Press-Republican

April 29, 2013

Grubs are making a comeback

By AMY IVY, Cornell Cooperative Extension
Press-Republican

---- — Homeowners around Plattsburgh, Morrisonville, Beekmantown and beyond have been battling white grubs in their lawns for years now. 

The damage is twofold. Grubs kill turf by devouring the roots so that large chunks of turf can be pulled up like a carpet. And then each spring, skunks, raccoons and crows tear up infested turf in search of those tasty grubs.  

The calls to our office about grubs peaked in the early 2000s, and for the last few years the number of grub questions has tapered off. We still get questions, but not so many. But this spring we have had many more calls than usual. I don’t know the reason, but they seem to be making a comeback.

The good news is that there is a new product on the market that is very effective and yet is extremely low in toxicity to vertebrates like us and our pets. And according to Dr. Patricia Vittum, entomologist at the University of Massachusetts, this product has no activity against bees. 

The common name of this product is chlorantraniliprole. I know that’s a mouthful; I’m still trying to master its pronunciation and spelling. It’s important to know the common name so you can be sure you’re getting the right product. It’s available to homeowners this year under the brand name GrubEx. 

Choosing the right product can be challenging because there are so many options on the shelf. The key is to look for the active ingredient; every package has to list this in a box on the label, usually on the front. GrubEx used to contain imidacloprid as the active ingredient, but now it has chlorantraniliprole.

TIMING

The timing of the application is important and varies with the active ingredient. The most effective way to control grubs is to target the newly hatched grubs while they are still small, usually in August to early September. 

But chlorantraniliprole takes 60 to 90 days to become effective, so the best time to apply this product is from late April through early June, in a single application.

This is a little different from the timing for imidacloprid, the other choice for homeowners. Applying this product too soon is a waste, since you’ll have to reapply it. The best time to make your single application of imidacloprid is in June or July. New research is showing it can be applied into August as well.

There is a third product on the shelves with the active ingredient trichlorfon, sold as 24 Hour Grub Control. This is much more toxic than the other two options and kills grubs for only a 24-hour window of time. If you choose this product, wait until you find young grubs in your lawn in late summer, and make the application then. If grubs are not present, it will be a waste.

None of these products is effective on the large grubs you are finding right now. Those are the older larvae from last year’s hatch, and they are just about to pupate and become adult beetles. At this late stage, they are very resistant to insecticides. You are better off reseeding bare areas in your lawn now and treating with the less-toxic products to control the next generation as it hatches out in late summer.

Grubs are a complicated problem. For a free, updated fact sheet about white grubs and your control options, contact our office at 561-7450 or email Jolene Wallace at jmw442@cornell.edu.

PESTICIDE DISCLAIMER: Every effort has been made to provide correct, complete and up-to-date pesticide recommendations. Nevertheless, changes in pesticide regulations occur constantly, and human errors are still possible. These recommendations are not a substitute for pesticide labeling. Please read the label before applying any pesticide, and follow the directions exactly.

Amy Ivy is executive director of Cornell Cooperative Extension, Clinton County. Office phone numbers: Clinton County, 561-7450; Essex County, 962-4810; Franklin County, 483-7403. Website: www.cce.cornell.edu/ecgardening. Email questions to askMG@cornell.edu.