Studies on biology and morphometric of Rice case-worm, Nymphula depunctalis Guenee

The results showed that the newly laid eggs were pale yellow, spherical and the average incubation period was 3.7±0.15 days. The total larval period consisted of five instars and covered 18.7±0.37 days. The duration of their developmental stages of first instar to fifth instar, pre-pupa and pupa were recorded as 2.8±0.13, 3.0±0.2, 3.6±0.16, 4.1±0.28, 4.9±0.18, 1.6±0.16 and 7.3±0.15 days, respectively. Since the second instar onwards, the larvae had constructed their cases and feed inside it. Further, the length and width of egg, first instar to fifth instar larva and pupa were measured as an average of 0.75±0.01, 2.23±0.05, 5.12±0.09, 8.11±0.10, 9.07±0.07, 11.87±0.15 and 5.95±0.05 mm and 0.51±0.0, 0.18±0.0, 0.35±0.0, 0.61±0.01, 0.84±0.01, 1.18±0.01 and 1.41±0.03 mm, respectively. Fecundity was found to be 114.8±16.38 eggs/female with pre-oviposition, oviposition and postoviposition days were found to be 1.3±0.15, 2.1±0.23 and 1.7±0.15 days, respectively. The total life span of N. depunctalis male and female completed within 32.8±0.55 and 35.6±0.81 days, respectively. The sex ratio of male to female was recorded as 1: 1.3.