All development usually occurs on the underside of the leaf. High populations of spider mites can develop quickly during hot, dry conditions. Webbing is usually visible during moderate to heavy infestations. The webbing can cover foliage and flowers, and detract from a plant's appearance. Heavy populations can severely defoliate and kill plants.
Mites penetrate leaf surfaces with their sharp, slender mouthparts and remove cell contents.
Injured leaf tissues have no chloroplasts and appear chlorotic and stippled. Spider mites also may inject toxins or growth-regulating chemicals into the plant which can result in leaf desiccation and defoliation. Some predatory mites also are available and have been shown to be effective. However, in some greenhouses, the heavy use of pesticides prevents the effective use of natural enemies. The above insects and mites are examples of some of the pests that you may encounter in the greenhouse.