Fire Ants

I have received a number of calls in the past week regarding fire ants. Big mounds, little mounds, many mounds. Generally, there is no cause for alarm. You just need to know whether to do anything and if so, what. Persons who have severe reactions to stings should not attempt to treat fire ants.

The only mounds that I encourage people to deal with are those where there is likely to be human contact. If it’s across the road or at the edge of the woods, why bother? In fact, there’s evidence that the more we try to control them, the more likely we are to need to control them. Besides that, no one has eliminated them yet in Alabama, Louisiana, Florida, Mississippi, Georgia, South Carolina, and other states. And they've had a lot more practice. I don’t expect to eradicate them here.

If you’re worried that a mound a hundred yards away may infest your lawn, it’s just as likely that a mound a mile away will be the source of your problems. Every spring, virgin queens leave a mound and mate in the air. Depending on which way the wind blows, the mated queen will land somewhere within a couple of miles and attempt to start a nest.

By some measures native ants kill as many as 90% of these mated queens before they start a colony. Most ants out there are your allies in defending territory. Indiscriminant treatment of ants may actually tilt the balance in favor of fire ants.

For those queens that do start a colony, it often takes several months before there are enough worker ants to make a visible mound. So if the queen mated in the spring, it would not be surprising to see a lot of small mounds show up from late summer into fall. It’s not necessarily because of another mound nearby or because your efforts with that mound have failed. It’s predictable for small mounds to show up now.

If you have a mound in areas that require treatment (areas with high potential for human contact), you should avoid disturbing the mound. When the mound is disturbed, worker ants remove the queen from the mound by way of underground tunnels, usually in less than a minute. With repeated disturbances, they may completely relocate the mound.

The easiest treatment strategy involves use of a bait with very low concentration of active ingredient. Baits should be applied near but not on the mound. The ants like to think they have discovered the stuff themselves. Baits should be purchased in an air tight container, kept dry, and used under dry conditions. Moist bait becomes rancid, and ants won’t take it.

When the ants do take it, they must live long enough to take it back into the mound, pass it along to another ant that will pass it along to another ant and so on. If it worked quickly, it would not get past their defenses. By working slowly, they have time to feed it to the queen. The queen eventually dies and quits laying eggs. The mound then slowly wastes away over several weeks as the rest of the ants die.

Fire ant insecticides should not be applied close to wells or surface waters. For those situations boiling water (with its own hazards for users) may be used to get them to relocate.

All insecticides have restrictions about where they can be used. Many can not be used in food crops. Check the label carefully before purchase to make sure it fits your needs. There are a number of bait products available in the market place including at least two that bear the seal of the Organic Materials Review Institute (OMRI).

Determine which mounds need your attention and deal with them systematically. Leave the others alone. And get used to having some mounds around. Teach the children about them. They are very industrious insects with good work ethics and home loyalty. Good lessons for us all.

alcooke

Al Cooke
Extension Agent - Agriculture
Chatham County Center
North Carolina Cooperative Extension Service
N C State University
PO Box 279
Pittsboro, NC 27312
919.542.8202, FAX 919.542.8246
al_cooke@ncsu.edu http://www.ces.ncsu.edu/chatham/staff/acooke/home.html