You Are Here: Management Updates 2005 Archive June 24, 2005

Date: June 24, 2005
Category: Insects
Subject: Annual Bluegrass (Hyperodes) Weevil, White Grubs, Webworms

Hyperodes weevils - things are popping now!
We collected samples from Westchester County earlier this week and found 35% large larvae, 25% pupae, and 35% adults. The population is just finishing the first generation and most feeding should be over, at least at that site. But keep in mind that every site is different, and there may be a few days difference from one part of a golf course to another. Golf courses in much of New England are a few days behind Westchester County, so new adults may just be appearing at some of those locations.

For superintendents who find a similar breakdown (35:25:35), I would recommend treating the most heavily infested areas near the end of next week with something that stays in the thatch (a pyrethroid or chlorpyrifos often work well). Remember that some pyrethroids are sensitive to high temperatures, so you may want to wait until the current hot spell breaks. Superintendents further north are still seeing mostly larvae. If damage is excessive and most of the insects are still in the larval stage, you may get some relief with trichlorfon.

The rest of the season will be a "by guess and by golly" kind of year, I think. It appears that the egg-laying period was much longer this spring, so all the stages are more spread out than usual. And there will be even more "spreading out" with each successive generation so eventually you will find every stage at any given time. Keep monitoring and base your insecticide decisions on what is there, both in numbers and in stage of development. (For the spring the tolerance level is often between 30 and 80 larvae per square foot, while it is considerably lower in summer months.)

White grubs
While sampling for Hyperodes weevils this week, we found two brand new beetle adults. One was an oriental beetle (which was still white when my lab assistant found it), and the other was a Japanese beetle. Again these were in Westchester County, New York, which is a bit warmer than most of New England. But it serves notice that these beetles probably will be emerging right about on schedule this summer, in spite of the cool and wet conditions we experienced through much of the spring. So be watching the Japanese beetles (day time fliers) and assume the oriental beetles (mostly night fliers) will be out and about at the same time.

Webworms
While I was mowing my own lawn last night, I noticed several webworm moths flitting about. I admit I did not successfully catch any of them. (One of the prices of getting older is that I am not as quick as I used to be). But I just mention their presence. Very seldom do webworms cause visible damage on home lawn settings, but some clients certainly will want to know what is going on. In most species the female moths drop eggs indiscriminantly as they fly. Some eggs land over turf and trickle down into the thatch, where they hatch into caterpillars that feed in the thatch. Many of the eggs will land on pavement and die, and many caterpillars will become dinner for birds. So just because you see webworm moths flying, it does not necessarily mean you will experience damage to the turf.

Stay cool.

Submitted by: Dr. Pat Vittum

DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The author and the University of Massachusetts are not liable for any consequences of any pesticide "recommendations". Mention of any trade name is not to be considered endorsement of a product.

Links followed by the symbol are external links that open in a new window.