Spider Mites On Ornamentals
Spider mites are extremely small but can cause much damage.
On most mites overwinter as eggs which hatch in the spring. An exception is the honeylocust spider mite that overwinters as an adult female. All overwintering stages are found in protected places on the host. In the spring the eggs hatch or are laid.
The immature mites go through several stages before becoming adult. There can be several generations per year allowing the build up of large populations.
The injury becomes most obvious first on older foliage. Infested foliage has a speckled appearance and appears to be losing its green coloration.
Heavy mite infestations will form fine webbing. The honeylocust spider mite will cause the foliage to turn yellow as though it were fall.
Spider mite detection is difficult. Foliage suspected to be infested can be examined with a microscope. Holding a white piece of paper under a branch suspected to be infested and shaking the branch may dislodge mites. The mites will appear as moving specks on the paper.
Pesticides labeled for mites include dormant oil, rotenone, Diazinon or malathion.