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Leaf Cutter Ants

Expanded Question:

They are a long established problem here near Houston, TX. and are once again destroying everything I plant. I've been spraying the area with Malithion and directly down the holes
(their feeder holes) Most instructions for exterminating them is about treating the mound. Frankly I can't find their mounds, only the feeder holes that are always 10-20 feet from their target. How far away could the mounds be? HELP!


Answer:

Control of Texas leaf cutting ants is difficult. Although plants can be protected temporarily using powder or granular formulations of contact insecticides like acephate (Orthene®), carbaryl (Sevin®) or permethrin, these treatments must be reapplied frequently. Also, plant applications do not eliminate underground colonies. The large size and complexity of leaf cutter ant nests makes it difficult to obtain good control with dust, liquid and granular insecticides. Because these ants eat only the fungus they cultivate, they do not respond to most other ant baits, such as those labeled for fire ants. A special formulation of hydramethylnon, Amdro® Ant Block, is currently the only widely available product that is labeled for control of leaf cutting ants. This product can be used on most sites such as lawns, landscaped areas, golf courses, ornamental gardens, and other none cropland areas such as roadsides, commercial grounds, etc.
      

According to Texas Forest Service tests, hydramethynon bait is about 30% effective in eliminating colonies with a single application. Follow-up applications may be needed, especially for larger colonies. This bait should also not be stored for extended periods of time due to a relatively short shelf life. Shelf life may be extended by refrigeration. This product should be available through a variety of stores, including Ace Hardware and WalMart.
      

The most widely available consumer products for leafcutter ant control include acephate dusts and insecticide granules labeled for general ant mound control. These products should be applied to all nest openings according to label directions. If possible, dusts should be blown into nest openings using a garden duster or squeeze bottle. It may be difficult to obtain complete control of large, well-established colonies using these products.



Since you can't locate the mounds, I copied the above information for your consideration.  I would recommend watching the activity, as ants travel back and forth.  You should be able to follow ants carrying leaves back to their mounds. 



Natural approaches that you might use are as follows:
 Spread wettable sulfur powder over the mounds and water in.  You can use Rosemary oil soaked into the mounds.  Obtain a product known as Eco-EXEMPT IC that contains 10% Rosemary and 90% of a combination of wintergreen oil plus mineral oil.
 There is a vine known as Tanaercium nocturnum, Bignoniaceae, where when scrapings are applied to the top of the mound, ants are killed instantly.  Google all the above information to locate sources to obtain the suggested material.

Leaf Cutter Ants collect vegetation, in order to compost within their mounds, a fungi which the ants require as their food substance.  No fungi-no ants.  Much research is being done on this subject.  Colonies produce upwards to a million ants.  Such numbers can defoliate an entire grove.



I sincerely feel for you.  You have a challenge, but then, all gardeners fight the elements.  Use this information to combat, and with battle experience, and never say,"I quit", you can win.



Good luck Robin,



George Manning


Consulting Entomologist

Pest Control Chicago
American Pest Solutions

 

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