Ag Biz News Column
County Extension Agent—Ag/NR
Texas Leaf-Cutting Ants
Have you been seeing large, winged ants lately? These winged species are the male and female reproductive species of the Texas leaf-cutting ant. The Texas leaf-cutting ant causes economic damage to forest lands, landscapes, and even some agricultural crops in Texas. These ants are also referred to as town ants, cut ants, and night ants to name a few.
The Texas leaf-cutting ant is rust brown in color and ranges from 1/16 to ½ inch long with three prominent pairs of spines on the thorax. The queen is much larger and can be as long as ¾ of an inch long. Leaf-cutting ants are social ants.
In April through June, the winged ants leave the colony on mating flights. This usually occurs on moonless nights. The virgin queen ants carry a small piece of the fungus from the parent colony in a small cavity inside her mouth. After mating, the male dies. The queen then loses her wings and digs a small tunnel or gallery in which she will begin laying her eggs. She will also begin culturing her fungus garden. Once the eggs begin to hatch, workers will begin going out and gathering foliage of various plants to continue her fungus culture. Colonies can survive for many years and can contain as many as 2 million ants. Their nests may be 15 to 20 feet deep underground with numerous chambers and tunnels. When I was working on my Master’s degree at SFA, we dug down as far as a backhoe would literally reach in a leaf-cutting ant colony and still did not get to the bottom of the colony. Tunnels were everywhere.
The Texas leaf-cutting ants have mouthparts that are for chewing. Worker ants remove leaves and buds from weeds, small grains, forage and turf grass, fruit and nut trees, and many other ornamental plant species. Pine trees and pine seedlings are targeted when other plant material is scarce. Worker ants can travel more than 600 feet or more along foraging trails that they carry back foliage to the colony. Inside the colony, all the ants feed on the fungus grown on the leaves gathered.
Worker ants can bite. During summer months, these ants feed almost exclusively during the night. Other times of the year these ants forage during the day when air temperatures range between 45 to 80 degrees. These ants are usually inactive on cold, wet or cloudy days.
How can I control these ant species? Control of the Texas leaf-cutting ants can be difficult. In some instances, individual plant treatments with dusts and granular products can help but must be applied frequently. The individual plant treatments do little to eliminate the underground nest. Due to the leaf-cutting ant primarily eating fungus they grow, they do not respond to most ant baits used in the home landscape for other ant species.
The Texas Forest Service has conducted research to help control these ant species especially in a forest management setting. From their research, newly labeled products are now available in forest management areas. Be sure to read and follow all label recommendations when using any product to control this or other insect species. In agricultural sites, control is limited. In the home lawn, landscape, and residential site, some broad-spectrum ant specific baits are available. Again, due to their foraging, diet and size of the colony, control is difficult.
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