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Northern Illinois Agriculture

University of Illinois Extension
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Will this warm weather increase the liklihood of insect problems?

Posted by Russel Higgins -

I saw a butterfly yesterday! I cannot remember the exact date when I normally notice butterfly's in a year, but March 16th seemed earlier than normal. A question received often in recent weeks is for a prediction of insect pest populations, especially in light of Illinois's mild winter. Dr. Mike Gray, University of Illinois Extension Entomologist was posed this question at a gathering in Champaign this past week. Dr. Gray shared several observations
  • Insect pests were at very low levels going into the winter months. Insect pest surveys resulted in such low numbers for most of Illinois Dr. Gray suggested the term of "insect pest deserts"
  • Most of the major insect pest in corn and soybean production overwinter as eggs, larval or pupal stages and are very successful at surviving Illinois winters whether warm or cold.
  • Saturated soils at insect hatch or early larval stages probably has a greater influence on soil inhabiting insect mortality than weather events through the winter.

2012 should not be considered a problematic year based on our immediate winter temperatures alone. However, we  should point out that predicting upcoming growing seasons insect issues in March is an inexact science at best.  We do know that temperature is a major driving factor for insects in completing life cycles. This fact can be verified by watching your porch light and seeing the large populations already swarming. With our recent weather we have accumulated measurable insect heat units which encourage our insects pests that overwinter as adults (Alfalfa weevil, Bean leaf beetles) to become active and start feeding. Our insects that need to finish instars or pupate could be expected to show up earlier or much earlier this year, depending upon future weather patterns.

What is the take home message? Don't panic because of the relatively warm winter, but do not ignore insects either. Consider scouting for insect pests earlier than normal in 2012.

This question is one that must be a concern to farmers across the corn belt. General insect pest survival was addressed in the Purdue newsletter and Bean leaf beetle survivability was addressed in the Iowa State newsletter.

For more information visit their respective sites


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