Morphological characteristics of tetranychus viennensis: (1) Adult mites: Female adult mites are ovoid, about 0.5 mm long and 0.3 mm wide, with wide front, slightly raised back, slender back bristles, no obvious trichomes at the base, and 4 pairs of feet, divided into summer type and winter type. In summer, it is red at the beginning of molting and turns dark red after feeding. Scarlet and shiny in winter. Male mites are small, tapering at both ends, about 0.45 mm in length and 0.25 mm in width. At the initial stage of molting, they are light yellow, gradually turning green, and at the later stage, they are light yellow, with black and green fur markings on both sides of their backs.

(2) Eggs: spherical, yellow-white or orange.

(3) Juvenile mites: round at first, yellow and white, oval after feeding, light green. Three feet. If the terry is round, light green or light orange, dark green stripes appear on both sides of the back, and bristles begin to appear on the back. Four feet.