Pest Library

Characteristics

The cornfield ant is a medium size soft-bodied ant that is about 2/25 to 3/25 inch long. It has a dark brown to black coloration and is sometimes mistaken for a carpenter ant because of their similar appearance. However, cornfield ants are smaller than carpenter ants and when they are viewed from the side, carpenter ants have a noticeable notch in the middle section of their body. These ants emit an acid, formic odor when crushed.

Habitat

Cornfield ants are occasional visitors of homes and may be found between cracks in sidewalks, dirt mounds, under rocks or bricks, lush areas, walkways, in lawns, dirt hills, and so on. However, these ants are more of an outdoor ant and will prefer to stay in cornfields than any other places. They do not nest indoors, but may search your kitchen for food. To create nests, cornfield ants will search for moist wood, such as rotten logs or stumps.

Behavior

Cornfield ants ensure that they have a plenty supply of honeydew so they go to great lengths to protect and take care of the oval eggs of the corn root aphids. They will watch over them through the winter months, then transport the nymphs during spring to the roots of weeds until these nymphs grow and produce honeydews. The main tasks of these cornfield ants to these aphids are to become the aphids’ transporter and caregiver. All the while creating an endless supply of honeydew.

Food

These ants can eat both live and dead insects. They can also gather nectar, but they are addicted to the honeydew that are produced by aphids and other sugary insects. When indoors, they will gather sugary food.

Life Cycle

To start new colonies, new reproductives will start to mate late in the summer. Once a queen successfully mates with a male, she will search for a decayed wood to lay her eggs. The eggs will need 2 to 3 months before the eggs reach adulthood. By that time, these eggs will become adult workers that will be responsible in festering their wood much further to create tunnels and galleries for the nest. They will also be responsible in helping the queen with her brood, and tending to aphids for their supply of honeydew. The colony will only have one queen that can live for more than ten years.

Other Information and Tips

Cornfield ants are considered pests as they can destroy wood by adding moisture to the structure. They will do this so that they can further extend their colony. Although these ants are outdoor ants and may just prefer to create nests on already decaying wood, their presence may also indicate the over population and great distribution of aphids, especially in cornfields. Their presence and infestation may hinder the growth of corn and may also destroy harvests.

Indoors, these ants may be prevented by properly eliminating their food sources and sealing cracks and crevices where these ants may enter. If a mound exists near your home, you can use boric acid or boiling water to destroy the mound and eventually kill the queen. Killing the queen will eventually kill the colony. However, if the problem still continues and infestation still exists, contact your local ant control specialist to determine and solve the situation for you.

Photo by Sanja565658 (Own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons / resized from original