Oviposition behaviour of the cotton bollworm, Heliothis armigera, and its relation to day-night cycle was examined under laboratory conditions. Eggs were laid both in large quantities of clumped eggs at one place, and singly distributed in the oviposition cage, always glued on the substrate. The maximum individual life time fecundity recorded was 3080, and the highest number of eggs delivered in 1 day was 949. The mean pre-oviposition period was 2.9 days. Peak fecundity occurred between days 5–9 and the highest mating frequency from days 4–6 after emergence. Maximum age for egg laying was 29 days, average life expectancy was 22 days, with longest individual survival of 32 days. Male longevity did not vary from that of females. There was a significant difference in the longevity of mated and virgin females; the mated females lived for a shorter time but produced a significantly higher number of eggs. Also, mating induced a sudden surge in oviposition. Almost 90% of the total eggs were laid in the darkness. Out of them, 60% were from the first and 30% from the second half of the dark period.
