Description: Though at first the spherical eggs of this mite are colorless and transparent, they become opaque as they age and become a greenish-yellow color as they near hatching. Both nymphal stages resemble the adult with the female being more oval than the male. Body color varies from yellow to pale green but is never reddish like the morphologically identical Tetranychus cinnabarinus. There is usually a dark spot on each side of the dorsal midline; hence the name.

Adult females overwinter and may turn an orange color in late fall. As the weather warms in the spring, the female will begin laying eggs. Parthenogenesis (reproduction without fertilization) is common. Newly hatched eggs give rise to the larvae which in turn give rise to two stages of nymphs. The adult follows the second nymphal stage. This whole process will normally take from 10 to 14 days during the summer with individual females living an average of two months. There can be 10 to 12 generations per year.

If mites are suspected, hold a sheet of white paper beneath a branch and tap the branch. Mites will be dislodged and can be seen as tiny specks on the paper that move about.

Mites primarily feed on lower leaf surfaces. Using their piercing mouthparts to stab epidermal cells, they withdraw the cellular contents which cause the cells to collapse. Chlorotic spots occur where damaged adjacent cells coalesce. A stippling appears on upper leaf surfaces. Severely damaged leaves may die.