The Plan for Managing Crazy Ants in Louisiana

Paratrechina longicornis, a common species of crazy ant
The plan is very simple but will require extensive coordination. The entire infested area must be addressed simultaneously. Below is a summary of the plan:

1. Accurate identification.

2. Sanitation – elimination of nest sites.

3. Block the ants’ access to food and eliminate visible nests.

4. Let them eat bait – capitalize on their cooperative foraging to deliver small doses of toxicant to the colonies.

Identifying Characteristics of Crazy Ants

This reddish brown to black ant is seen in disorganized foraging trails going into houses and trees. Legs and antennae are usually longer than the body, which is characterized with coarse hairs. This ant has a one-segmented petiole and 12-segmented antennae. They do not possess a sting but can spray formic acid. Hairy crazy ants, which entered Louisiana during or prior to 2010, require a specialist to identify them correctly.

General Information about Crazy Ants

Crazy ants form large colonies, which often have multiple queens. The monomorphic (similar in size) workers are omnivores and will feed on dead insects and honeydew. Since they do not sting, they are considered a nuisance and not a direct threat to human health. They enter houses, businesses, cars, boats and recreational vehicles en masse for food, water, and shelter. They nest in a variety of habitats, such as under objects in the yard, in potted plants, in compost piles and in soil. Crazy ants can be difficult to control because they are nomadic and form new colonies by budding. In fact, the only way to manage them involves areawide or communitywide treatment projects. This approach is similar to that used for Argentine ants.

The Problem

Hairy crazy ant populations reach extremely high numbers of individuals and may overwhelm large areas. They short out electrical circuits, kill bees and may disrupt ground-nesting wildlife. They are most problematic because they enter structures en mass and irritate humans. They are easily transported via nursery stock, turfgrass and movement of soil and mulch. These attributes are similar to those of Argentine ants. In the areas of Louisiana where Argentine ant populations are large, radical reductions in biodiversity of ants and other arthropods have been observed.

Areawide Management Program

Areawide or communitywide management of fire ants and Argentine ants has been successful in Louisiana in the last nine years. The information presented here is based on modifying the techniques that were developed for Argentine ant management because of the ants’ similar biology. These techniques are in early stages of testing on hairy crazy ants in Louisiana because of their recent entry into the state. However, Argentine ants have very similar biology, and the following recommendations are the result of five years of research by L.M. Hooper-Bùi. The following protocol must be done with most people in the area at the same time in order to be successful. Hooper-Bùi suggests that early April (around tax day) is the best time for this protocol to be implemented, but this can be done at any time. However, it will be more successful if the hairy crazy ant populations are disrupted before they get too large and out of control. It is recommended that the Louisiana Department of Agriculture and Forestry work with communities to tackle this problem together on an areawide basis to achieve radical suppression. If new infestations are observed and treated early enough, the hairy crazy ants may be eliminated, and the ant and arthropod biodiversity can be preserved.

  1. Monitoring and Identification. Correct identification of the hairy crazy ant is important. Insect diagnosticians in the Louisiana State Arthropod Museum can provide positive identifications. Once the ants have been identified as hairy crazy ants, the following integrated pest management (IPM) protocol should be followed.
  1. Sanitation. Clean up the area. Remove harborage that provide nest sites such as fallen logs, children’s toys, overturned boats, pots with soil, free-standing basketball nets, woodpiles, lawn tools and other items that crazy ants can nest in and under. These items also provide extra heat for rapid development of colonies, which can quickly overwhelm the area. Trim plants and trees so that they do not touch the structures. Ants can gain entry into structures from tree branches that are simply close to the roof. Crazy ants are attracted to spaces that are moist and wood that is rotting. Rotting wood provides moisture and heat needed for colony reproduction. To prevent infestation, consider replacing rotting siding, window sills, and door frames on homes and outbuildings. Look for ground-to-wood contact around structures and find a way to eliminate this problem. The next time it rains, walk around the property and look for water that may pool or contact the wood on the structures. Eliminating water-soaked wood will help prevent ant infestation of homes and siding.
  1. Disrupt the foraging into trees and houses, and suppress ants in visible nests. Using a contact insecticide, such as a pyrethroid or an organophosphate in a hand-held pump or backpack sprayer, apply a liquid barrier around trees approximately 2 feet up and 1 foot out from the base of the tree on which the ants are trailing and around houses or other structures that are infested. Make sure to treat all surfaces of the bark of the trees, and try to treat all the trees on your property at the same time. If possible, drench with contact insecticides any nests of crazy ants. This will partially disrupt the nesting and foraging and allow the rest of the treatment to be successful.
  1. Let them eat bait. Many of the nests are not detectable by humans, so the ants will do the work to suppress their own nests. This process capitalizes on the ants' amazing foraging behavior to gather a palatable bait that contains a small amount of insecticide. Broadcast a granular bait such as Max Force in early spring. (It is important to use the fine granule version with either hydramethylnon or fipronil as the active ingredient.) Colleagues in Texas report that the hairy crazy ants are attracted to Whitmire Advance Carpenter Ant Bait, but have had limited success. This is a granular bait formulated for the much larger carpenter ant. One way to increase the success of the bait is to grind the bait into smaller particles that can be more easily taken by the crazy ants. Hooper-Bùi has published results on particles size of baits, and simply grinding the bait to a more preferred particle size often solves problems. It is important that you use fresh bait and apply it when the ground is dry and no rain is expected for 24 hours. Broadcast bait over the entire infested area. Liquid baits can be tested for palatability and offered in bait stations. Hooper-Bùi’s experience with other species of crazy ants indicates that liquid baits can be effective. Ants will usually visit liquid bait stations when they need sugars or carbohydrates and may come to them intermittently. Be sure to place the bait stations out of direct sunlight; ants will not enter a bait station that is hot.


It is important that insecticides not be sprayed or broadcast in a way that they contact the water in a reservoir or other waterway directly or through runoff. Runoff of pesticides applied too close to water may occur if it rains too soon after application or if insecticide label instructions are not followed precisely. Also, please keep all insecticides and baits out of reach of children. Read, understand and follow all insecticide label instructions. Apply only what is suggested; more is not better and will result in wasted time, product and money.

Tips for success.

Be sure to use fresh bait that has not been stored with other insecticides or chemicals, such as gasoline. Avoid cigarette smoking while applying the bait as the ants to do not like the smell and it is unhealthy. Try to apply the bait as evenly as possible with a hand-held spreader.
10/2/2009 11:27:10 PM
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