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Michigan State University Extension
Home Maintenance And Repair - 01500544
06/24/03

Carpenter Ants



The presence of carpenter ants is usually a symptom of a problem a water leak causing wet/punky wood. Therefore, it is important to determine the reason the ants are nesting in the structure, than to kill them. Your home is much more at risk from water damage, which attracts carpenter ants, than the ants themselves. Do not be pressured into buying a long-term spray control program by a pest control company that does nothing to locate the nest and link the symptom to the cause.

Carpenter ants are common invaders of dwellings in Michigan. These ants are opportunistic feeders and invade households looking for food sources; primarily in the kitchen and areas where food is eaten or stored. Like most ants commonly found around the house, carpenter ants prefer sweet and greasy foods.

Prevention of a carpenter ant infestation requires that you do at least two things: maintenance of the structure to deny suitable habitat and maintenance of the structure to deny access.

Periodically inspect your dwelling for water damaged wood and take the appropriate steps to correct the problem. Take special care to carefully inspect areas where water and other pipes go through walls, base of toilets, around bath tubs and the base of shower stalls.

Regularly caulk, weather strip or otherwise repair openings to the out-of-doors such as around window panes, where pipes go through walls to the outside and the basement, and door jambs. Check your roof for water damage under shingles and the slashing around chimneys, standpipes, and other roof and bathroom vents. The use of a bait will lure the ants to feed and you will then be able to watch the ants come and go and ultimately determine if they are coming from the outside or have a colony in your dwelling.

Carpenter ants like sweet and greasy foods. Our bait recipe is two parts jelly or jam an one part canned dog or cat food (the cheaper the better). The portion doesn't need to be more than a half a cup. Situate the bait in the area where you have been observing ants, but safe from pets and children. The ants will start coming to by your bait. Observe where they are going. When you see that they are regularly feeding on your bait it's time to change the recipe. Mix a new batch of bait, but now mix boric acid in with the pet food/jelly mixture. The proper proportion is a tablespoon to every cup of mixture. The ants will carry the "poisoned" bait back to their colony, pass the food around, and eventually the colony should be destroyed.

Indoor formulations of chlorpyrifos can be applied to areas where nests have been found. Great care should be taken when using these poisons in the home. Read and follow instructions on the pesticide label. Heed all warnings. Do not use these materials in your home if you have small children, fish in an aquarium, or pet birds. Check with your physician if you have any concerns regarding your personal health risk. Other recommended indoor pesticides are propoxur RTU and baits:
hydramethylnon and propoxur and boric acid.

If you choose to use an insecticide out of doors, a diazinon 25% EC formulation sprayed completely around the outside foundation and adjacent one foot of soil is suggested.

If you have taken all of the steps to prevent or eliminate these insects through sanitation and/or an application of insecticide and still seem to have an infestation, you may have to implement a more vigorous control program or consider hiring a professional service.

For a complete listing of suggested control options for all home, yard and garden insect pests contact your local Extension Service, found under local government in the phone book.

Read and follow instructions on the pesticide label. Heed all warnings. Check with your physician if you have any concerns regarding your personal health risk.

References

Revised by Tom Ellis, M.S., Department of Entomology

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