Biology of cabbage butterfly, Pieris brassicae (L.) on cabbage in Jorhat, Assam

Adults of Pieris brassicae (L.) were collected, reared and maintained in wooden rearing cages (90 × 60 cm) on cabbage leaves in laboratory at 26°C, 85% relative humidity (RH) and 14:10 L:D. Five larval instars were observed. The results of morphometric measurement revealed that the average length and breadth of egg, first, second, third, fourth and fifth instar larvae were 1.12 ± 0.04, 4.25 ± 0.95, 8.06 ± 0.79, 15.10 ± 0.88, 25.54 ± 0.97, 36.50 ± 0.98 mm and 0.54 ± 0.06, 0.37 ± 0.02, 1.65 ± 0.19, 3.28 ± 0.25, 4.18 ± 0.36, 4.82 ± 0.47 mm, respectively. The average length and breadth of pupa were 25.28 ± 0.96 and 6.34 ± 0.82 mm, respectively whereas the length and wing expansion of male and female butterflies were 19.2 ± 0.98 mm and 52.96 ± 1.00 and 23.16 ± 0.99 mm and 62.92 ± 1.01 mm, respectively.