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John Fulton

John Fulton
Former County Extension Director

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In The Backyard

Horticulture columns and tips done on a timely basis
Identifying white grubs


Posted by John Fulton -

It has definitely been another unusual year weather wise. Of course I could really make a case for there really not being a "usual" weather pattern anymore, but rather an average of extremes. We are probably running a good two weeks behind normal in development and temperature.

We do have the first May/June beetles out for the year. These insects come from grubs in the lawn or garden. This brings us to the first frequently asked question of the week: "When do I treat for grubs?" To start with, there are several types of grubs. There are several types of grubs. There are the annual white grubs, true white grubs, Japanese beetle grubs, and green June bug grubs. There are others, and these are called by many names as well, but this will suffice for the discussion today.

All these beetles have a larvae called a grub, and have a complete life cycle. The cycle goes egg, larvae, pupa, and adult. I mentioned seeing the first adults of the season of the May beetle. I also found several Japanese beetle larvae while planting some flowers. The larvae of the Japanese beetles will be with us for a few more weeks before they pupate. Then of course the actual beetle stage follows the pupa. What this really means is we are in a rotten time to try and treat the larvae (grub) stage. The May beetles will have all the eggs hatched out by the end of July, and the Japanese beetle larvae will be around the third or fourth week of August.

The old timing (before the Japanese beetle) for grub control was around the Logan County Fair. This allowed all the eggs to hatch out into grubs before the treatment was applied. The grubs were also small at the time, and smaller grubs are easier to control than the large ones. Now with the Japanese beetles covering most of the county, it is recommended to treat around the end of August to allow all those eggs to hatch.

Many products say they can be applied in the spring to control grubs all season, and they will when they first come on the market. Over time, microbes that break the chemicals down build up in population. When this happens, the products can no longer provide long periods of control. History is full of cases of insecticides no longer being effective because of microbial degradation. I'll cover the products available for application when the correct application timing draws near.

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