Core Topic Briefs: Using Insect Pheromone Traps
Well hi, my name is John Tooker I am an extension entomologist with Penn State and today I am going to talk to you about pheromone trapping.
We are standing in front of a corn field here.
A lot of caterpillars that are pests of corn can be easily controlled with BT technology.
that is Transgenic corn that is an insecticidal to those insect species but many aren't and Black Cutworm is a great example of that.
Black Cutworm is not easily controlled with BT corn, is not easily controlled with seed treatments so one way to get a handle on your local population of Black Cutworm and understand if it is posing a threat to your field is to use a pheromone trap which is just what I have here.
This pheromone trap would be set with the pheromone of the female moth and that smell of the female moth would attract the male moth, we would capture the male moths in the trap just by opening it up and looking at it and counting the number of moths and based in the number of moths we find, we can asses whether this field or adjacent fields or even regional fields are at threat from Black Cutworm damage.
So when you are looking for Black Cutworm is good to know what the moths look like, most of the moths you are going to catch in a Black Cutworm trap are Black Cutworms, very specifically responding to the pheromone that the female has produced.
I happen to have some Black Cutworms here with me today, typical entomologist box of insects and here is the moth and they are very distinctive in that they have this distinct black dagger like markings on the wing so if you find a moth in your trap often times they look faded, a little bit beat up because they sat in the trap, maybe the trap is rattling around in the wind or there is a little bit of water in there but these little black daggers are very distinctive and allow you to identify this specifically as a Black Cutworm so when you see this moths all you have to do is count them, then you can share this information with someone like myself who is coordinating a regional effort to trap for Black Cutworm and share that with a larger audience and tell people across the state what portions of the state are at risk from Black Cutworm that year.
So there are kind of two reasons you can use a pheromone trap for moths, one is to try to asses the population locally to see what the risk is to a particular field or a particular area from a moth pest species, another reason is just to generally understand a population.
So if you want to trap for Black Cutworm or other moths that can be trapped with pheromone traps you can buy a trap like this.
I bought this from a company called Great Lakes IPM® but they are widely available through Gempler's® or other locations and it comes in pieces.
It has the base here, has the cap here and there is a lid that keeps rain out of it.
We put the pheromone in this little cage.
The cage has a top to it, you pop that off, throw the pheromone inside, put that back together like this and you are ready to trap, all you have to do is hang this next to a field on a shepherd's hook or on some type of fence post, keep it about three feet of the ground, keep it away from a hedge row because we do not want it too close to a hedge row, we don't want to hang it from trees for example because we want that smell of the pheromone to disperse and to be able to attract the moths, if it is next to a hedge row, the smell of the pheromone can get tied up in the smell of the trees and you just want to avoid that.
The pheromone looks like a little eraser, I have one in my pocket.
Here is the pheromone, it looks like a little rubber eraser, the smell of the female moth is impregnated in this little eraser looking thing, we call it a septum and we just pop that septum into the trap and you are ready to go.
I should say you are almost ready to go because when a moth gets in here, it is not going to die, we want the moth to die in the trap so you can count it so we just add an insecticidal strip in the trap, usually hang that using a paper clip and you really are ready to go.
This strip is impregnated with a volatile insecticide that will kill the moths in the trap and then when you are ready just come and check the trap and see how many moths are inside.
I recommend that folks check their trap every 4 days or every week or so.
Certainly does not have to be everyday but the more the better so we can track the number of moths.
When we are looking for Black Cutworm when we find eight moths over the course of two nights, that is what we call a significant flight of moths and then we know that that field or even adjacent fields and again the region, are at a higher risk of damage from Black Cutworm.
Then what we can do is start accumulating degree days, degree days are just heat units based on the average temperature for every day.
When we reach 300 degree days, then I recommend growers to go out in their fields and look for Black Cutworm damage.
The best way to handle Black Cutworm damage, the most economical way is to do a rescue treatment of insecticides.
If you find a damaging population in your field, then you are applying insecticide if necessary and it is all based of the timing that we can establish from a pheromone trap like this.
In Pennsylvania we have a new pest species that attacks corn called Western Bean Cutworm, this is a pest that we first detected in Pennsylvania in 2009 and we are using pheromone traps to understand how wide spread this moth species is.
We have only found a single caterpillar so far so we are pretty sure it is not an economic pest in Pennsylvania.
We are trying to use the traps to understand where the moths are to figure out which parts of the state are more at risk.
So Western Bean Cutworm is not a typical cutworm in that it is not cutting of plants early inf the spring, it is a pest species of corn ear, so just about this sized corn and it will get, the individual caterpillars will get down in the ear and feed upon the kernels of the developing ear.
Off course this can be very damaging if the populations are high enough but thus far in Pennsilvania all we find is the moths using pheromone traps which look like this to understand which part of the state the populations are developing in and we can tell growers if they are at risk from damaging Western Bean Cutworm or not.
We can tell those growers if they should be scouting in their fields to look for their caterpillars based on the high or the low number of moths that they find in their traps so that is Western Bean Cutworm, a new pest in Pennsylvania.