You Are Here: Management Updates 2005 Archive September 16, 2005

Date: September 16, 2005
Category: Insects
Subject: Wireworms

Several of our faithful readers have reported an unusual situation - they are seeing wireworms in turf settings and seeing damage as a result of these insects. Wireworms normally are not a major problem in turf but apparently something about this summer has been to their liking.

Wireworms are the larvae of click beetles. Wireworms are quite slender, often yellow to brown, and relatively hard-bodied and somewhat flattened. They range in size from 0.25 to 1.5 inches. They can be found in many different kinds of soil, and may be present at any time of year. We often see a few wireworms when we are digging for grubs but have never associated them with damage. The adults are "click beetles" - somewhat elongated beetles that have a special structure on the underside that enables the beetle to flip up in the air, ostensibly away from harm. The beetle makes a clicking noise when engaging this "spring". Most click beetles are about 0.5 inch long.

Wireworms/click beetles have a long life cycle. The larvae (wireworms) may be present for two to six years at a given location. When they complete their development, they pupate (also in the soil) for about two weeks in late summer before the new adults emerge. The insects overwinter as adults, which then lay eggs the following spring. Most wireworms feed on seeds or occasionally on roots of grasses or grassy crops. They also will bore into fleshy underground stems.

The bad news is that the agricultural producers who deal with wireworms report them as being very difficult to manage. The wireworms are in the soil and have a very heavily sclerotized exoskeleton, which gives them an extra level of protection against insecticides. Most of the soil insecticides that might have been effective have been removed from the turf market. (As an aside, there are those who think the old organochlorines, like DDT, chlordane, and dieldrin, provided years of protection and we didn't even know it.) Vegetable producers recommended planting a different crop the following year, one that the wireworms won't like. Obviously we can't do that in turf!

So for now we have no tangible suggestions. Manage the damage as much as possible - raise the mowing height if possible to give the roots a chance to develop more deeply and withstand attack. The rains passing through today may provide some relief. I am not aware of any turf insecticides that are currently available and labeled for wireworm, but will look into it.

A wireworm larva		A wireworm adult
Photos courtesy of University of Illinois Extension

Submitted by: Dr. Pat Vittum

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