McDaniel spider mite
Tetranychus mcdanieli
The McDaniel spider mite overwinters as an orange-colored diapausing female under bark scales or in litter at the base of the tree. Overwintering mites, which are often in large masses, produce extensive webbing. The mites emerge from their overwintering sites in March or April, depending on the area, but at about the time fruit buds begin to open. They move to the green tissue and begin to feed. Mites may move directly into the tree fruit host or, if available, to nearby weed hosts. As they feed, they lose their orange color and take on the normal greenish tinge and characteristic dorsal spots. After a few days of feeding, egg laying begins.
Life stages
Immatures: The larva has three pairs of legs and is about the same size as the egg. It has little or no color until it begins feeding when it takes on a greenish tinge from leaf chlorophyll. The quiescent stage is about 1/12 inch (0.20 mm) long. The protonymph is oval and dark green and has four pairs of legs. The female is 1/100 inch (0.25 mm) long, and the males are slightly smaller. The deutonymph also has four pairs of legs and is generally the same color and shape as the preceding stage, only larger. The female, which is about 1/70 inch (0.35mm) long, can readily be distinguished from the male at this stage. The male has characteristic slender, tapered abdomen and is distinctly smaller than the female.
Adults: The adult female is about 1/60 inch (0.44 mm) long, whereas the male is only about 1/80 inch (0.29) long.The adult female, like the deutonymphs, can also be distinguished from the male by its shape. The female has a broad oval shape, whereas the male has a slender, more pointed abdomen. The dark spots on the abdomen that characterize this species occur on all stages but are most distinctive in the older stages. The earlier stages may be difficult to distinguish from twospotted spider mite because of the variability in both species. McDaniel spider mite has multiple pairs of spots, some of which always occur in the posterior portion of the abdomen.
Twospotted spider mite, on the other hand, usually has two fairly distinct spots, and the area of pigmentation is confined to the front half of the abdomen. Both species lose their spots during a molt and do not regain them until they begin feeding again. Because of the variability, identification may be difficult. However, slide mounting and examination under high magnification make it possible to distinguish the two species.