Seeing Double? Insect and Plant Look-Alikes
Seeing Double? In the world of Pests and Pesticides, identifying a pest can often become confusing. Something that looks like it should be a bad bug or plant could really be a good bug or plant!
This is a digital supplement to the Penn State Extension Pesticide Education Program 2021 Ag Progress Days Display.
Cranefly
Craneflies are commonly mistaken for giant mosquitoes. They look similar; both belong to the same order and suborder, but are in different families; and both have characteristically long, slender bodies, legs, and wings. However, they can be distinguished easily by characteristics of the head, thorax, and wings. Crane flies have a relatively long head, vaguely similar in shape to a horse's head; at the tip of the "snout," they have small sensory organs called palps, but the mouthparts are vestigial (tiny, underdeveloped, and nonfunctional). Crane flies also have a distinctive V-shaped groove on top of the thorax and their wings are bare, with no scales. Crane flies also tend to be much larger than mosquitoes. Adult crane flies do not feed and primarily exist to mate and find appropriate places to lay their eggs. Depending on the species, crane flies lay their eggs in damp soil, rotting wood, or leaf litter, or in/near streams or ponds. The larvae of most crane flies feed on any sort of decaying organic matter they can find, though a few soil-dwelling species feed on grass roots and may damage turf, while some of the aquatic species are predatory on small, soft-bodied invertebrates. The larvae are distinctive; they look like big, leathery maggots, typically with several fleshy tentacles surrounding the breathing holes at the tip of the abdomen; the head is greatly reduced and sunken into the thorax, which can make it difficult to determine which end is the front and which end is the back.
A common nickname for crane flies is "mosquito-hawk," based on a misconception that crane flies hunt and eat mosquitoes. In reality, adult craneflies do not feed, or at most may sip dew or nectar, so they do not hunt mosquitoes. However, their role as decomposers and prey for other wildlife makes them important members of a healthy insect community. In most cases, their interactions with people are limited to resting on building walls, especially around lights, and being relatively large and conspicuous.
Double Agent: Mosquito
There are approximately 3000 species of mosquitoes worldwide, with ~200 species in the United States and 60 species in Pennsylvania. They lay their eggs on or near still water, and the larvae and pupae develop in the water. Mosquito larvae breathe air, so most require access to the water's surface or they will drown. Different types of mosquitoes favor different types of aquatic environments for their larvae. Container-breeding mosquitoes only need about one fluid ounce of water to have enough space to breed. These containers may be natural, like puddles on rocks in streams or tree hollows, or may be artificial, like bird baths, clogged rain spouts, or pieces of trash. Flight seasons and behavior of adult mosquitoes vary by species; most are active at dawn and dusk and stay moderately close (within a few hundred yards) of their breeding site, but some are active during the day or through the middle of the night, and the strongest fliers may venture several miles from their breeding source. Because mosquitoes tend to be slow, weak fliers, they usually take shelter in windy or rainy conditions, and may be repelled from small outdoor areas with electric fans. Adult mosquitoes spend most of their time resting in cool, humid, dark areas that are protected from wind; these areas may include storm sewers, dense bushes or shrubs, or spaces under porches and decks.
Very few, if any, species in Pennsylvania depend upon mosquitoes as a food source; while many generalist insect predators, including bats, birds, spiders, dragonflies, damselflies, diving beetles, and fish will eat mosquitoes occasionally, mosquitoes rarely make up a significant part of their diets. These predators also typically fail to consume enough mosquitoes to make noticeable changes in mosquito populations for people. However, adult mosquitoes do feed on nectar, and their importance as pollinators is not well understood; therefore, they may be important as pollinators for some plant species. Female mosquitoes of many (but not all) mosquitoes bite vertebrates to suck blood; they use the protein from the blood meal to produce eggs. Of the blood-feeding species, some require a blood meal to produce eggs, while others can produce eggs with or without a blood meal, but produce more eggs if they get a blood meal. Not all of the blood-feeding species bite people; some are specialized to feed from birds, reptiles, amphibians, or other species of mammals. Only a small portion of Pennsylvania's mosquito species are actually pests that bite people and/or spread disease.
The human-biting mosquitoes cause two general types of damage: they are annoying, and they can harm people, pets, and livestock by spreading disease. The disease-spreading damage includes both the immediate harm of getting sick and the broader societal harm of burdening the healthcare system, lost work and productivity, costs of preventive medicine, etc. Diseases spread by mosquitoes globally include malaria, yellow fever, Dengue fever, Chikungunya, Zika virus, several forms of encephalitis (including West Nile virus), filarial worms, and dog heartworm. In Pennsylvania, West Nile virus and dog heartworm are the greatest concerns, though West Nile virus produces no or mild symptoms in the vast majority of cases, and dog heartworm is easily prevented and affects only dogs. Therefore, mosquito-borne disease is not a high risk in Pennsylvania, and nuisance biting is the greater form of harm they cause.
Mosquito management can encompass up to three "levels": personal, professional, and community. Personal mosquito management can be done by anyone; it includes looking for and eliminating mosquito breeding habitats or adult resting areas, limiting activities in areas prone to mosquito pressure when mosquitoes are active, wearing clothing that protects against mosquito bites (e.g., loose-fitting long-sleeved shirts and long pants), and applying mosquito repellent to skin that cannot be protected by clothing. Professional mosquito management is performed by pest control companies or specialized mosquito control companies on individual properties. This level of mosquito management typically includes surveillance for and elimination of mosquito breeding sites and resting areas, application of mosquito larvicides (pesticides designed to kill mosquito larvae) to breeding sites that cannot be eliminated, and barrier treatments (application of pesticides to trees and shrubbery to kill adult mosquitoes that rest there). Depending on the company, professional mosquito management may also use relatively new technologies like oviposition traps, autocidal gravid traps, and baits. The National Pest Management Association has recently unveiled a Quality Pro - Public Health certification for pest management companies working in mosquito management; the standards in the certification program were developed in collaboration with the U.S. Centers for Disease Control (CDC) and the American Mosquito Control Association and are quite rigorous, so this certification may be used to distinguish the companies most committed to quality mosquito management service. Community mosquito management is performed by specialized vector control districts and focuses heavily on rigorous surveillance and monitoring of mosquito populations, including setting traps for adults, sampling larvae from water bodies, and possibly using "sentinel chickens" to monitor for mosquito-borne diseases. Community mosquito management also includes education about local mosquito problems and recommendations for managing mosquito problems. When surveillance indicates that mosquito populations are becoming too high, the vector control district's treatment options primarily include source reduction (eliminating breeding sites or treating them with larvicides) or performing ultra-low volume (ULV) fogging. ULV fogging kills only adult mosquitoes (albeit very effectively), and unlike barrier treatments that can remain effective for 3-4 weeks, it typically remains effective only for as long as the fog remains in the air.
Assassin Bug
Assassin bugs are insects and considered "true bugs". These insects are mostly beneficial and are a good bug to have in your garden. They feed on other insects, including vegetable pests. Adult assassin bugs can be differentiated from similarly looking squash bugs by having a constriction or "neck" at the base of their head. On the other hand, squash bugs have a wide "neck". Assassin bugs also sometimes have a longer, pointier head than squash bugs. Like squash bugs, assassin bugs have piercing-sucking mouthparts. However, they use these mouthparts to pierce and inject enzymes into other prey insects to break down their inner parts so they can drink them. One of the assassin bugs commonly seen in gardens is the wheel bug, which has a distinctive cog-shaped wheel structure on the thorax. Assassin bugs can also bite humans, which can be very painful, so we recommend not touching or holding them directly.
Double Agent: Squash Bug
Squash bugs are insects that are part of the group called the "true bugs". They are notorious pests on cucurbit crops such as squash, zucchini, and pumpkins. Adult squash bugs will be found on and near cucurbit plants. They can be identified by their gray/white bodies and black legs and antennae, and by the outer edges of the abdomen that have alternating dark and light stripes. They will most likely be the only largely sized true bug with this appearance that you will find on your cucurbit plants. The immature, or nymph, squash bugs will start off brightly red-colored with a green abdomen, and will progressively become grayer or whiter, with the legs and head becoming gradually darker until they are black. They look like smaller, lighter-colored versions of adult squash bugs with no fully developed wings.
Adult squash bugs overwinter and emerge the next year in the middle of June. After emerging, they start feeding on cucurbit crops, mate, and lay eggs for a couple of weeks to up to a month. The eggs of squash bugs are laid in clusters of 4 to 40 eggs, are small and yellow to red-colored, and may be under or on top of leaves. The nymph squash bugs hatch after about 1 to 2 weeks and begin feeding on the cucurbit plants, becoming adults in 4 to 6 weeks. Squash bugs only have one generation per year. Squash bugs feed with straw-like piercing-sucking mouthparts and suck out plant sap by piercing the plant. Spots where squash bugs have fed first appear as yellow spots and then turn black over time. Small vines or plants can be decimated by squash bug damage.
If you grow cucurbits, squash bugs will probably show up at some point. To help minimize their damage to your plants and prevent them from dying, the first step is to make sure your plants are healthy. Make sure they are getting enough water and nutrients, because healthy plants are harder for the bugs to kill. After the cucurbits are done growing for the season, make sure to remove any plant debris. This will help remove potential overwintering sites for them. There are also several mechanical controls you can use to help control squash bugs. First is the manual removal and killing of squash bugs. You can crush them or place them into a container of soapy water to drown them. If you see any eggs, crush them thoroughly. Additionally, squash bugs like to hide under objects at night, so place some wooden boards or similar objects on the ground near or under squash plants. In the morning, check these boards and kill any bugs present. Control through these IPM strategies is easily feasible if there are only a few plants in the home garden. If you are still having issues controlling the pests, then there are some pesticides you can use to help control them. You can find these products in your local hardware or gardening store. However, also be aware that chemical control may not be very effective against adults, depending on the product used. Make sure to read the entire label and follow the directions. Any use of a pesticide that deviates from the label is a violation of federal law.
Hoverfly
Hover flies are sometimes known as flower flies. Adult hover flies are extremely acrobatic fliers and spend most of their time patrolling their airspace for mates or places to lay eggs or drinking nectar from flowers. Their nectar-feeding behavior makes them pollinators. Across the many species, the larvae live in a wide variety of environments, but the most common lifestyles of the larvae are either scavengers or aphid predators. The larvae of the scavengers typically live in wet environments or are fully aquatic, with aquatic larvae often having a long breathing tube off the tail that earns them the nickname "rat-tailed maggots." Rat-tailed maggots feed on any kind of rotting organic matter, and their long breathing tubes allow them to live in oxygen-deprived water; they are commonly found in sewage lagoons and manure pits. Aphid-eating hover fly larvae tend to be smaller, often have bright colors, and crawl all over plants hunting for aphids.
Adult hover flies usually have black and yellow stripes, which makes them look similar to bees, yellowjackets, and other wasps. The smaller species that produce aphid-eating larvae tend to be smaller, less fuzzy, and look more wasp-ish, while the larger species that produce rat-tailed maggots are usually plump and fuzzy as adults, which makes them resemble honeybees or bumble bees. Because they look similar to stinging insects, most would-be predators make no attempt at catching them. However, hover flies are completely incapable of stinging and are entirely harmless. Even the decomposing species generally do not carry and spread disease like house flies and many other decomposing flies do. Between decomposing waste materials, hunting aphids (which are garden and farm pests), and pollinating flowers, hover flies are generally considered to be beneficial. If hover flies are managed at all, they are usually managed to promote more hover flies rather than fewer.
Double Agent: Yellow Jacket
Yellowjackets are among the most familiar of wasps and are typically what people think of as a standard "wasp." However, their unique social behavior sets them apart as very unusual compared to most other wasps, which are solitary. Aside from ants, they are the most social wasps native to Pennsylvania. Hornets, some ants, and honeybees are introduced from Europe, and paper wasps and bumble bees produce smaller colonies.
A colony of yellowjackets follows an annual life cycle. In spring or early summer, mated queen yellowjackets that overwintered underground or in rotting logs emerge and begin building nests. They gather building materials - wood pulp - from dead or dying trees, fence posts, or any other unpainted wood source they can find. By chewing the wood pulp and mixing it with specialized saliva, the mixture dries into paper, which is what the nest is made of. After the queen has built enough of the nest to have a few brood cells, she lays her first eggs. She continues working on building the nest and hunts to feed her first batch of larvae. They need protein to grow, and she provides a hearty diet of chewed-up caterpillars, flies, maggots, and any other insects she can catch, possibly with some carrion (meat from dead, larger animals) mixed in. An adult yellowjacket cannot eat solid food, so the queen must make do on a diet of nectar and a protein-rich secretion that her larvae regurgitate for her. As soon as her first batch of offspring mature into workers, they take over nest-building and food-gathering responsibilities, and the queen focuses on laying more eggs. The colony grows quickly and may contain hundreds of workers by the time it is mature around mid-summer. The queen then produces the larvae that will produce the next year's queens and males. When these virgin queens and males mature, they leave the nest and mingle with queens and males from other colonies, ensuring genetic diversity for the next generation. The males die after mating, and the queens burrow underground or into rotting logs to hibernate until the following spring. By this point, the queen of the original colony is deteriorating from old age and stops laying eggs and producing the pheromones needed to keep the colony running smoothly. With no larvae to feed, the workers shift their focus to feeding themselves. The adults mainly eat sugars, so in late summer and fall, they primarily search for sweet, sugary, or alcoholic liquids to drink, which can make them a major nuisance at late-summer picnics and barbecues. With their society collapsing, their bodies deprived of protein, and drunk on sugar and alcohol from stolen beer and fermenting fruit juices, the workers become as aggressive as they will ever become in autumn, though they still rarely bother people who give them space. The colony completely dies when it freezes in winter, so the queens emerging the following spring must work from scratch to build fresh, new colonies and keep the cycle going.
Yellowjackets are important members of the insect ecosystem. Because the larvae are carnivorous, the adults diligently hunt other insects, many of which are pests. They are particularly known for taking caterpillars and maggots. The adults feed on sugary liquids; for much of the year, their primary food source is flower nectar, so they contribute to pollination. Both the hunting and the pollinating make yellowjackets particularly beneficial around gardens and farms. Their relatively large nests populated with intimidating, stinging workers effectively protect yellowjackets from most predators, though bears, skunks, and raccoons may still raid yellowjacket nests to feast on the fat- and protein-rich larvae.
Of course, yellowjackets are infamous for their stings, which they use to defend themselves and their colonies. Their vivid black-and-yellow striped body pattern advertises to any would-be predator that they pack a punch. However, yellowjackets tend to be very docile for most of the year, reserving their stings for direct threats to their nest. If you simply keep away from the nest, they will leave you alone. This pattern shifts somewhat in late summer and fall, when workers going through the mid-life crisis of no longer having a purpose raid parties and picnics; at this time, keeping food covered so they cannot access it is the best way to limit problems. Food trash should go into a covered trash container, or if that is not possible, trash should be kept far away from summer festivities so that the yellowjackets it attracts are safely well away from people. Placing yellowjacket traps away from sensitive areas may also offer some relief; they will catch and kill some of the yellowjackets and draw away more.
Unfortunately, yellowjackets have a knack for building their nests in very inconvenient places, such as under decks or porches, in exterior wall voids of houses, in landscaping plants, or underground in yards or along pathways. When a nest creates a sting hazard due to its placement, a pesticide application is usually the fastest, easiest, and safest way to eliminate the nest. Hiring a professional is recommended; hundreds of yellowjackets fighting for their lives are not to be underestimated, and any pesticide strong enough to stop those yellowjackets in their tracks is also potentially dangerous. However, if you must tackle a yellowjacket nest yourself, the following tips may help:
- Plan an escape route. If the yellowjackets get too defensive, a swift tactical retreat is the best way to keep stings to a minimum.
- Wear protective clothing. A bee suit is ideal, but any baggy, relatively thick clothing can keep the yellowjackets too far from your skin to deliver a sting.
- Wear respiratory protection; the smell of your breath can alert the yellowjackets that they're under attack. Even a dust mask, scarf, neck gaiter, or cloth COVID-19 mask can help.
- Bring soap and water. If you get stung, back away and promptly clean the sting site. The venom contains an alarm pheromone that will stimulate more yellowjackets to sting the sting site, and washing the sting site can limit or remove that pheromone and prevent subsequent stings.
- If possible, work at night when the yellowjackets are not active. If you need light to see what you're doing, place the light off to the side so any yellowjackets attracted to it fly away from you. Yellowjackets also cannot see red light, so a red light allows you to see but leaves them in the dark.
- Keep as much distance between yourself and the nest as possible. Also, watch the yellowjackets for a few minutes before treating to figure out their flight path(s), and stay out of their flight path.
- Watch the yellowjackets' body language, because they actually do give warnings before they sting. When they start flying in your face, circling you, or ramming into you, a sting is coming unless you back off.
- The papery envelope around a yellowjacket nest is made of many layers and is mildly water repellent. Dust-formulation insecticides applied into the nest entrance or injected through the outer envelope often work their way through the nest and kill all of the yellowjackets more efficiently than liquid insecticides do.
- Pole-mounted dusters can make yellowjacket treatments far safer by allowing you to treat a nest from 10-15 feet away.
- Do not expect an instant nest kill; do the treatment as well as you can, then check a day or two later to see if the colony is dead. It is safer to retreat the next day after the yellowjackets have calmed down than to try applying more insecticide into an already aggravated yellowjacket nest.
- Wasp sprays (e.g., Raid Wasp & Hornet Spray, Wasp Freeze, etc.) do not efficiently penetrate an entire yellowjacket nest, but can be used for self-defense while treating with other materials because they knock wasps out of the air almost instantly.
Pink Spotted Lady Beetle
Pink Spotted Lady Beetle InformationÂ
While many native lady beetle species have declined in recent decades, the pink-spotted lady beetle has remained common and may be the most common native lady beetle in Pennsylvania. Like most lady beetles, this omnivorous species is beneficial and typically eats aphids when they are available, but can live and reproduce on an all-pollen diet if it must. They do particularly well in corn fields, which often provide huge quantities of both aphids and pollen.
This lady beetle, like most, goes through complete metamorphosis, so their life cycle includes an egg, larva, pupa, and adult stage. The larvae are vaguely alligator-shaped and usually are predominantly black or dark gray with yellow, orange, red, or pink markings. The pupae stick to leaves, tree branches, or other surfaces by an adhesive organ at the tip of the tail, do not move beyond some slight wiggling if touched, and are usually orangish.
Double Agent: Asian Lady Beetle
Asian Lady Beetle InformationÂ
While lady beetles are usually beneficial, some may be pests at the same time. Some species, including the introduced Asian multicolored lady beetle, are known for forming large overwintering groups in the fall, and sometimes invade buildings in large numbers to hibernate. Many species of lady beetles will bite, especially if they are hungry or thirsty, which can make those home invaders that much more bothersome. They can also stink and stain walls if they are disturbed and release their chemical-laden blood as a defense. Also, the carcasses of the lady beetles that do not survive a winter indoors may attract pests like carpet beetles.
In the past, the U.S. Department of Agriculture has introduced several species of lady beetles into the U.S., including the Asian lady beetle, to help control some insect pests. However, as these introduced lady beetles have spread out and covered the same territories as many native lady beetles, several native species started to become rarer and sometimes impossible to find. The connection between the exotic lady beetles and the declining native species is unclear, but scientists suspect that the introduced species harmed the native species by competing with them for food, spreading diseases to them, and eating their eggs and larvae. Changing farming and pesticide application practices, land use change, and climate change may also contribute to the native species' declines. Unfortunately, the native species disappeared so quickly that scientists are left struggling to find beetles to study, so many questions about these declines remain unanswered.
Perhaps because it is extremely common, non-native, and exhibits several pestiferous behaviors, the Asian multicolored lady beetle has developed some myths and misconceptions. It is a type of lady beetle, not a "fake" ladybug or a lady beetle mimic. On farms and gardens, they do exactly what they were expected to do; they are excellent aphid predators, capable of eating huge amounts when aphids are abundant and coping with starvation better than many native lady beetles when aphids are in short supply. They have been known to bite but are not venomous, and while they are annoying, they are not a medical concern. Exaggerated stories circulating on the internet suggest that they can become embedded in the roofs of dogs' mouths, almost like parasites. In reality, lady beetles becoming lodged in dogs' mouths results from the dogs trying to eat the lady beetles and the beetles' dome-shaped shells acting like suction cups that hold them against the roof of the mouth. The lady beetles' defensive chemicals may then cause minor irritation to the dog's mouth. This can be prevented by keeping dogs from eating large numbers of lady beetles and by removing the beetles from the dog's mouth if a problem does develop. Overall, the Asian lady beetle can be a pest or a beneficial insect depending on your point of view.
Virginia Creeper
Virginia creeper is a fast-growing native perennial vine that is a member of the grape family and is often confused with poison ivy. It has a compound leaf made up of five green lance-shaped leaflets that are palmately arranged (shaped like a hand) on a long petiole (stem). The dark green leaflets have a serrated (tooth-like) margin (edges) and turn a brilliant scarlet or maroon-red in the fall. Virginia creeper forms dense spreading mats on the ground and climbs trees and other objects by means of tendrils (a threadlike stem) that have suction cup-like tips used for attaching to structures. Tendrils are produced from the main vine, and those that do not attach to a surface typically develop into a twisting "corkscrew" shape. The vine has a grayish brown bark that is rough due to leaf scars and becomes woodier with age. Clusters of dark blue berries are produced in late summer and remain on the vine into winter, which are eaten by a variety of song birds. Several species of moths and butterflies also use Virginia creeper to lay their eggs and serve as a food source for larvae. Native Americans used parts of the plant for medicinal purposes. Like poison ivy, there are a couple of old sayings for Virginia creeper - "leaves of five, stay alive" or " leaves of five, let it thrive."
Double Agent: Poison Ivy
Poison ivy is a native perennial plant that grows as a trailing vine. It forms mats and can cover fence posts and tree tops. In full sun, it can grow like a small shrub. The leaves are compound, meaning there are several leaflets attached to a common main stem, with three leaflets, two of which are opposite of each other. Leaflets are pointy, oval-shaped, with edges that can be smooth, toothed, or have one or more lobes. However, leaf shapes can be somewhat variable depending on the plant. The leaves are typically smooth and glossy, but can be slightly hairy and dull. In the spring and summer, the leaves are a bright or dark green color, turning to bright red, orange, or yellow in the fall. Dense clusters of green, hard, waxy seeds are produced in the summer, turning white in the fall, and will often persist through the winter. There are numerous species of birds that feed on the berries. The oil (urushiol) that causes the allergic skin reactions is produced by all parts of the poison ivy plant - leaves, stems, fruit, flowers, and pollen. Remember the old saying, "Leaves of three, let it be".
Staghorn Sumac
The Staghorn Sumac can grow up to 33 feet tall and is usually tree-like. It spreads by strong underground roots called rhizomes. Twigs are stout and densely red hairy. Leaves are alternate and pinnately compound, and 6 to 16 inches long. Each leaf has 11 to 31 coarsely toothed leaflets, green on top, and much paler underneath. Flowers are borne in clusters (panicles) of hundreds to thousands of flowers at the tips of branches. Flower clusters are up to 8 inches long and start with yellow to greenish small flowers. Fuzzy, bright red to brownish-red fruits develop after flowering. Staghorn sumac is an open land species often found on drier soils, but which may occasionally occur on low ground. It is a species of prairies and other grasslands, old fields, roadsides, savannas and woodlands, and fencerows. This species flowers in June to July, depending on the part of the country in which it is found. Bees, wasps, and beetles are strongly attracted to the flowers. Some bird and small mammal species eat the fruits. The fruits are sometimes soaked in water to make a tart, somewhat lemony drink. It is occasionally cultivated for its bright red to maroon fall color and persistent red fruits. Numerous lacey leaf cultivars exist. Without attention, it can become weedy.
Double Agent: Tree-of-Heaven
Tree-of-heaven, commonly referred to as ailanthus, is a rapidly growing deciduous tree native to both northeast and central China, as well as Taiwan. It was first introduced into the United States in the Philadelphia area in the late 1700s. Immigrants later introduced tree-of-heaven to the West Coast in the 1850s. The tree was initially valued as a unique, fast-growing ornamental shade tree with the ability to grow on a wide range of site conditions, tolerating poor soils and air quality. It was widely planted from New York City to Washington, D.C. By the early 1900s, the tree began losing popularity due to its "weedy" nature, prolific root sprouting, and foul odor. Tree-of-heaven has spread and become a common invasive plant in urban, agricultural, and forested areas. David Jackson, Penn State Extension Educator, created a video, Tree-of-Heaven: Native Lookalikes, to help explain the differences from black walnut and staghorn sumac.
