Friday, June 1, 2012

Insects pick up activity in late May

The last week of May was a busy time for insects. Many people reported seeing insects in corn and soybean. Brian Lang wins the prize for finding the first soybean aphid of 2012. I think he usually finds the first ones, even though the prize is just a "woo hoo" from me. Finding winged aphids and first instars is difficult on VC-V1 soybean, so I always try to look for ants and lady beetles.

Lady beetles, pirate bugs and lacewing larvae find soybean aphid on young soybean and are easier to see than aphids. Photo by Marlin E. Rice.

I saw my first Japanese beetle today near the ISU Library. A few adults were destroying a rose garden as the blooms were trying to open up. I also got a few calls this week about white grubs feeding on corn and soybean roots. We have several white grubs as possible culprits, including annual, true and Japanese beetles. Unfortunately, there are no rescue treatments for actively-feeding grubs in field crops.

 White grubs have three pairs of true legs and are always in a c-shape.  Photo by David Cappaert, Michigan State University.

Many people are sending me great photos showing caterpillar damage in corn. Black cutworm is still actively damaging late-planted corn in some areas, but older corn (>V5) should be big enough avoid clipping. First generation European corn borer and corn earworm larvae can be seen in a few fields. For some reason ECB females are attracted to taller corn, so check those fields first (especially if they are non-Bt hybrids). Various armyworms, cutworms and thistle caterpillar have also been reported at low densities in corn.

Corn earworm caterpillars vary greatly in color, ranging from light green to pink to brown. They have light and dark stripes running length of the body. Photo by Clemson University. 

For more insect activity updates, read this ICM News article. You may be seeing more insects out there and I would appreciate any pictures or reports you may have.

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