Author : Pensook Ratisoontorn

Summary : The biology of C. suppressalis and the response of four larval instars to five insecticides were investigated. The study was made in laboratory from May 1970 to May 1971. The total developmental period of C. suppressalis on rice (Rexoro variety) from egg laying to adult emergence was 42 to 59 days for the female and 39 to 54 days for the male with an average of 48.6 and 43.7 days, respectively. The incubation period lasted from 5 to 7 days with an average of 5.3 days. There were 6 larval instars. The first and second instars ranged from 3 to 5 days with an average of 3.6 and 3.5 days, respectively. The third instar lasted from 4 to 5 days with an average of 4.3 days for female and 4.1 days for the male. The fourth instar ranged from 4 to 6 days with an average of 4.7 and 4.3 days for female and male repectively. The fifth instar ranged from 4 to 7 days with an average of 6.0 for female and 5.2 days for the male. The sixth instar lasted for 8 to 19 days, the average for the female was 14.4 days and 11.0 days for the male. The total larval period lasted from 31 to 43 days for female and 28 to 38 days for the male, with an average of 36.4 and 31.5 days, respectively. The pupal period ranged from 6 to 9 days with an average of 7.0 days for female and 6.9 days for the male. A female can lay from 20 to 202 eggs with an average of 118.6.