Common names: Cut Ant, Cutter Ant, Fungus Ant, Parasol Ant, Texas Leaf cutting Ant
Scientific name: Order Hymenoptera, family Formicidae, Atta texana
Size: Adult--1/16" to 1/2"
Identification: Light to dark reddish brown ants. Antennae are long and elbowed without distinct club. Three or more pairs of sharp spines on the waist. Can be seen marching along well-worn trails. The trails going back to the mound will have large pieces of leaf tissue.
Biology and life cycle: Complete metamorphosis. Swarm from early April to early June. Workers travel on well-defined trails. They cut leaves and buds and take them back to the mound. They also gather some seed. Most active from May to September, foraging at night. Mounds are huge. They use the organic matter to build a compost pile underground. They feed on the fungus that grows from the compost. Queens can live ten years or longer.
Habitat: Nests in well-drained soils. All vegetable and landscape plants.
Feeding habits: Feed on fungus that grows on the compost pile made in the mound. The ants use all kinds of plant materials to make the compost piles. Howard's listeners report that these ants even use the berries and leaves of mistletoe.
Economic importance: Leaf cutting ants will defoliate and kill food and ornamental plants. One of the most difficult ants to control.
Natural control: Lizards and birds love to eat 'em. Thick mulch around all plants helps. Beneficial nematodes help control all pests that live in the ground.
Organic control: Treat the mounds with plant oil products such as Eco-EXEMPT. The best solution may be to spread wetable sulfer to the surface and water it in.
Insight: These ants are master compost makers and mushroom growers. Aggressive ants that strip the foliage of plant and take it into large underground nests where the organic matter is composted in order to grow a fungus which is used as their primary food source. Control is difficult. Biodiversity helps, and mulching all bare soil helps, but drenching the mounds with citrus-based products is the best method to kill the ants. Applications of beneficial insects also help.
We are getting a lot of questions on this ant. I have read what is
available on the web and reflected some more on my experiences. I remember
an important behavior. I did two things:
1. Sprayed the marching path, tree trunk and both gathering piles with EcoSMART. This killed a lot of the gathering ants. I read this post - it is just an assumption - that the composting ants from the colony took the leaves with ECOSMART (once it dried) in to the mound and the EcoSMART product messed up their fungal growing operations.
2. Drenched (power sprayed or injected) the mounds with a hard stream - like you recommend - that may have penetrated far enough to mess with their fungal growing operations.
Leaf cutter on saw dust.