Pest, Disease and Weed Identification

Insect Identification and Control

To effectively control insect pests, you first have to be able to identify them. Use Penn State Extension’s resources and learn how to manage and control a variety of pests. Find information on leaf miners, spiders, mosquitos, mites, beetles, ticks, cockroaches, termites, wasps, hornets, slugs, earwigs, grubs, aphids, lanternflies, weevils, maggots, centipedes, and stinkbugs. Learn more about integrated pest management (IPM), and its practical application in the field, the backyard, or at home.

Insect Identification

The first step in adopting an integrated pest management system is proper pest identification, whether the pests are in the home, an equine facility, garden landscape, or an agricultural setting. Pests can also be a problem in high tunnels, red clover stands, and in soybean production. Help is available from experts such as Michael Skvarla, director of the Insect Identification Lab at Penn State’s College of Agricultural Sciences. Alternatively, you can learn to identify, prevent, and control the most common urban pests yourself.

Some of the most common insect pests include:

  • Wood-destroying pests: Hymenoptera, such as bees, ants, and wasps, and wood-infesting beetles, subterranean termites, and other termites can cause severe damage to structural timbers in buildings.
  • Mosquitoes: You can find more than 60 species of mosquitoes in Pennsylvania. The most widespread are the common house mosquito, white-dotted mosquito, rock pool mosquito, and the eastern tree-hole mosquito.
  • Cockroaches: We commonly find three types in the US. You can control the American, Oriental, and German cockroaches by eliminating what they need to survive, such as food, water, and shelter.
  • Spiders: You can find two dangerous spiders in Pennsylvania. Both the black widow spider and the brown recluse spider have a bite that may produce serious medical implications for humans.
  • Stinkbugs: Not known for causing harm to humans, a large number of them flying around in your home can be distressing and if you squash them, they’re very smelly.
  • Leaf miners: The larvae of these insects cause the damage. They mine their way through leaves and create blisters, hence the name. Vegetables most susceptible to this type of injury include beet, spinach, and chard.
  • Tree fruit insects: The biggest issue with insects such as yellow jackets and hornets is the number of farmworkers who get stung. The general public is also at risk in farm markets and U-Pick operations.
  • Spotted lanternfly: This is an invasive species that has spread throughout Southeastern Pennsylvania and nearby states.

Insect Pest Management and Control

Insect pests can cause substantial losses to crops and other types of plants. They can also cause human and animal diseases. For many years we have been dependent on pesticides as the only method of control, which has led to insect resistance and adverse effects of the environment, natural enemies, and human health. As a result, the ideal method for insect pest management and control is Integrated Pest Management.

Integrated Pest Management follows eight fundamental principles. These are:

  • Prevention and suppression
  • Monitoring
  • Decision-making
  • Non-chemical methods
  • Pesticide selection
  • Reduced pesticide use
  • Anti-resistance strategies
  • Evaluation

A key element for all these principles is identification. There are lots of resources available for both homeowners and commercial enterprises.

For homeowners and agriculture and green-industry professionals concerned about the spotted lanternfly, Penn State Extension has created multiple identification and management resources.

There are 900 species of ticks worldwide, 25 of which you can find in Pennsylvania. Penn State Extension provides an identification service and 90% of requests relate to two of these tick species.

East subterranean termites often cause damage to the structural timbers in buildings. Understanding their life cycle and the structural and chemical methods of control means you can reduce an infestation risk.

Integrated Pest Management can also be used to identify and control ants. The methods used are less hazardous to human health, less toxic to non-target organisms, easier and more cost-effective, plus are more likely to be effective in the long-term.

Mosquitoes are another common problem. They play a role in transmitting the West Nile virus, and one effective way to control them is to reduce potential mosquito breeding sites. Reducing the number of potential nesting sites is also a key element in spider management. For stinging insects such as paper wasps and yellow jackets, insecticides provide very effective control. If you’re using restricted-use, state-limited-use pesticides and regulated herbicides you will need a pesticide applicator license.

The monitoring of insect populations is one of the eight basic principles of IPM. You can monitor certain insects in the orchard using pheromone traps.

An increasing number of insect and mite pests have developed varying resistance levels to some of the insecticides commonly used. This has led fruit growers to adopt alternative approaches such as biological control by predators, pathogens, and parasitoids.

In this section, find plentiful resources on insect pest identification and management practices.

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  1. Apple Maggot in the Home Fruit Planting
    Articles
    Apple Maggot in the Home Fruit Planting
    By Grzegorz (Greg) Krawczyk, Ph.D.
    The apple maggot, Rhagoletis pomonella, is a serious apple pest that often damages homeowners' fruit. Tapping adults before they lay eggs can reduce the chance of injury.
  2. Nematode (Rhabditis sp.)
    Articles
    Nematodes in Commercial Mushroom Production
    By David Meigs Beyer, Ph.D.
    Parasitic and saprophytic species of nematodes associated with commercial mushroom growing are routine inhabitants of most agricultural soils.
  3. Photo: Jim Occi, BugPics, Bugwood.org blacklegged tick Ixodes scapularis
    Articles
    Ticked Off About Ticks
    By Sandy Feather
    In 2022, the Philadelphia Inquirer ran an article that stated Pennsylvania has the most cases of Lyme Disease in the United States.
  4. Two predatory ground beetles (Poecilus lucublandus) attacking a caterpillar.  Photo Credit: Nick Sloff
    Articles
    Predators Control Pests and Crop Damage In Transition to Organic
    By Mary Barbercheck, Ph.D.
    Predatory insects and spiders control insect pests and slugs, reduce crop damage in transition to organic crop production
  5. Ronald S. Kelley, Vermont Department of Forests, Parks and Recreation, Bugwood.org
    Articles
    Leaf Galls on Maple
    By Michael J. Skvarla
    Maple leaves are often infested with a variety of odd-shaped galls and blotches. Many of these are galls that are caused by mites and flies. They do not usually affect the health of the tree.
  6. Pennsylvania wood cockroach. Photograph by Brandon Woo via BugGuide, used with permission.
    Articles
    Wood Cockroaches
    By Michael J. Skvarla
    Wood cockroaches are beneficial decomposers found in natural habitats. They occasionally enter homes where they can be nuisance pests.
  7. Photograph by tgran via iNaturalist, used under a CC BY-NC 4.0 license.
    Articles
    Western Conifer Seed Bug
    By Michael J. Skvarla
    Western conifer seed bugs feed on conifer seeds and cones. They can be a nuisance to homeowners when they move indoors to overwinter in the fall.
  8. Spotted Lanternfly: What to Look For
    Articles
    Spotted Lanternfly: What to Look For
    Spotted Lanternfly, Lycorma delicatula, is a new threat to Pennsylvania and the United States, and experts are still learning how to combat it.
  9. Box tree moth adults. Photograph by Cosmi O. Manci, used with permission.
    Articles
    Box Tree Moth
    By Michael J. Skvarla
    Box tree moth is an invasive pest that has decimated wild and ornamental boxwoods in Europe, where it was introduced from Asia. In the fall of 2018, it was discovered in Toronto, Canada and may invade the United States.
  10. Micrathena gracilis female
    Articles
    Spined Micrathena
    By Steve Jacobs
    This small spider is commonly encountered in wooded locations, including landscaped residential and suburban locales.
  11. Yellowmargined leaf beetle (YMLB) adult. Photo: Michael Skvarla, Penn State
    Articles
    Yellowmargined Leaf Beetle Serious Pest in Pennsylvania
    By Michael J. Skvarla, Shelby Fleischer, Ph.D.
    Yellowmargined leaf beetle (YMLB) (Microtheca ochroloma) is a serious pest of cruciferous crops.
  12. Paraphidippus aurantius female. Photo by Isa Betancourt, BugGuide.net, photo# 1031635
    Articles
    Emerald Jumper
    By Steve Jacobs
    This colorful spider had not been recorded previously in Pennsylvania. However, it has been identified in Delaware, Maryland, Virginia, and ten other states.
  13. Joseph Berger, Bugwood.org
    Articles
    Hacklemesh Weaver Spiders
    By Steve Jacobs
    Amaurobius and Callobius species of spiders are found in damp locations under bark, leaf litter, and stones, as well as in woodpiles and other protected areas.
  14. Adult Eurasian red-and-black melyrid. Photograph by Tom Murray, used under a CC BY-ND-NC 1.0 license.
    Articles
    Eurasian Red-and-black Melyrid
    By Michael J. Skvarla
    The Eurasian red-and-black melyrid is a beetle that is occasionally found in homes. It is not a threat to human health or structures, so is a nuisance only because of its presence.
  15. Whitney Cranshaw,  Colorado State University. Bugwood.org
    Articles
    Banded Garden Spider
    By Steve Jacobs
    Banded garden spiders inhabit similar locations as yellow garden spiders, but are not as common in Pennsylvania.
  16. Pholcus phalangioides. Photo by Anita Gould, Flickr
    Articles
    Longbodied Cellar Spider
    By Steve Jacobs
    The longbodied cellar spider has extremely long legs and is found in many types of buildings throughout the year. It is not known to be in any way harmful.
  17. Parasteatoda tepidariorum female. Photo by Steven Jacobs, Penn State Extension
    Articles
    Common House Spider
    By Steve Jacobs
    Parasteatoda tepidariorum is widely distributed throughout the world. It commonly constructs webs in the corners of walls and windows in houses and barns.
  18. Cheiracanthium inclusum male. Photo by Steven Jacobs, Penn State Extension
    Articles
    Agrarian Sac Spider and Longlegged Sac Spider
    By Steve Jacobs
    Sac spiders are found on foliage; under leaf litter, stones, and boards; on buildings under windowsills and siding; and in wall and ceiling corners in homes.
  19. Rayanne Lehman, Pennsylvania Department of Agriculture, Bugwood.org
    Articles
    Clover Mites
    Clover mites are plant feeders that occasionally invade homes. These mites do not attack people, and they will not reproduce under indoor conditions.
  20. House Centipedes
    Articles
    House Centipedes
    House centipedes are of little concern to homeowners, despite their long legs and scary appearance. They feed on many different arthropods including pest insects.
  21. Jalysus wickhami. Photo © John Rosenfeld
    Articles
    Spined Stilt Bug
    By Michael J. Skvarla
    Spined stilt bugs are an occasional pest of greenhouse tomatoes that can cause flower and fruit abortion and unsightly feeding damage in mature fruits.
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