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The P&PDL Picture of the Week

Japanese Beetles

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Japanese Beetle Grubs

Japanese Beetle Grubs
Japanese Beetle Adults

Japanese Beetle Adults

(Photo courtesy Department of Entomology, Purdue University)

We are expecting adult beetles very early this year and would likely have been in the middle of them already had we not experienced below normal temperatures the past few weeks. We have many in the pupal stages right now just waiting to pop out when temperatures rise. (We actually had our first emergence of an adult in the Lafayette area last week - our earliest record ever).

The real potential problem that we are seeing right now is that many 2nd instar grubs entered the winter last Fall. They are not as developed as they should be and may require several more weeks of feeding yet this spring. This means that they will come out as adults much later than normal this summer. SO ..... what we have is a year where the beetles will likely come out earlier but may also remain out longer in the season - extending the window of beetle activity. Not good news for those looking to control them. We do not yet have real good readings on how intense the population will be this year - however, in general, the wetter the spring, the higher the beetle mortality tends to be.

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Last updated: 8 June 2001/tlm.
The Plant & Pest Diagnostic Laboratory at Purdue University.