Seasonal Abundance of Insect Pests of Soybeans

Abstract

Ground cloth samples of insect pests were taken weekly from 3 soybean fields during 1972 and 1973. Population levels of green cloverworm, Plathypena scabra (F.), were highest during late August in 1972 and early August in 1973. In 1972, larvae numbers of Heliothis larvae were present in late August but were not present in any of the fields in 1973. Populations of soybean looper, Pseudoplusia includens (Walker), and cabbage looper, Trichoplusia ni (Hübner), peaked during early September and also were present in low numbers during October. In 1973, velvetbean caterpillar, Anticarsia gemmatalis Hübner, occurred later than any other Lepidoptera (mid to late September). In 1972, they were virtually absent from all fields. Larvae of the Mexican bean beetle, Epilachna varivestis Mulsant, were abundant in mid-September and numbers of adults were increasing when sampling was terminated in mid-October. Populations of green cloverworms, soybean and cabbage loopers, Heliothis spp., and Mexican bean beetle larvae were present during the pod-set stage of the soybean plant and therefore should receive the most emphasis in developing insect management strategies.