Pest Identification

This tool was developed by Preservation staff for use at University of Illinois libraries. The table contains information about bugs that commonly appear on traps in this area, including common and scientific name, adult and often larval images, and notes relating to the bug.

NameScientific NameApprox. SizeMain ImageAlternate ImageLarvae/Nymph ImagePest CategoryNotes
AntFormicidae family2-15 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererThis family covers a wide variety of any sizes and colors, but all are non-threatening to collections.
Ant, FlyingFormicidae family2-15 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererFlying ants have elbowed antennae, two pairs of wings of different sizes, and long legs (to differentiate from termites)
Bee, Yellow JacketVespula or Dolichovespula12-16mmDanger to Humans
Beetle, AsianHarmonia axyridis5-6 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererThese beetles are unavoidable in the fall and early winter after soy crops are harvested.
Beetle, Cabinet (Warehouse)Trogoderma angustum2-4 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of "Mike Quinn, TexasEnto.net"

Courtesy of "Mike Quinn, TexasEnto.net"

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererThese beetles are unavoidable in the fall and early winter after soy crops are harvested.
Beetle, CarpetAnthrenus verbasci2-3 mm
Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Library/Museum PestBacks covered in colored scales. Larvae are particularly destructive and eat animal specimens, fur and feather, and woolen textiles.
Beetle, CigaretteLasioderma serricorne2-3 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of Clare McLellan Museum Victoria

Courtesy of Clare McLellan Museum Victoria

Courtesy of Entomology Dept

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestAlso called a tobacco beetle. Similar in appearance to a drugstore beetle, but has finer, more straight antennae and no lines on the back of their wing covers. Eat a wide range of dried plant materials including tobacco, but also known to eat animal proteins.
Beetle, ClickConoderus bellus2-6 mmCourtesy of the Department of Entomology, University of Illinois at Urbana-Champaign Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign[/caption]
Courtesy of the University of Illinois at Urbana-Champaign Library

Courtesy of the University of Illinois at Urbana-Champaign Library

BlundererIdentifiable by the pointed protrusions on the corners of the thorax where it meets the abdomen. The larva are also called wireworms.
Beetle, DrugstoreStegobium paniceum2-3 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of Clare McLellan Museum Victoria

Courtesy of Clare McLellan Museum Victoria

Courtesy of Simon Hinkley & Ken Walker Museum Victoria

Courtesy of Simon Hinkley & Ken Walker Museum Victoria

Library/Museum PestAlso called a biscuit beetle. Eat dried vegetable materials and cellulose, including tobacco, nuts, and dried plant specimens. Also noted to eat paper mache, some animal specimens and fungi.
Beetle, FurnitureAnobium punctatum3-5 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of Clare McLellan Museum Victoria

Courtesy of Clare McLellan Museum Victoria

Courtesy of Clare McLellan Museum Victoria

Courtesy of Clare McLellan Museum Victoria

Library/Museum PestWood borer, leaves gritty frass and bored exit holes about 1.5-2 mm in diameter. Prefer cool, damp conditions.
Beetle, GroundCarabidae family6-38 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestWood borer, leaves gritty frass and bored exit holes about 1.5-2 mm in diameter. Prefer cool, damp conditions.
Beetle, HideDermestes peruvianus7-10 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of Clare McLellan Museum Victoria

Courtesy of Clare McLellan Museum Victoria

Library/Museum PestEat leather and skins, but not generally good condition tanned leather. An infestation may indicate a dead rat/pigeon or other animal somewhere on the premises.
Beetle, OddThylodrias contractus1-4 mm
Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Library/Museum PestOnly the males have wings. Eats dead insects and known to attack natural history specimens.
Beetle,

Powderpost
Lyctus brunneus5-6 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of Ken Walker Museum Victoria

Courtesy of Ken Walker Museum Victoria

Library/Museum PestWood borer, leaves very fine talc-like frass. Tends to eat relatively fresh wood.
Beetle, RoveStaphylinidae family1-20 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererIdentifiable by short elytra (wing covers that typically hide the abdomen) and segmented abdomen.
Beetle, SpiderPtinus tectus3-5 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestFeed on animal and vegetable detritus, can damage books, paper, textiles and wood if located near food. Frequently a sign of poor housekeeping or animal carcasses or nests in the vicinity.
Beetle, WeevilCurculionidae family3-10 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererMost have a well-developed downward-curved snout; antennae elbowed, clubbed, and the first segment often fits into a groove in the side of the snout.
Book LousePsocoptera1 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of Ken Walker Museum Victoria

Courtesy of Ken Walker Museum Victoria

IndicatorFeed on microscopic molds and can infest flour, paper and cardboard. Prefer warm, humid (above 60 % RH) environments.
Centipede, HouseScutigera coleoptrata5-30 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

IndicatorThe house centipede, has an average of 17 pairs of very long, delicate legs and a rigid body. The legs also have dark stripes. House centipedes feed on spiders, bedbugs, termites, cockroaches, silverfish and other household pests.
Cockroach,

American
Periplaneta americana30-40 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestCockroaches are ubiquitous in campus environments and travel through steam tunnels under campus and into facilities closets. Cockroaches can damage library materials by chewing on them or excreting onto them, which causes staining. American cockroaches are the largest species found indoors in IL and are all brown with large wings.
Cockroach,

German
Blattella germanica 10-15 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestSmaller than the American Cockroach. Identifiable from other cockroaches by the two black stripes on the back of the thorax.
Cockroach, Oriental
Blatta orientalis30 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestSmaller than American Cockroaches. Identifiable from other cockroaches by the lack of wings and darker color.
Cricket, Ground .Trigonidiidae Nemobiinae 5-12 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererCrickets often "swarm" in the late summer and may enter buildings in large numbers, but pose no threat
Damsel Bug Dicyphus hesperus 4-8 mm
Courtesy of Entomology Dept

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the University of Illinois at Urbana-Champaign Library

Courtesy of the University of Illinois at Urbana-Champaign Library

Blunderer
Fly, FruitDrosophilidae family 3-4 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of Sarah McCaffrey Museum Victoria

Courtesy of Sarah McCaffrey Museum Victoria

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererThese are often a sign of poor housekeeping and unclean trashcans or rotting vegetable matter.
Fly, variable Muscidae family 3-8 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Blunderer
Gnat Anisopodidae family 3-6 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Blunderer
Leaf Hopper Cicadellidae family 3-6 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Blunderer
Millipede Diplopoda class 20-50 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererMillipedes are commonly found during the Spring and Fall as they enter buildings from the outside. They can live in many different habitats such as mulched flower beds where moisture, humidity, and organic matter are high.
Minute

Pirate Bug
Anthocoridae family 2-4 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the University of Illinois at Urbana-Champaign Library

Courtesy of the University of Illinois at Urbana-Champaign Library

BlundererMinute Pirate Bugs are most easily recognizable by the V shape their elytra (wing covers) make above the wings.
Mite, Predatory Several 1 mm
Courtesy of the University of Illinois at Urbana-Champaign Library

Courtesy of the University of Illinois at Urbana-Champaign Library

Courtesy of the University of Illinois at Urbana-Champaign Library

Courtesy of the University of Illinois at Urbana-Champaign Library

IndicatorPredatory mites feed on other pests. Frequently, they are orange or red in color
Mite, variableSeveral1mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

IndicatorMites are an indicator of high-humidity environments. Most are non-biting, but some varieties can bite humans.
Mosquito Culicidae family 3-10 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererA nuisance that frequently follows staff and patrons into buildings in the summer months.
Moth, Clothes Tineola bisselliella 10-20 mm
Image source: museumpests.net

Image source: museumpests.net

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestLarva found in dark storage areas on fur, feathers, skins, wool and soiled textiles.
Moth, variable Lepidoptera order 5-20mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererExcept for clothes moths, most common outdoor moths are blunderers into libraries
Noseeum

(biting midge)
Several 1-2 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the University of Illinois at Urbana-Champaign Library

Courtesy of the University of Illinois at Urbana-Champaign Library

BlundererThis often come into buildings on people who have traveled through the grass recently.
Pill Bug /

Sow Bug
Armadillidiidae family 8-12 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

BlundererPillbugs can roll up into a tight ball when disturbed. Although they sometimes enter in large numbers, they do not bite, infest food, clothing, or wood. Since they require moisture, they do not survive indoors for more than a few days unless they are in very moist conditions.
Silverfish Lepisma saccharina 5-15 mm
Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Image source: museumpests.net

Library/Museum PestAssociated with high RH (over 75%). Feed on microscopic mold, glue, ink, and starch. Grazers
Spider Araneae order 5-40 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

IndicatorEats other insects. See identification guide for Brown Recluse spiders. Otherwise, usually harmless
Spider, Black WidowLatrodectus mactans3 -10 mm Danger to Humans
Spider, Brown RecluseLoxosceles reclusa7-12 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Danger to Humans
Springtail Entomobryidae family 1 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Image source: museumpests.net

Image source: museumpests.net

IndicatorSpringtails are carrion feeders that prefer high humidity. Very small and easily missed, they are best identified by their distinctive shape.
Termite
Kalotermitidae

or

Rhinotermitidae
4-7 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Library/Museum PestWinged and wingless (worker) termites have straight antennae and a long body with short lets. Winged termites have two pairs of wings of the same size and shape. Can infect timber and wooden objects as well as wooden structures. Dry wood termites can infest wooden objects.
Wasp, variable Vespidae family 12-16 mm
Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Courtesy of the Department of Entomology, University of Illinois at Urbana-Champaign

Danger to HumansHowever can form hives inside buildings. If large population is observed, call about extermination and/or removal of nest.

Additional Pest Identification Resources

Borror, D., & White, R. (1970). A field guide to the insects of America north of Mexico. Houghton Mifflin Company.

Identification, Images, & Information for Insects, Spiders & their Kin for the United States & Canada. Integrated Pest Management. (n.d.). BugGuide. https://bugguide.net/ 

Milne, L., Milne, M., & Rayfield, S. (1998). National Audubon Society field guide to North American insects and spiders . A.A. Knopf. https://i-share-uiu.primo.exlibrisgroup.com/permalink/01CARLI_UIU/gpjosq/alma99405613012205899

Museum Pests Working Group. (n.d.). Identification Image Library. Museum Pests. https://museumpests.net/

Northeast Document Conservation Center. (2015). 3.10 Emergency Salvage of Moldy Books and Paper. Preservation Leafletshttps://www.nedcc.org/free-resources/preservation-leaflets/3.-emergency-management/3.10-integrated-pest-management