Leaf cutter ants are not an incredibly common pest, but those that have them, know how destructive they can be. Seemingly overnight entire gardens can be stripped of leaves, trees completely defoliated, and flower beds destroyed.

During cooler weather, leaf cutter ants start to become a little more active. Leaf cutter ants will strip the leaves of any type of plant, but seem to prefer citrus and pine if given a choice. If you have a leaf cutter ant problem, and are thinking about planting lemon or orange trees, be prepared for frustration!

Leaf cutter ants are interesting ants that do not actually consume the leaves they defoliate. They take the cuttings back to their nest, chew on the ends, and the saliva promotes fungal growth. Leaf cutter ants actually eat the fungus, not the leaves.

There are very few options for leaf cutter ant control. Liquids and dusts applied to plants will only affect those ants stripping the leaves - you will never eliminate the colony this way. Baits are a much better option, because they are taken into the nest and feed to the queens. The baits also spread throughout the colony and more of the colony dies. There are currently only two baits available: Amdro Ant Block and Grant's Ants. Both of these baits are the same, they just have different names, and either one should work equally well. I have had better luck finding Amdro Ant Block in urban areas (hardware stores, garden centers), and Grant's Ants in rural areas (feed stores, farm and ranch stores).

Crater-like leaf cutter ant mounds. Photo: citybugs.tamu.edu/

The key to controlling leaf cutter ants depends just as much on how and when you apply the bait as what you use. First, find the "town" or area of crater-like mounds. This is their nest, and this is the best place to treat. Apply the bait randomly as per label recommendations. You can either use a hand held spreader, or the sprinkle top on the container to dispense the product. Never place bait directly into the holes or kick the holes in: this will only make them move and avoid the bait. If you cannot find the town, find a trail of ants, and sprinkle bait along their trail.

The best time to treat is when you see leaf cutter ants actively foraging. After you apply the bait, watch them for a while to see if they pick it up. If they avoid the bait, you will not have good results. If they pick up the bait, you will have a drastic reduction of ants within 2-5 days.

These applications seem to last at least 6 months in most cases, and after 6 months the leaf cutter ants start to resume some activity. They will be very sluggish and seemingly inactive. When they become destructive again, reapply the bait for another 6 months of control.

IPM Program Specialist and Entomologist, Molly Keck
mekeck@ag.tamu.edu
3355 Cherry Ridge, Suite 212
San Antonio, Texas 78230
210/467-6575