Common Home-invading Ants

Common Home-invading Ants

Odorous House Ants
Photos were taken by Erin Bauer, UNL Extension

Even though bed bugs are on everyone's mind, the Extension office receives more consumer calls about ants than any other group of insects.

In Nebraska, there are about a dozen species of structure-invading ants. Results of a nationwide pest control survey indicated odorous house ants and pavement ants are two of the top three problem ants. These ants are found in Nebraska.

Odorous house ants and pavement ants are similar because their workers sometimes invade homes for food and are attracted to sugary substances, particularly in the kitchen. Outdoors, these ants feed on honeydew produced by plant sap-feeding insects such as aphids and mealybugs. They often forage indoors when they can't find food outside. A good example of this is after a period of rainy weather when aphids have been washed off plants. Once aphids re-colonize, these ants often disappear from the indoors, because their preferred food is again outdoors.

Odorous house ants. Odorous house ants are small ants (1/10 inch) and dark brown. With a hand lens or microscope, you can see they have one node that separates the abdomen from thorax. When you look at them from above, the node is hidden. They are easiest to identify by their smell - similar to slightly rancid coconuts - when crushed.

Odorous house ants usually nest outdoors in the soil under stones, logs, mulch, debris, and other items. They are the most invasive ant species we have in Nebraska. If you eliminate a colony from an area, within a few months, another colony may move into the area.

Odorous house ants can nest indoors in wall and floor voids, but generally a moisture source must be present for ants to live there. Winged ants found indoors are a sign of in indoor colony.

Pavement ants. Pavement ants are small, dark brown ants, about 1/8 to 1/10 inch long. They have a two-segmented node between the thorax and abdomen. Pavement ants have a single pair of spines on their thorax. The key feature which distinguishes them from other two-node ants is the sculptured grooves on their head and thorax.

The pavement ant gets its name from its habit of nesting under sidewalks, driveways, patio pavers, and other locations. The common "ant hill" between sidewalk squares is usually from pavement ants.

Management. Effective ant control requires treating the colony to eliminate the queen and all the colony members. Odorous house and pavement ant workers deposit a trail pheromone on the substrate to let other workers know about food resources. Before you take control actions, follow these trails to try to locate the colony.

Treating ant hills. If you find it, the simplest method of eliminating an ant colony in the yard is to pour a small amount of a diluted insecticide down the hole, following the information on the pesticide label. This is called a drench treatment.There are a number of granular ant baits that usually are used outdoors around ant hills.

Liquid bait. Sometimes ant colonies cannot be found easily. Both odorous house and pavement ant workers often are attracted to syrup baits for sweet-loving ants. These baits should be placed near where ants are seen or on or along trails. Place the liquid syrup on small pieces of cardboard, index cards, or painter's tape. You'll want the syrup to bead up rather than soak into the paper. Some baits come inside plastic boxes or metal traps, but many people who buy them often find the ants do not seem to be able to locate the entrance to the bait box. Ants prefer a liquid diet, so if the bait gets dried, replace it.

Don't use insecticide sprays in addition to bait treatments. The goal of baiting is to feed as many ants as possible so they take it to the colony to feed other ants. If an insecticide treatment kills ants, they won't be able to get back to the colony so you are counteracting your baiting effort. Be patient. It may take several weeks or more to get rid of the ants using baits.

Perimeter sprays.Do-it-yourself sprays around the house perimeter may be helpful in keeping ants out of the house, but these products won't eliminate the colony.

If you are unable to control the ant problem or to find the location of the colony, hire a pest control professional to do a Termidor treatment for you. When applied to ant trails or entry points, the active ingredient, fipronil, adheres to the ant body. It transfers to other ants in the colony. Termidor is a professional use product and can be used only twice a year. It cannot be used indoors.

Pavement Ants
Barb Ogg
Emeritus Extension Educator, Entomology
Barb Ogg shared her love of entomology with clientele throughout Nebraska for many years through Nebraska Extension. Barb retired in 2015.

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