You Are Here: Management Updates 2002 Archive April 30, 2002

Date: April 30, 2002
Category: Insects
Subject: Ants

Many turf managers and homeowners have been asking about ants in turfgrass this spring. In most cases the ant in question is 'Lasius neoniger', which has been named the turfgrass ant unofficially. This ant begins nesting and creating mounds as soil temperatures warm in the spring. We have begun to see significant mounding already in southern New England this year.

Turfgrass ants cause several kinds of damage. First, the mounds themselves (which sometimes exceed an inch or two in diameter) are unsightly and can suffocate the turfgrass underneath the mounds of soil. In addition, the soil that has been kicked up into the mound accumulates on the rollers and results in an uneven cut, or abrades the mower blades resulting in dull blades and an uneven cut.

We have conducted several field trials over the past five years, concentrating on chlorpyrifos (Dursban) and the various synthetic pyrethroids. We found that applications of any of these materials in the spring, as soon as mounding becomes apparent, provide four to six weeks of "protection", as measured by reduced mounding activity. However, as the warmer months of summer ensue, subsequent applications usually only reduce ant activity for a couple of weeks. (Dursban is still available for use on golf courses, although the application rate is limited to one pound active ingredient per acre.)

My colleague, Dr. Dan Potter (at the University of Kentucky), has conducted several field trials targeting turfgrass ants over the past three or four years. He recently published an excellent article in Grounds Maintenance (February 2002 issue, in the golf section), describing his results. He has been concentrating on some new products which are formulated as ant baits, which normally are applied by sprinkling granules directly on the ant mounds. (Apparently, broadcast applications over larger areas like golf course fairways would be very expensive.)

Dr. Potter reports that two ant bait formulations look particularly promising and there appears to be nothing on the label to preclude their use on golf courses or other turf areas. (NOTE that updates generated on this web site are directed toward turf managers in Massachusetts. I have not yet confirmed with our Department of Food and Agriculture whether these products have been cleared for use in Massachusetts. Turf managers in other states must check their own state labels to determine which, if any, products are cleared for use.)

Dr. Potter looked at two baits in particular. Maxforce Professional Insect Control Fine Granule Insect Bait (available through Chlorox Company) contains hydramethylnon as an active ingredient. Advance Granular Carpenter Ant Bait (available through Whitmire Micro-Gen) contains abamectin as an active ingredient. Both baits worked well in the Kentucky field tests, but Maxforce appeared to be better suited for use on putting greens because the granules are smaller and darker color, so they are less conspicuous. A small amount of bait, sprinkled around each mound, will eliminate a nest in about two days.

Lasius neoniger workers forage 24 hours a day, so a bait can be applied whenever it is convenient. However, once baits get wet they are less attractive, so do not apply materials before a forecast rain event, and withhold irrigation for at least 24 hours after application.

A few final points - Note that there is another product (Advance Granular Ant Bait) that is very similar in name but not as effective against the turfgrass ant. Also there is another relatively new product under development that contains fipronil. This active ingredient has been shown to be quite effective against the red imported fire ant in the Southeast. A single application in fall to early spring provides control of fire ants for up to a year. Turfgrass ants are also on the label, but our trials in New England thus far have been inconclusive regarding how effective fipronil will be against our ants species.

Ant baits probably hold the key to successful ant control in turfgrass in New England. We will be testing several of these products, along with synthetic pyrethroids, throughout 2002.

- Submitted by: Dr. Pat Vittum