County Gardeners Extension Express
Fire Ants in the Vegetable Garden
Fire ants first entered the United States about 1918, near Mobile, Alabama and reached Mississippi around 1930. They now occur over much of the Southeast. There are two species of fire ants in the state. Red imported fire ants are the most common, but some areas have black imported fire ants, or hybrids of these two species. These two species are similar in biology and behavior.
Fire ants are social insects that nest in the soil in large colonies that contain tens of thousands to more than 200,000 ants. It takes several months for a colony to get large enough to build a mound large enough to be noticed in the average home lawn, which is where they may be discovered more frequently compared to your vegetable garden. For every easily visible, large mound there are usually many younger colonies that are still too small to produce visible mounds. But once a young fire ant colony is well established and has a few thousand workers, it can quickly develop into a mature colony containing tens of thousands of ants.
Fire ants are the ant species most common in Mississippi gardens. Besides their stings, which interfere with tending and harvesting the garden, fire ants also damage some vegetables, such as okra and Irish potatoes. Sometimes fire ants reduce stands of corn and other crops by eating the germ (innermost layer of a corn kernel) of newly planted seed. Fire ants nest in mounds, which may be within the garden, or foraging workers may enter the garden from mounds around the outside of the garden.
Granular baits are effective fire ant control tools but are slow-acting. Most of the fire ant baits labeled for use on home lawns may not be applied directly in the garden area so please read and understand the label and its limitations. But you can apply labeled fire ant baits to the lawn area immediately surrounding the garden to help reduce the number of ants that invade the garden. For best results, treat two to three times per year, in early spring, midsummer, and/or fall.
Some fire ant baits containing the active ingredient spinosad may be applied directly to the garden and are even approved for use by organic gardeners. Spinosad, permethrin, and carbaryl insecticides can be applied to problem mounds within the garden area by using the soil drench method. Mix and apply according to directions on the label. Use 1 to 2 gallons of drench per mound. Using the soil drench method with an approved vegetable insecticide and applying an approved fire ant bait in the areas surrounding the garden will help you get control of fire ants