Corn Earworm Oviposition and the Effect of DDT on the Egg Predator Complex in Corn Silk1

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Abstract
During the growing season of 1959, observations were made on five plantings of sweet corn to determine some of the oviposition habits of the moth and to study the effect predators have on the mortality of eggs of the corn earworm (Heliothis zea (Boddie)). The plantings were made on May 15, May 25, June 4, June 14 and June 24. Earworm oviposition was relatively light in the first three plantings. In the last two plantings egg deposition increased considerably. This increase in activity is usually observed to occur late in the corn-growing season. Newly emerged silks were most attractive to the moths but even after silks were 10 days old, moths were observed to oviposit on them. The main predators responsible for egg mortality were Orius insidiosus (Say), Coleomegilla maculata (DeGeer) and Chrysopa oculata Say. Geocoris punctipes (Say), Nabis ferus (L.) and syrphid larvae were also observed in the silks but in very limited numbers, The effects of treatment with DDT-oil emulsion sprays on predator populations and egg mortality were also observed. Where spraying reduced the number of predators, mortality of earworm eggs was decreased.

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