Ants are thriving in my kitchen, my bathroom, and at my office. 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 must include an integrated approach.
Identify the ant
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. To identify your ants, visit the Illinois Department of Public Health: Prevention and Control of Ants website for a visual comparison and descriptions.
The small black ants may be difficult to distinguish. My ant visitors have been identified as odorous house ants. They are small and black, with faint striping on their abdomen, and when crushed they smell like coconut. Odorous house ants nest under rocks and debris but can also nest in the floors and walls. They eat sweets, meats and dairy. My eviction plan included sanitation, exclusion, and baits.
Ant control methods
Cleaning
I started with cleaning out the cabinets, securing better food storage, and running the fan in the bathroom after showers to prevent moisture build-up. Ants use pheromones to mark their trails, so I disrupted the ant trails I could find with a solution of water and bleach multiple times. The water and bleach was a fleeting line of attack, as in a few hours, they returned.
Find the nest
The next step is to find their nest. Many ants enter homes from outside nests looking for food. To find their nest, you must trace the ant trail back to the origin. For most, the nesting sites will be in soil under objects outside like stones, boards, firewood, or blocks. They can also nest in wall spaces and under floors of your home. In the past, I have traced my ant back to the compost bin outside my kitchen window. Currently, the ants are using the structure of my home. Therefore, I will need to repair and caulk cracks that are allowing them access to my home. If it is not clear where the ants are entering, you may treat a one-foot-wide area around the perimeter of your house.
Sweet baits were another part of my eviction plan. Some sweet baits contain insect growth regulators that prevent larvae from reaching adulthood, ultimately killing all the female foragers and starving the nest. Others disrupt the colony functions, the ant's respiration, or are toxic when eaten. If they like the bait, you may see multiple individuals visiting. At this time, you do not want to use bleach water to cover up ant trails. If they do not accept the bait, try another kind. Do not use insecticide sprays or dusts when implementing the baits.
The ants you see wandering around the kitchen are the wingless sterile female workers whose only job is to gather food. They come from a colony of winged female queens and winged males. In June on calm sunny days, they may swarm and aggregate to mate. The winged females leave to find a nest site and the males are left to die. The queen is larger and loses her wings once she has established a nest, and may live for multiple years laying eggs.
Most swarming ants cause concern in homeowners because they believe them to be termites. However, identification between the two is simple. Both termites and ants have two pairs of wings, but ants have shorter back wings and termite's wings are of equal length. Ants have antennae that are in an elbowed shape and have thin waists between the thorax and abdomen. Termites' antennae are not bent, and their waist is broad, keeping a consistent shape down the length of the body.
Outdoor pest management
Recommendations for outdoor pest management from the University of Illinois Extension include applying sprays or granules that contain bifenthrin, cyfluthrin, esfenvalerate, gamma-cyhalothrin, lambda-cyhalothrin, and permethrin for treatment on nests outside.
For baits, look for:
- Abamectin, propoxur, and thiamethoxam. These paralyze pests by interrupting the nervous system.
- Boric acid, dinotefuran, fipronil and indoxacarb. These disrupt ant colony function.
- Hydramethlnon. This disrupts cellular respiration and is toxic when digested.
Whitney Cranshaw, Colorado State University Entomologists suggest baits that contain insect growth regulators (hydramethylnon) as an option. He says it affects growth or prevent queens from producing fertile eggs.
Always with any pesticide read and follow the directions on the pesticide labels before using them.