Biology of Gesonia gemma (Swinhoe) on soybean

Studies on the biology of grey semilooper, Gesonia gemma were carried out in the laboratory during the rainy season of 2012. A female laid eggs from 149 to 247 (average 182 ± 36.97) on the upper surface of the soybean (Glycine max L.) leaves. Most of the eggs were deposited near midrib and basal part of the leaves. There were 5 larval instars, differing in colouration. Fully grown larvae measured 18.0-22.0 mm in length and 2.0-2.5 mm in width. Prolegs were present on 4th, 5th, 6th and last abdominal segment. The duration of the egg, larval and pupal periods was 2-3, 9-17 and 7-8 days, respectively. The total duration from egg to adult emergence was completed in 18-28 days. The size of the pupa was 8-9 mm in length and 1.9 to 2.1 mm in width. Female pupa was comparatively long in size than male. Medium sized moth measuring 6.0-8.0 mm body length 15.0-17.0 mm wing expanse. The longevity of adult male and female was 3 to 6 and 2 to 8 days, respectively.