You Are Here: Management Updates 2008 Archive July 14, 2008

Date: July 14, 2008
Category: Insects
Subject: White Grubs, Annual Bluegrass (Hyperodes) Weevil

Beetles in flight
As most of you have already noticed, the beetles of most of the annual white grubs are flying actively now. The oriental beetles started showing up in significant numbers about two weeks ago, and the Japanese beetles appeared right on schedule, during the week of July 4th. The European chafers have been flying for two or three weeks in most locations in southern New England, and the asiatic garden beetles have been "out and about" for a couple weeks as well.

The earliest emerging beetles may be laying eggs already, especially in areas where soil moistures are good. Oviposition (egg-laying) will begin in most areas of southern New England within the next week or two - earlier for European chafers, slightly later for Japanese beetles.

For areas that have a history of grub activity from past years, you have several options. There are three neonicotinoids on the market which have historically provided good control of European chafers, oriental beetles, and Japanese beetles. They include imidacloprid (Merit™ and other trade names), thiamethoxam (Meridian™), and chlothianidin (Arena™). In addition there are two combination products that have one of the neonicotinoids and a pyrethroid. These are Allectus™ (Merit™ plus Talstar™) and Aloft™ (Arena™ plus a generic form of bifenthrin). Any of these products should do an excellent job of controlling white grubs if applied between now (mid July) and the first week of August. Later applications may also work, but the neonicotinoids are known to be very effective when applied during the time beetles are laying eggs.

In addition, a new product from DuPont has been very effective against grubs. Chlorantraniliprole, sold as Acelepryn™, was registered by the EPA in April 2008, and five of the six New England states quickly followed with the necessary state registrations. So those of you in Connecticut, Maine, New Hampshire, Rhode Island, and Vermont have the option of using Acelepryn™ now to control white grubs. We will let you know as soon as the product receives registration in Massachusetts.

Annual bluegrass weevils
Briefly, it looks like this will be yet another confusing and frustrating summer. Based on reports from superintendents throughout southern New England, it appears that you were seeing large larvae, pupae, and adults in some areas last week, but also saw small larvae in other areas. All I can suggest at this point is to remain vigilant with your monitoring. If most of the individuals you see are adults, try a product that has activity against adults (usually a pyrethroid or chlorpyrifos). If most of the insects are larvae, try using trichlorfon (Dylox™) or indoxacarb (Provaunt™). If they are mostly pupae, wait a week and then use an adult-active product.

I am guessing that the rains that fell in many regions have been masking the damage. So if you have not already done so, get out and take a close look at your annual bluegrass. My fervent hope is that you do not find the larvae in there, thumbing their little noses at you!

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.

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