Sonya Broughton, Department of Agriculture & Food Western Australia, Bugwood.org

It’s a record-breaking 100 degrees F today in the Washington DC Metro Area- and so far, a pretty dry June. These conditions are favorable for the TWO SPOTTED SPIDER MITE to proliferate in the landscape. The two-spotted spider mite, Tetranychus urticae, is a pest of landscapes and greenhouses. Plants attacked by two-spotted spider mites include: roses, Euonymus, dogwood, pear, butterfly bush, marigolds, cannas, viburnum, chrysanthum and many others.

Spider mites inject their mouthparts into plant cells and suck out cell contents, which causes a flecking or stippled appearance to the plant. Heavy infestations build webs, decrease plant vigor, and can cause premature leaf drop. Two-spotted spider mites feed on the underside of the leaves and are yellowish green with a spot on either side. Females lay an average of about 140 eggs when temperatures exceed 80°F and a generation can be completed in a week.

Sample for spider mites by shaking plant material over a white sheet of paper on a clipboard. Mites will appear as rapidly moving dots and will smear when smashed. Sample at least every other week during the summer. Look for stippling on leaves or webbing, which is found on heavily infested plants.

Temporarily knock off the mites and provide relief to water-stressed plants by spraying plants with a strong stream of water. Predatory mites and other predators feed on two-spotted spider mites, but they may have difficulty keeping populations low under ideal mite conditions.  Pesticides are poisonous and some can even cause increases in the mite.