You Are Here: Management Updates 2002 Archive June 21, 2002

Date: June 21, 2002
Category: Insects
Subject: Things are Popping

Lots of insect activity is being reported now that we have had some life-giving rain and the temperatures are warming up.

Annual Bluegrass Weevils (Hyperodes Weevils)
We are seeing damage from annual bluegrass weevil (ABW) larvae in many parts of southern New England. This year has been unusual because normally the adults emerge at about the same time in any given location (usually in April) and begin to lay eggs. This year I think some of the adults started moving during the warm weather in mid April (when temperatures approached 90 degrees in many locations) while others held back. When the temperatures dropped suddenly and remained cool for several weeks, those adults were left "holding the bag" , or in this case, holding the eggs. As a result, we had a very extended period of egg-laying, beginning with the warm weather in April and continuing well into May. This means that now, as we look at damage, we are finding small larvae, medium-sized larvae, large larvae, and pupae, all in the same two-inch diameter plug! It also means that it will be even harder than usual to predict weevil activity for the remainder of the summer.

In general I would suggest that those who think they need to treat for the second generation consider doing so two or three weeks AFTER they see the damage from the larvae. This allows the insects time to complete their larvael development, pupate, and emerge as adults. For much of Massachusetts, I think new adults will be emerging in the first week of July, so as usual you will need to schedule an application around the Fourth of July! Oh, Joy!!!

Dursban (chlorpyrifos) remains an option for ABW control on golf courses. Note that the application rate has been reduced to one pound AI per acre, but the DOW representatives have pointed out that the label does not limit the number of applications. You might consider making two applications (I don't believe one pound will be sufficient, although we do not have summer data on that rate), one or two days apart. As always, the synthetic pyrethroids are a good option as well. Water the application lightly (one or two passes of the sprinkler head), just enough to wash the material off the blades.

Some superintendents and suppliers have been asking about what they see as "failures" of Merit (imidacloprid) to control ABW larvae. Our field trials over the years have documented, pretty convincingly, that Merit by itself does NOT control ABW larvae. A tank mix of Merit with a synthetic pyrethroid can be very effective, but when you tease out the details, it is obvious that most of the mortality can be attributed to the pyrethroid in the tank mix. So I don't see these reports as "failures" of Merit, but rather the result of unreasonable expectations.

White Grubs
European chafer adults are beginning to fly - watch for them at sunset, especially in trees silhouetted against the western sky. They can show up literally in the thousands in particularly "favorite" trees. Other grub species are beginning to pupate, and we should start seeing a few Japanese beetle adults flying (daytime fliers) during the coming week.

European chafers may start to lay eggs as early as the first or second week of July. Other species normally lay eggs about two weeks later (if the soil moisture is suitable). Turf managers who are in areas with European chafer populations (much of the state east of Worcester and pockets in the Connecticut River Valley and Berkshire county, as well as mid coast Maine and southeastern New Hampshire) can apply Merit (imidacloprid) now, but be sure to water it in. If you are dealing with Japanese beetles rather than European chafers, delay the application a week or two if possible.

If we have dry conditions during much of July and August, we can expect European chafer activity to continue to spread throughout New England. (This species is generally favored by dry conditions.) At the same time, dry conditions force Japanese beetles and some other species to delay egg-laying until soil moistures improve. It's way too early to tell!

Chinch Bugs
Even though we had some heavy chinch bug infestations in some locations last summer (favored by the hot and dry conditions), I suspect the cool wet conditions in late winter and the lack of snow cover worked to the disadvantage of the insect. So right now I would predict that chinch bug activity would be no worse than normal this summer. However, if we revert to drought-like conditions for July and August, we will have to go back on chinch bug alert.

- Submitted by: Dr. Pat Vittum