Issue 1, April 16, 2012

Scouting Watch

Eastern tent caterpillar is more numerous in southeastern Illinois that I ever remember seeing before. It is common to see 15-foot tall trees with a dozen or so large silk tents. Although this insect can strip trees when very numerous, the trees will typically re-leaf with few, if any, obvious effects. This insect attacks tree members of the rose family including crabapple, flowering cherry, purple-leaf plum, hawthorn, and serviceberry. Bacillus thuringiensis kurstaki (Dipel, Thuricide) is the insecticide of choice as it does not affect bees and other pollinators coming to the blossoms.

European pine sawfly, Eastern tent caterpillar, and Gypsy moth have been present throughout the state since late March. Remember that although European pine sawfly larvae look similar to caterpillars, they are the larvae of wasp-like insects and are not controlled by Btk.

Scouting to verify insect presence and susceptibility is even more important this year with the early spring. In early springs, most insects will emerge early but some may appear later than expected given the warm weather. Some insects require a lengthy warm-up period to break diapause which is supplied during a typical spring. Others rely more on day-length to break dormancy. Our recent period of very warm weather will have caused most insects to speed up development, but some may still be behind phenological and degree day indicators. Don’t initiate insect control actions using only these data, scout to verify insect presence and susceptibility. (Phil Nixon)

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