e course

Pests of Cotton :: Major Pests :: Spotted bollworms

1. Spotted bollworms: Earias vitella & E. insulana (Noctuidae: Lepidoptera)

Distribution and status: Cosmopolitan. Major pest

Host range: Cotton, bhendi, holly hock, Hibiscus cannabinus, Abutilon indicum

Damage symptoms: In the beginning of the season, when the crop is a few weeks old, the small caterpillar on hatching out from the egg leads a free life for a few hours. Then it bores into top tender shoot, the portion of the shoot above the damage withers, droops and dries up. Depending upon the locality upto 50 per cent of the crop may be damaged in this manner. When the squares and bolls begin to develop, these caterpillars move from the shoots and start damaging bolls by making conspicuous holes into them. The squares and small bolls injured by the larvae drop away from the plants. The developing bolls are also damaged and some of the damaged bolls fall to the ground. The infested bolls, which are not shed, are destroyed by the larvae eating the seeds and filling them with excrement. Such affected bolls may open prematurely and badly. 

Cotton Bollworms (Video)


Bionomics: Earias vittella has green forewigns with white streak in each of them. Earias insulana has complete green forewings Scuptured, crown shaped, deep sky blue colour eggs are deposited singly on the shoot tips, buds, flowers, fruits. Egg period is 3 days Larva is brown with dorsum showing a white median longitudinal streak; the last two thoracic segments and all the abdominal segments have two pairs of fleshy tubercles (finger shaped processes), one dorsal and the other lateral. E. vittella is without finger shaped processes. Larval period is 10-12 days. Pupation is outside the bolls in a tough, boat shaped, dirty white silken cocoon. Pupal period is 7-10 days.