Reduced-risk chemicals control Northeast’s peskiest pests

In his 30 years as an entomologist working to control the pests that attack turf, Professor Stan Swier of the University of New Hampshire has never been so optimistic. The reason? Reduced-risk chemicals, new formulations that control pests—even the Northeast’s most serious ones—while limiting damage to soil, water and animals.

Three groups of pests

In the northeastern United States, says Swier, the number one turf pest continues to be grubs. Primary culprits are the larvae of the European chafer, Japanese beetle, Oriental beetle and Asiatic garden beetle. Where grass is cut to less than 6/10 inch, such as golf courses and around tennis courts, the number one pest is now the annual bluegrass weevil. Ants and ant control also remain a challenge.

Photo courtesy of NYSAES.

Evil weevil

A serious problem because it causes devastating damage on golf courses, annual bluegrass weevil devastation occurs from Maryland north to Maine and from Maine west to Ohio. It is just beginning to be seen in the South and Midwest.

In late April, overwintering adult annual bluegrass weevils move from tall grass or woods on the side of golf courses into the shorter grass of greens, tees and fairways. The adults are small and not easily spotted, especially in cooler weather when they stay down in the turf. The newly emerged adults mate and lay eggs in the stems of grass blades. There, the larvae hatch and feed, eventually descending to the base of the stem. As large larvae, they feed on the crown, killing the grass plant. Larvae crawl from crown to crown, each larva having the capacity to kill more than one grass plant. Larvae feed through May and early June. By early or mid-June, depending on the weather, affected grass will begin dying. Once the grass starts dying, the annual bluegrass weevils’ damage has been done.

In springs with alternating periods of warm and cold weather, there may be two or even three periods when adult annual bluegrass weevils emerge. Because of the prolonged adult emergence period, control of this pest is difficult. A single pyrethroid spray, having only a two-week residual, is not effective. This, together with the added complication of multiple microclimates within a single golf course, has resulted in the tendency to spray two or more times in order to catch early and late-emerging adults. Spraying pyrethroids more than once a year over many years has resulted in the development of some annual bluegrass weevils’ resistance to pyrethroids. To date, this resistance has been localized on a few golf courses in Connecticut.

Among the pyrethroids used to fight annual bluegrass weevil:

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Reduced-risk products

Some newer, reduced-risk chemicals may help control annual bluegrass weevils and other insect pests.

DuPont’s Acelepryn is effective against the annual bluegrass weevil and other pests, including bluegrass billbug and caterpillars. Classified as a reduced-risk chemical, it is now being reviewed by the Environmental Protection Agency (EPA) with registration anticipated this year. It works by depleting calcium in insects’ muscles. Because they have not previously been exposed to it, insects currently have no resistance to this class of chemistry.

Grub damage to an athletic field.

One of about 50 university researchers around the United States to test this anthranilic diamide class of chemistry, Swier has been working with Acelepryn since 2004. In a research setting, he found that it had a long residual period, killing cutworms for 118 days, but he does not know whether or not similar results will occur in all locations.

Annual bluegrass weevildamage on a golf course. Annual bluegrass weevil larva.

Other low-risk chemicals relatively new to the market include Conserve, a microbial from Dow used to control caterpillars and the larvae of annual bluegrass weevil, and Provaunt (active ingredient indoxacarb), a Dupont product. Provaunt, Swier says, “is a great larvicide.” It should be applied at the first sign of cutworms feeding. Birds will often help identify these areas. Provaunt may be used three to four weeks following an Acelepryn application to kill the feeding larvae that may have survived and before damage is observable. Provaunt may be used in resistant populations, because it has a different mode of action from pyrethroids.

Forever ants

Ant control is difficult, says Swier, because ants are social insects. Within her colony, the queen is protected. While sprays can affect a large number of the queen’s daughters, control is only temporary, perhaps a couple of weeks. As the queen continues to produce new daughters, the colony again grows.

Baits are the key to ant control, says Swier, but how to deliver the bait without killing the messenger is the challenge. Worker ants will take bait to the queen, but the bait, containing a slow-acting insecticide, must not be effective while the worker daughter is carrying it.

One of the newer products to help control ants is Advion (active ingredient indoxacarb), a combination of a new, slower-acting class of chemistry and a bait. The product is registered for lawns, but requires a commercial applicators’ license.

As Swier sees it

Swier is enthusiastic about the turn the industry is taking toward reduced-risk products for turf and ornamentals. “We are entering a new era when turf products are becoming safer to use. With little sacrifice in convenience, they provide good control of pests. It’s a phenomenal time to be a researcher in the field,” he says.

Kathleen Hatt is a freelance writer and editor and a frequent contributor to Moose River Media. She lives in Henniker, N.H.