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Occasional Invaders

Below is a table describing occasional pests you may wind up seeing in or around your home at some point. The table will help you identify and learn about control methods for removing them from your property.

Species What size & color are they? How do you tell them from other insects? Where are they found in the house? What do they eat? How should you inspect? What can the homeowner do? What should the professional do?
BIRD MITES 1/64 inch.  So small you really can't see them Below that part of the house where a bird was nesting in the attic or under the eves. Bird Mites are parasitic in bird nests If you feel that you are being bitten by a "bug," look for birds' nests that have been abandoned.  You may see a group of mites leaving the nest and coming into your living area. Remove the abandoned nests.  Caulk & seal to prevent birds from nesting in the future.  Put up screen vents to keep birds out. Pesticides inside the house are not called for in this situation.
SPRINGTAIL 1/32-1/8 inch.  Usually white or gray, but may be black. Springtails hop about -- actually they spring, hence their name. Springtails are found only where it is damp. They need to have their bodies in contact with moisture. Springtails live outdoors where they eat decaying vegetation. Springtails often invade homes when the outside dries up.  They are searching for moisture. Springtails neither breed nor feed inside homes.  The homeowner should do nothing.  Springtails in the house will die.  The homeowner may try to control moisture, but in the middle of summer the house will always be more moist than the outdoors. Pesticides inside the house are not called for in this situation.  An outside barrier insecticide treatment during dry weather may prevent entry into the house.
SILVERFISH FIREBRATS 1/2 inch. Silver or brown in color Silverfish & Firebrats have 3 tails at the end of their body. In general, Silverfish & Firebrats prefer humid, warm areas -- 90 degrees or higher.  But there are some species of Silverfish that can withstand lack of humidity. Carbohydrates and protein:  rolled oats, dried beef, paper, linen, cotton, silk, rayon carpets, etc. If you see one Silverfish or Firebrat, check the parts of your house that are hot:  the furnace room, the utility room and around hot water heaters. One or two of these insects are usually not a problem -- every house will have some. If removing the occasional invader is not enough, call your professional. The professional will know where to look for sources of infestation.  The professional will know the proper pesticide to use in this situation.
CAMEL CRICKET CAVE CRICKET 1/2 - 1 1/4 inch.  Light to dark brown in color, often mottled with lighter or darker areas These crickets are wingless and humped-back.  They have extremely long jumping legs.  They can hop long distances and heights. In dark cave-like areas that are cool and moist.  Basements are preferred. Indoors, these crickets can feed on fabrics. Because these crickets prefer dark areas, they will be difficult to detect. One or two of these insects are usually not a problem -- every house will have some. If you have more than you can tolerate, set out sticky boards from a hardware store.  Make sure the area is well ventilated and dry. Seal entry points. Spot and surface applications in crawlspaces and basements with pyrethroids are usually effective for about 6 months.  An outside barrier insecticide treatment may prevent entry into the house.
HOUSE CENTIPEDE Length variable -- 1/8 - 6 inches.  Yellow to dark brown. House Centipedes have numerous legs -- one pair per body segment. Anywhere in the house, but damp basements, bathrooms, damp closets and potted plants are preferred. All centipedes are carnivorous.  They feed on insects and spiders Look in basements and other damp areas. Reduce or eliminate moist areas in the house.  But remember that if you eliminate centipedes, you will need to deal with the insects and spiders upon which the centipedes were feeding. Void treatments and basement/ crawlspace sill plate treatments are generally helpful.  An outside barrier insecticide treatment may prevent entry into the house.
EARWIG 1/4 - 1 inch.  Dark brown in color. Earwigs have a pincher-like structure at the end of their body. Earwigs are active at night.  During the day they hide in moist shady places. Earwigs feed on live or dead plants and/or insects. Look in moist areas of the house. Reduce or eliminate moist areas in the house.  Seal potential entry points. Insecticides inside the house are really not called for in this situation.  If you do use insecticides, more Earwigs may enter the house after the treatment.  An outside barrier insecticide treatment may prevent entry into the house.
DRAIN FLY 1/16 - 1/4 inch.  Dark brown to black This fly looks like a moth. Drain flies are found in bathrooms, and shower stalls.  They are found in the basement around the floor drains and near utility sinks. The adult fly does not eat.  The larvae live in drains and eat the "gunk" around the top of the water line in the drain. If you find adult flies in the house, you can assume that you have one or more infested drains. If you see only one or two adult flies at a time, you can eliminate them with a fly swatter or a squirt of soapy water.  If you have a heavy infestation, you need professional help. If you have access to the drain, the professional can scour the drain with a stiff wire brush to remove the organic material upon which the larvae are feeding.  The professional can apply an insect growth regulator insecticide or a microbial cleaner.
BOTTLE FLY 1/8 - 5/8 inch   with a metallic green or blue thorax. The metallic thorax distinguishes this fly from most other common house flies. At windows.  Flies are attracted to light. The adult fly does not eat.  The larvae feed on decayed meat and dead animals. If these food sources are not available, Bottle Fly larvae will feed on decaying vegetation and garbage. If you see Bottle Flies in your house, you need to inspect for dead rodents or other animals under the house or in wall voids.  Inspect for decaying materials. Remove the food source.  Caulk and seal to prevent wild animals from entering the house attic, basement and wall voids. Insecticides are not called for in this situation.
GROUND BEETLES 1/16 - 1 3/8 inch.  Various colors. Some are brightly colored metallic green.  Others are black. Shape of the body. Almost anywhere. Ground Beetles are predaceous -- they eat other insects and are thus considered to be beneficial. Rarely will you see more than one or two Ground Beetles in your house.  If you try to get rid of them, you will have to deal with the insects that they were attracted to. Exterior perimeter barriers with pyrethroids are often effective at reducing the numbers of beetles that enter the home, particularly in the fall.

Original Publication Date:

Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating. Distributed in furtherance of Acts of Congress of May 8 and June 30, 1914. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age, or national origin.

Disclaimer: Reference to commercial products or trade names does not imply endorsement by University of Delaware Cooperative Extension or bias against those not mentioned.

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