You Are Here: Management Updates 2003 Archive September 18, 2003

Date: September 18, 2003
Category: Insects
Subject: Chinchbugs, White Grubs, Call for Grubs

Chinchbugs
I received a report from a lawn care professional in response to an earlier posting. He pointed out that many lawns in western Massachusetts have in fact been heavily impacted by chinchbugs this season. He reported they have treated more lawns for chinchbugs this year than in most recent years, and that most lawns received a Merit™ application in July. This would suggest that Merit™ is not "suppressing" chinchbugs, at least not this year.

White Grubs
We just returned from digging white grubs in Berkshire County. We found European chafers in a site that had been entirely Japanese beetles for the past 15 years. That in itself is not surprising since European chafers have been very well established in many parts of western Berkshire County (most notably Pittsfield and Great Barrington) for many years. The chafers were mostly third instars, although some were just in the process of molting to that largest stage. We also saw some Japanese beetles, mostly in the second instar.

Turf managers are asking about how late they can use Dylox™ as a curative ("clean-up") treatment. We really don't know, but many folks used Dylox fairly late last autumn and reported good success. Personally I suspect the product will continue to work reasonably well as long as the soil temperature is above 60 F but once the temperatures begin to drop, I believe the effectiveness of the material will drop too. One of the chemical representatives commented that turf managers are still applying Dylox™ on Long Island this late in the season with excellent results. Of course our soils are a little cooler, so the answer is a bit less clear.

Note that a late season application of Dylox™ is not going to provide complete control, but it often reduces grub populations 60 to 80%. That may be enough to bring a raging population under threshold levels.

In any case, consider this a "heads up". The areas where we were seeing 30 to 40 grubs per square foot this morning looked fine on the surface, but there was little or no root system underneath. Because soil moistures have remained good this autumn, the root damage has been masked - but once skunks or raccoons get a good sniff, they are likely to cause devastation as they rummage for those tasty morsels. And keep in mind that European chafers are absolutely the toughest species to deal with, in part because they are less sensitive to cold. That means they will continue to feed through November and into December in many locations, and will even resume feeding in March as the snow is melting.

Call for Grubs
Finally, a colleague of mine (Albrecht Koppenhofer, at Rutgers University) is in search of about 1,500 European chafer grubs. If anyone knows of a site where he could collect large numbers of grubs in a reasonably short period of time, please contact me (pvittum@ent.umass.edu, 413-545-0268). Thanks!!

- Submitted by: Dr. Pat Vittum