NDSU Extension Service - Williams County

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May 21, 2015

White Grubs

With the weather becoming nicer, homeowners are starting to work on their lawns and flower beds. With that being said, white grubs are starting to feed on the roots of your lawn as well. Detecting the presence of these insects might not happen until July when you see dead patches of lawn, which is easily pulled out of the ground.  According to NDSU Extension Entomologist Janet Knodel, the action threshold is three to four larvae per square foot in lawns. To detect the amount of white grubs found, simply dig up a section and look for white C-shaped larva approximately 1 inch long.

White grubs have a three year life cycle, the first year adults emerge from their wintering sites, 6-18 inches in the soil and fly to willow and poplar trees to feed and mate.  After the female lays the eggs, 30-50 days later, they will hatch and the larvae will feed on grass roots and organic matter, then moving further down into the soil to hibernate for the winter.

 The second year is the most damaging stage. They will feed all year long, laying no eggs. Once fall arrives they will move down into the soil to hibernate for the winter. The third year the insects are mature, they do limited feeding on grass roots The mature larvae will move down into the soil, go into a resting stage and are inactive, once spring comes again the life cycle will start over.

Systemic insecticides such as imidacloprid or halofenozide, provide effective control if applied approximately one month before the heaviest feeding times, soil applications should be made mid to late May. Neither of these will revived the dead lawn caused by the white grubs. Avoiding yard lights in your lawn or nearby will lower the amount of beetles that are attracted to those areas, helping to prevent egg laying.

Land Reclamation

On Tuesday June 2nd, there will be a free Land Reclamation meeting held at the Williston Research Center (14120 Highway 2). Specialists from NDSU coming to talk about the reclamation process, easements and agreements. There will be a panel of local landowners, and specialists for all questions and concerns. This event is being put on by the NDSU Extension Service, Williams County Soil Conservation and the NRCS. Pre-register by Thursday May 28th at 701-577-4595.

 

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