Spotted Bollworm

Identifiable traits

These larvae mainly attack bolls, but also feed on squares, shoots and flowers if bolls are not present. If infested during the vegetative state, the caterpillars feed through the terminal buds of the shoots and move downward. This causes drying and shedding of terminal shoots before flowering. If the main stem is affected, the larvae will feed on flower buds and bolls, entering through holes bored around the base. Damaged flower buds sometimes spread prematurely, resulting in so-called ‘flared squares’. The damage to plant tissue and presence of excrement lead to colonization by fungal or bacterial infections, worsening the symptoms. The younger the plant is when it is attacked, the more damage this pest can cause. Alternative host plants for this pest are, among others, hibiscus and okra.

Inducing factors

Damage is caused by the larvae of the spotted bollworm, Earias vittella, a common pest in the southern regions of India.  The moths are mostly pale with green features, approximately 2 cm long and can be found on flowers or close to light sources. The forewings are pale with bright green streaks, the hind-wings are silky-white suffused with pale brownish-grey. Eggs are blue in color and laid singly on young shoots, leaves and squares. The young larvae is light brown with grey to green features, and pale along the mid dorsal line, fully grown larvae are up to 1.8 cm long. Tiny spines, visible under a hand lens, cover most of the body surface. As they reach maturity, they pupate in a silken cocoon attached to larvae or fallen plant parts. Under tropic conditions, a generation is complete within 20-25 days. Low temperatures can delay the process for up to two months.