Heavy rains may bring unwelcome guests into your home

Pavement Ant

Ants may be thriving in your home this spring. They usually enter buildings after heavy rains and persist as long as the environment is to their liking. In the kitchen, they are seeking out sweet treats, and are attracted to the moisture in the bathroom.

Despite ants not causing damage to the home and being beneficial in aerating soils, they are a general nuisance and are easily evicted. The eviction does take time, usually at least 24 hours, and must include an integrated approach.

First, identify the ant. This is an important step as they have different nesting sites, food preferences and control methods.

Some of the most common ants in Illinois are pavement ants, odorous house ants, small honey ant, carpenter ant, large yellow ant, and pharaoh ant.

Odorous House Ant

To identify your ants, visit the Illinois Department of Public Health: Prevention and Control of Ants for visual comparison and descriptions (http://www.idph.state.il.us/envhealth/pc_ants.htm).

The next step is to find their nest. Many ants enter homes from outside nests looking for food. To find the nest, you must trace the ant trail back to the origin, most likely under objects outside the home, such as stones, boards, firewood, or blocks.

They can also nest in wall spaces and under floors of your home. If you have a compost bin, they are also an attractive hide-out. Repair and caulk cracks that are allowing them access. If it is not clear where the ants are entering, you may wish to treat a one-foot-wide area around the perimeter of your house.

The ants you see wandering around the kitchen are the wingless sterile female workers whose one job is to gather food. They come from a colony of winged female queens and winged males. In June on calm sunny days, you may find a swarm where the ants have aggregated to mate. The winged females will then leave to find a nest site and the males are left to die.

Swarming ants often cause concern for homeowners because they believe them to be termites. However, the identification between the two is simple: both ants and termites have two pairs of wings. Ants have shorter back wings than the front, and termite’s wings are of equal length. Ants also have antennae that are in an elbowed shape and have thin waists between the thorax and abdomen.

Sweet baits are another part of an ant eviction plan. Some sweet baits contain chemicals that act as insect growth regulators that prevent larvae from reaching adulthood, ultimately killing all the female foragers and starving the nest.

Others disrupt the nervous system, colony functions, respiration, or are toxic when eaten. If they like the bait, you may see multiple individuals visiting. If they do not accept the bait, try another kind. Do not use insecticide sprays or dust while implementing baits.

Pest management recommendations from the University of Illinois Extension recommend applying sprays or granules that contain bifenthrin, cyfluthrin, esfenvalerate, gamma-cyhalothrin or lambda-cyhalothrin and permethrin for treatment on nests outside. For baits, look for any of the following ingredients: abamectin, propoxur, thiamethoxam (paralyzes pests by interrupting the nervous system), boric acid, dinotefuran, fipronil, and indoxacarb (disrupts ant colony function), and hydramethlnon (disrupts cellular respiration and toxic when digested).

Whitney Cranshaw, Colorado State University Entomologist, suggest baits that contain insect growth regulators (hydramethylnon) as an option. He says it affects growth or prevent queens from producing fertile eggs.


But always remember, with any pesticide read and follow the directions on the pesticide labels before using them.


For questions, please reference your local University of Illinois Extension Office and Master Gardener Help Desk hours. More information on both can be found online at go.illinois.edu/MGHelpDesk.