive to flies, so it's kind of a secondary development habitat.

It doesn't mean it can't, but it's usually like if your manure is mixed in with hay and stuff, that's better than just the straight manure.

- All right, we have a couple long questions here, so gimme a second.

So, you mentioned having tried parasitoid wasps for fly control in stables, can you tell us how many wasps you introduce?

How many per horse, for example?

They've tried this in sheet folds in Quebec and the results weren't very interesting.

- Yeah, so first I always recommend parasitoids in conjunction with other methods.

So, they're not gonna be something that's gonna take care of all your fly problems, it's you have to use all those other sanitation and cultural control as well.

There really isn't a good number per horse, it's more related to acreage and if you've got like manure piles versus stables versus if you just have pasture horses, something like that.

So, the best thing I can recommend is to work with the supplier and ask them what they have because different parasitoid species work differently, and what they would recommend.

The numbers can fluctuate.

The more important thing is that you're putting them out more consistently than they typically recommend.

- Let's see.

So, are there feed through chemical controls available for cattle?

Could you use different feed through methods for horses and cows stabled together?

- Yeah, there are, and it uses the same chemical.

The point is just the chemical prevents a process from happening in the fly development.

So, even if they're on different chemicals, you can, although I believe, I believe cattle have the same, they use the same chemical so you could have cattle and horses on different products with the same active ingredient and then if you're rotating it, do a different product with the different active ingredient for that month.

So, but you can do that the same way.

There was another, was there another part in there?

I can't remember. - It was just for cow.

You know, it sounded like they might have cows and horses together. - And horses.

- So, looking for feed through options to do both of them.

- Yes, and interestingly, cattle also have, I believe like salt lick type things that can be used as well where horses don't.

- Let's see, your research on fly sprays is super interesting.

I noticed that's specific to house flies, is there any similar research looking at the effectiveness of different fly sprays on stable flies?

- No, there hasn't.

Stable flies have less of a resistance because they're not typically problems in poultry primarily, which is where we get a lot of resistance.

And we chose house flies because they have the highest levels of resistance.

So, this isn't a great...

Extrapolating isn't great because biology can be very different.

But if it's working on house flies, I'm more likely to think that it could work on other flies than if we had done it on stable and tried to work to house fly.

So, it's likely there's some level of a kind of reciprocity there I guess, if you will, with stable flies, but we haven't specifically looked at them.

- We'll do one more question, so do you have any experience with feed additives like brewer's yeast?

- I don't with brewer's yeast.

We have worked with and investigated garlic, that's the one I get a lot.

There's no indication that garlic works to repel flies or reduce fly numbers.

And there's some veterinary concerns with garlic, which can cause anemia on horses as well.

So, we always say make sure you're working with your vet whenever you're trying to give your horse something so they are aware.

- All right, so we didn't get to quite all the questions, but again you can, I don't know, Erika, if you, I mean, we're at one o'clock here.

- [Erika] Yeah.

- So, again, if you have questions, you can certainly contact us.

We are going to email out the recording of this webinar and some of the supplemental sources that Dr. Machtinger put together for all of you.

Again, if you didn't fill out the evaluation, we'd appreciate you taking just two minutes of your time to do so.

And thank you all for joining us, and thank you, Dr. Machtinger, for your wonderful talk.

- Of course.

- All right, have a good day, everyone.

Thanks for joining us.