Rain is always welcome despite its unexpected consequences, such as the development of fire ant mounds.
Although rain does not produce more fire ants, it does boost the number of fire ants that are evident in a specific area. Suddenly, their activity is more pronounced.
Ants that are buried deep inside colonies move to the surface to escape the floodwater that rushes into their habitat in the aftermath of a heavy rain. The ants quickly reestablish their habitat at surface level. So, while colonies already exist in your yard, you may not notice them until the ants surface and build mounds in lawns, garden beds, plant containers, around trees and beside walkways or patios.
While many native ants are beneficial, red imported fire ants are bad news. In Texas, these pests cause an estimated $1.2 billion in damage annually. They pose a serious health threat to plants and animals. Not only do they aggressively sting humans, they kill baby quail, injure calves and harm most living things that come in contact with them. They are residents by accident, having come to the United States aboard a ship from South America.
NO DANCING AROUND FIRE ANTS
According to the Texas AgriLife Extension, fire ants can be controlled with the Two-Step Method. When implemented properly, this method provides excellent fire ant management in landscapes. The first step is to broadcast fire ant bait according to label directions. Use a spreader and cover your entire lawn/landscape. Apply bait at a time when the fire ants are actively searching for food. Ants will collect the bait particles as they forage, and then carry them to all nearby colonies to share with other fire ants and queens in underground nests.
Baits consist of food combined with a slow-acting insecticide. Because bait is taken directly into the colony, the product needs only to contain a very small amount of pesticide. Baits may also be applied directly to fire ant mounds, but in order to affect colonies that are not visible, it is best to treat the entire yard.
The second step is to directly treat ant colonies that require immediate attention, such as mounds located next to your home or in high-traffic areas. You have several options including: granular products, liquid concentrates, dusts, baits, naturally derived insecticides or shoveling. Sprinkle granular products that contain insecticides on top and around the mound, and then water in the product using a sprinkling can and 1-2 gallons of water. Liquid concentrates are mixed with 1-2 gallons of water and applied directly to the mound. Dusts are sprinkled lightly over the mound without watering.
Fast-acting baits may be used as direct-mound treatments. These are especially good for treating colonies that may extend underneath pavement. Naturally derived insecticides are available in many formulations. They may be liquid or granular and are typically applied with water. Always follow label directions when using any product.
The last option is shoveling. Simply remove the mounds to less populated, less vegetated sites. Once moved, douse mounds with soapy water. Beware of bites when shoveling, especially if you are allergic to fire ants.
Baits will not kill fire ants overnight. Control takes 2-4 weeks. Products containing indoxacarb, hydramethylnon and spinosad generally produce the quickest results. Baits containing insect growth regulators require 2-6 months for control, but they only require reapplication every 1-2 years.
TEST FOR FRESHNESS
To ensure success, use fresh products. Preferably, use bait from an unopened container. Once opened, the bait should be used within two months. Unopened containers have about a two-year shelf life. To test bait for freshness, sprinkle a small amount next to an active mound. If the bait is fresh, fire ants will pick it up within 30 minutes.
If you are not sure if fire ants are actively foraging, place a small amount of fresh bait (or substitute potato chips) next to a mound. If the ants begin removing the food within an hour, it is a good time to begin the Two-Step program.
Do not water the lawn after applying baits and do not apply baits if rain is expected within eight hours. During hot weather, apply baits only in the evening. When daytime soil temperatures exceed 90 degrees, baits applied during the day quickly lose their effectiveness. In summer, fire ants forage mostly at night.
Always respect the environment when ridding your property of fire ants. Do not use gasoline or other petroleum products as control substances. They are highly flammable and dangerous to the environment. Do not leave insecticide granules on pavement after application. Granules tend to wash into waterways causing pollution. When disposing of pesticides, follow label directions. Never pour them down the drain, as they are not easily removed by wastewater treatment systems. Pesticides that get into waterways will kill fish and other wildlife.
Resource: Texas Imported Fire Ant Research and Management Plant
For answers to your horticulture questions, please call the Texas AgriLife Extension, Hood County at 817-579-3280 and ask to speak to a Master Gardener or visit the website at hoodcountymastergardeners.org.