No abstract

The comparative biological studies on yellow stem borer, Scirpophaga incertulas (Wlk.) and white Stem Borer, Scirpophaga fusciflua Hampson showed that the moths of both species preferred to lay eggs on the dorsal surface of leaves. The eggs were laid in masses during night hours and covered with brownish hairs of the anal tuft. The maximum eggs of S. incertulas hatched on 6th day, whereas the S. fusciflua eggs hatched on the 5th day with per cent hatchability of 86 and 93 per cent, respectively. There were six larval instars in S. incertulas with 25-34 days larval duration and five for S. fusciflua with 26-31 days larval duration. The pupal period lasts for 7-9 days in both species, and the adults emerge from the pupae during dusk hours. Adults exhibited sexual dimorphism. The longevity of male and female moths was also similar in both species. The morphometries of larval head capsule width were more in S. incertulas as compared to S. fusciflua. Male pupal weight of both the species were almost similar but it was varied significantly in female pupa S. incertulas (0.024mg) and S. fusciflua (0.032mg).