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Scouting Watch

July 3, 2002

It is time to spray for bagworms. Enough time has elapsed since they hatched that ballooning to new hosts should have ended. Bacillus thuringiensis kurstaki (Dipel, Thuricide), cyfluthrin (Tempo) and other pyrethroids, as well as other insecticides, are effective against these small larvae. As the larvae get older, cyfluthrin and the other pyrethroids will be most effective.

Fall webworms have hatched into the first generation in southern and central Illinois. There is only one generation of this insect in north-central and northern Illinois, occurring in August and September. This insect is not particularly damaging to tree health, but it is an obvious aesthetic pest. Hand removal of the large silk tents, along with their enclosed larvae, on the ends of branches is effective. If insecticide sprays are used, be sure to use enough pressure to break up and penetrate the silk tent.

Earwigs are very numerous at this time in Illinois. These 5/8-inch-long, elongate, brown insects with pincerlike forceps on the rear end hide during the day in protected areas. When found under the bark of a dying tree, they are commonly blamed for causing the tree to die, but they are just using the site as a place to hide. Those that find their way indoors should be removed by hand; they will eventually die indoors without reproducing. They have varied food habits, feeding on decaying plant material, leaves and flower petals of some plants, and other insects, including fleas. Their damage to the petals and leaves of rose, lily, zinnia, dahlia, aegeratum, and other flowers may justify control. Carbaryl (Sevin), rotenone, and other labeled insecticides applied to the foliage provides control. Do not spray the blooms, to avoid killing bees and other beneficial pollinating insects.

Author: Phil Nixon


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