You Are Here: Management Updates 2001 Archive August 22, 2001

Date: August 22, 2001
Category: Insects
Subject: Hyperodes Weevils, White Grubs, Chinch Bugs

We have had several reports (and have seen for ourselves) of ANNUAL BLUEGRASS WEEVILS (HYPERODES WEEVILS) feeding on golf courses throughout Connecticut. Damage appears to be sporadic, but those who are experiencing the infestations are losing some turf. In most cases the activity is on fairways or collars. Unfortunately, the timing of the larval outburst could not have been worse - feeding began during that beastly hot weather two weeks ago, and has continued. Golf courses in Massachusetts and points north should be seeing similar activity now.

Because there is so much overlap (all stages present at the same time), it has been difficult to figure out what to do. In general, if monitoring reveals areas where at least 50% of the population in the turf is still in the larval stage (white with brown head), it may pay to apply a quick-acting material that moves through the thatch, such as Dylox, to get limited relief. Dylox probably will control no more than 50% of the larvae that are present at the time, and will not have any impact on pupae or adults, but for some situations, that will be enough to allow the turf to begin to recover. NOTE that annual bluegrass weevils are NOT on the Dylox label, so the applicator makes such an application at his or her own risk. Also note that some states prohibit applications when the pest is not on the label, while others only require that the site (in this case, golf course) is specified. (The above paragraph is NOT a formal recommendation and should not be taken as an endorsement of the product.)

Some superintendents have applied a synthetic pyrethroid in an effort to control the larvae after they begin to feed. Reports of success vary - some insist that the materials work well, while others have not felt there was any control at all. Our limited field trials suggest that the pyrethroids probably are not as effective targeting large larvae as they are when applied earlier, targeting adults and very small larvae.

As always, if more than 50% of the population is already in the pupa stage (cream colored, diamond-shaped, with no brown head), it is already too late to do anything. None of the turf insecticides will have any impact on the pupae, so save your time and your money... and pray for rain.

My guess is that some new adults that emerge (during the next two or three weeks, depending on location) will lay eggs, attempting to start yet another generation. However, any larvae that emerge from that egg-laying should not be active until in mid September, and are unlikely to cause any visible damage. Very few larvae survive the winter (in fact, this spring was the first time in 25 years that we observed any larvae that had survived the winter), so the worst should be over very soon.

On another front, WHITE GRUBS are active now. We were monitoring a golf course in the Berkshires yesterday and found several second instar Japanese beetle grubs in fairways and roughs. While we have not been sampling personally in the eastern part of the state, it is safe to assume that European chafers are developing on schedule. Keep in mind that European chafers tend to prefer dry areas, so turf expanses that are looking parched following the recent hot weather may be harboring chafer grubs, while the locations that were blessed with well-timed rain throughout the summer (yes, there are a FEW of those!) may not be hit quite as hard this year, at least with chafers. The flip side is that Japanese beetles love the lush green sites - so you can count on one or the other!

Remember to check the areas that appear to be drought-stricken. CHINCH BUGS are active in many locations and may be responsible for at least some of that brown turf!

And finally, things seem to be pretty quiet on the ARMYWORM front. We are still trying to figure out some of the details (like, where did they come from? where have they gone? will we see them again next year?), but I guess this is an example of "Silence is golden."

- Submitted by: Dr. Pat Vittum