You Are Here: Management Updates 2001 Archive June 25, 2001

Date: June 25, 2001
Category: Insects
Subject: Hyperodes Weevils

The ANNUAL BLUEGRASS WEEVIL has finished the first generation in the metropolitan New York area and samples collected from golf courses in that region are primarily yielding adults. These adults are beginning to mate and lay eggs for the second generation. On golf courses that have a history of heavy activity, superintendents should consider applying an insecticide this week or early next week (slightly ahead of our "usual" target date of July 4th). As a reminder, Merit* by itself is not particularly effective against annual bluegrass weevils. All of the pyrethroids that are labeled for use on golf courses appear to be quite effective when targeting adults.

However, you should be aware that we have seen a wide range of development this year. There is much more variability than we have ever seen. For example, samples taken from one golf course in central Connecticut almost two weeks ago yielded large larvae and pupae, while samples taken from another golf course less than five miles from the first revealed much smaller larvae. We have seen a one to two week difference in development on a single golf course.

So timing of insecticide applications is a bit challenging this year. Golf courses in the southern part of the New England range probably are nearing the end of the first generation and an application next week (2 - 6 July) should work well. Most golf courses in northern New England (i.e., Vermont, New Hampshire, or Maine) appear to be closer to "normal", whatever that is ... and are still seeing some larvae and pupae in the turf.

If you still see a significant number of pupae (the all-white, diamond-shaped stage) in the soil, you need to WAIT - those pupae are not susceptible to any of the chemicals we have available, and you need to wait until they emerge as adults. The plan then is to eliminate them before they have a chance to lay eggs. From here on through the rest of the growing season, timing of application will be a bit of a 'crap shoot', because there will be lots of overlap of generations. In other words, when you sample for the insect, you are likely to find small larvae, medium-sized larvae, large larvae, and pupae all at the same time.

- Submitted by: Dr. Pat Vittum