|Two-spotted spider mite, photo courtesy Iowa State University|
Spider mites are oval shaped; yellowish or greenish in color. They’re difficult to see clearly with the naked eye, measuring only 1/50th of an inch. Magnification can reveal amber-colored mite eggs, whitish cast skins, and black fecal specks. To verify spider mite presence, place a sheet of white paper under discolored leaves. Tap the leaves, then watch for tiny moving creatures on the paper.
Spider mites thrive in dry, warm conditions. They make their way indoors in summer and sometimes as hidden guests on Christmas trees and greenery in December.
Mites first feed on the undersides of leaves, then expand their territory as populations increase, moving from stem to stem and onto nearby plants by means of fine webbing. People can also spread them accidentally on their hands, clothing, and watering cans. Always wash your hands and any tools you’ve used after working with infested plants.
|Spider mite webs, photo courtesy UMN Extension|
Control options: Keep plants well watered to reduce their susceptibility to spider mites. You can take a hose and spray infested leaves and needles to dislodge some of the spider mites. If you want to treat your plants, consider applying insecticidal soap or horticultural oil. Although they are only moderately effective against mites, they are 'soft' on natural enemies and helps preserve any predators or parasites that are present. The product must directly contact the mites to kill them and repeated treatments may be necessary.