About one quarter the size of a ladybug, Delphastus is a small, shiny black beetle that feeds on several species of whitefly, including greenhouse, sweetpotato (silverleaf) and avocado whitefly. If whiteflies are not present, they will also feed on spider mites. Both the adult beetle and larvae eat whitefly eggs and larvae. Each container includes 25 live adults. Gardeners simply mail in the postcards or register online to have their insect orders shipped to their doors at no extra cost.