You Are Here: Management Updates 2004 Archive June 29, 2004

Date: June 29, 2004
Category: Insects
Subject: Annual Bluegrass (Hyperodes) Weevil, White Grubs, Caterpillars

As the U.S. Women's Open gets underway this week at The Orchards, in South Hadley, it is time to send out an insect update. (Pardon the "commercial" but western Massachusetts is very proud to be hosting this prestigious event.)

Annual bluegrass weevils
Many golf course superintendents throughout the Northeast experienced a challenging spring, with heavy infestations of the annual bluegrass weevil. Telephone calls here have slowed down a bit. Based on the samples we have been collecting regularly from Westchester County, NY, and the brief respite from phone calls, I think much of New England is "between" generations. That is, there may be many adults present and active on the fairways, tees, and greens, but the eggs they are producing for the second generation are just beginning to hatch. So those of you from Massachusetts north should start looking for damage from the second generation any time in the next couple weeks.

For those of you in the metropolitan area and points south of there, the "overlap" has already begun. We looked at samples taken with a two inch corer last week, and found a small larva, a medium larva, a large larva, and a pupa, all in the same tiny plug! Some of you may already be seeing the telltale symptoms of heavy populations from the second generation.

From here through the rest of the summer, the trick is to determine which stage is the most predominant one at any given time. If you see mostly medium larvae and a few large larvae, you may have success knocking the populations down with a fast-acting product that does not get bound in the thatch. Note that some of those materials, such as Dylox™, are not labeled for use against annual bluegrass weevils. If you see mostly pupae, you are advised to delay any action for at least one week. This provides time for the pupae to develop to adults. (Remember that pupae are not vulnerable to any insecticides.) If you see mostly adults, particularly as they roam around on the surface of the fairways or greens, consider using a material that does bind in the thatch. Normally Dursban™ or a pyrethroid would be a good choice. In each case, water in the application lightly.

White grubs
We have had a few reports of Japanese beetle adults flying, particularly in areas around New York City. We normally expect to see adults around July 4th here in Amherst, and I suspect they will be pretty close to "on time" this summer. So far the white grub development is expected to be very close to "normal" this summer. One factor that could change that would be an extended dry period. If we do experience a stretch of several weeks without measurable rainfall, we can expect female beetles to delay egg laying until soil moisture conditions improve.

The good news for the short term is that grub activity that plagued some of you throughout the spring is over in most places. Most of the grubs that have not already pupated have stopped feeding.

Caterpillars
Dave Shetlar (Ohio State) mentioned in a recent e-mail newsletter that he had seen large numbers of armyworm moths in central Ohio. This is the first report I have had of armyworm activity this year. It is way too early to panic in New England. The moths that have been reported in Ohio may or may not make their way to New England. But it would be appropriate to keep your eyes especially tuned to possible armyworm activity. Remember that armyworm caterpillars are often nocturnal but when the caterpillars reach outbreak populations, they are also active in the day. Armyworm caterpillars are a very dark base color (often described as black or navy blue), have a two-toned brown head capsule that looks "honey-combed", and have a black splotch at the base of each fleshy leg (proleg) on the abdomen.

- Submitted by: Dr. Pat Vittum