Biology, nature and extent of damage of Lymantria marginata Walker and Orthaga eudrusalis, serious pests of mango have been studied from 1983 to 1985. L. marginata damage occurred in an epidemic form in August-September 1983 and damaged upto 90 per cent leaves in orchards of Rampur, Moradabad, Meerut, Bijnor, Muzaffarnagar and Sabaranpur districts is U P. Moths of this species showed sexual dimorphism.
Female has white fore wings with black patches, wing span 52 mm, body length 22 mm and antennae pectinate 7 mm long.
While males have fore wings of dull grey colour, wing span 41 mm, body colour grey, body length 15 mm, eggs laid in cluster of 10 to 50 on trunk, twigs and ground, were oval and brownish red.
Egg, larval and pupal period ranged from 7–15, 25–56 and 8–25 days, respectively.
Pest has three main generations in a year.
Mature larvae were grey coloured and 4.5 cm in length.
These pupated on trunk, branches and in fallen leaves.
O. eudrusalis female moths have grey coloured fore wings with patches of shining scales (wing span 31 mm). Mature caterpillers measured 25 mm in length pale greyish with two white stripes on dorsum.
These webbed the leaves together and feed inside.
Egg, larval and pupal period varied from 4–7, 25–33 and 8–45 days respectively.
Larvae hibernated from December to March in tough waterproof cocoons in ground.