Description of field ants
The name field ant is used for a large group of ants commonly found nesting in fields, meadows and lawns in Iowa. Field ants are probably our most commonly observed kind of ant. They are primarily medium sized (about 1/4 inch long), brownish-black ants, but they show considerable variation from one species to the next. Field ants nest in the soil in moderately large colonies. They are scavengers and feed on other insects and nectar from flowers. Field ants do not normally nest indoors but the workers frequently forage indoors for food and create an annoyance by their presence.
Damage caused by field ants
Field ants are commonly noticed during their swarming flights in the fall of the year. Large numbers of yellowish-brown, winged ants emerge from an underground colony and crawl around on the ground, trees, shrubs or buildings near the nest entrance before flying off to attempt to establish new colonies. These winged ants are harmless but create concern and some annoyance if they enter houses during their swarming activities. Swarming is a temporary, natural event and is not a permanent nor major problem.
Management of field ants
The need for control of field ants depends on the time of the year and the situation where they are encountered. If invading workers are a problem in the house during spring or summer, a barrier spray treatment around the outside of the house is suggested. Pyrethroid or carbaryl insecticide labeled for use against ants outdoors can be used in a 5 to 10-foot wide band next to the foundation according to label directions for this treatment. There is little justification for controlling winged swarmers in the fall of the year. However, direct nest treatment with any of the insecticides listed above may reduce the annoyance. For more information please read this article.
Do you live in Iowa and have an insect you would like identified?
The Iowa State University Plant & Insect Diagnostic Clinic will identify your insect, provide information on what it eats, life cycle, and if it is a pest the best ways to manage them. Please see our website for current forms, fees, and instructions on preserving and mailing insects.
Contact information for each states diagnostic laboratory for U.S. residents. If you live outside of Iowa please do not submit a sample without contacting the Plant & Insect Diagnostic Clinic.