Spotted Bollworms belong to the species Earias vitella and E. insulana. They are part of the Noctuidae family and order Lepidoptera. They are known for causing damage to crops such as Cotton and bhendi. The main identifying feature of these insects is their green, dull-colored body with black longitudinal spots and tiny stout bristles. The spotted bollworm, Earias vittella, is a common pest in the southern regions of India.
The larvae of the spotted bollworm cause damage. In India, Earias insulana is found in the north, while Earias vitella is a prevalent pest in the south. Alternative host plants for the pest include Hibiscus, Holyhock, Sunhemp, China rose, bhendi, pundi, Abutilon indicum, and others.
Spotted Bollworms management in Cotton
The life cycle of Spotted Bollworms
- Moths: Pale with green features, approximately 2 cm long, can be found on flowers or close to light sources. Forewings are pale with bright green streaks, and hind-wings are silky-white suffused with pale brownish-grey.
- Eggs: Blue, laid singly on young shoots, leaves, and squares.
- Larvae: Light brown with grey to green and pale along the mid-dorsal line. Fully grown larvae are up to 1.8 cm long and covered in tiny spines visible under a hand lens.
- Pupation: Maturing larvae pupate in a silken cocoon attached to leaves or fallen plant parts.
- Generation Time: A generation is complete within 20-25 days under tropical conditions. Low temperatures can delay the process for up to two months.
Identification of the Spotted Bollworms
E. vitella and E. insulana are spotted bollworm species commonly found in cotton crops.
E. vitella Identification:
- Larva: The larva of E. vitella is brownish with white streaks along the mid-dorsal line and pale yellow ventrally. It does not have finger-shaped processes.
- Adult: The adult of E. vitella is small and buff-colored, with pea green forewings with a wedge-shaped white band running from the base to the outer margin.
E. insulana identification
- Larva: The larva of E. insulana is brown with a white median longitudinal streak on the dorsum. The last two thoracic segments and all the abdominal segments have two pairs of fleshy tubercles, one dorsal and the other lateral.
- Pupa: The pupa of E. insulana is brown and boat-shaped.
- Adult: The adult of E. insulana is small and buff-colored, with uniformly silvery green forewings.
Symptoms of damage by Spotted Bollworms
- Flare square, or flare-up, symptoms are common in cotton crops damaged by spotted bollworm.
- When bolls are attacked, larval feeding spoils the lint.
- Caterpillars that have just hatched burrow into the fragile shoots, causing the plant to wither, droop, and dry up.
- Caterpillars travel from the shoots and begin destroying the bolls by creating holes as the squares and bolls develop.
- The growing bolls have been harmed, and some may fall to the ground.