African cowpea thripsMegalurothrips sjostedti
The cowpea flower thrips or African bean flower thrips are shiny, black, slender, small-winged insects that feed on flower buds and flowers. During the pre-flowering period, nymphs and adults may damage the terminal buds. However, the main damage is on the flower buds and flowers. Attacked flower buds become brown and eventually fall off, leaving behind dark red scars. Damaged flowers are distorted and malformed. They change colour and may fall off early, with the result that pods are not formed. If pods do begin to form and become infested, they will be malformed.
The insect’s life cycle takes 14-18 days. Eggs are laid in flower buds and nymphs feed on the plant, causing extensive damage. Pupae develop in the soil. (Plantwise Knowledge Bank)