18 



CIRCULAR 2 7 0, U. S. DEPARTMENT OF AGRICULTURE 



very dry and dusty appearance. This species passes the winter in 

 the adult stage in leaves and trash on the ground, and in mild winters 

 some individuals are able to survive on the trees in crevices of the 

 bark. In the spring the mites migrate into the trees, first attacking 

 the foliage nearest the ground and gradually extending their opera- 

 tions to cover the whole tree. The mites are usually greenish or yellow- 



ish while feeding, 

 often with two dark 

 spots on the body. 

 The eggs, which are 

 almost colorless, are 

 laid in the webbing. 

 The young are similar 

 to the adults in ap- 

 pearance, except that 

 they have six legs in- 

 stead of eight. They 

 develop from egg to 

 adult in a week or 10 

 days, and there are 

 several generations in 

 a year, which makes 

 it possible for the 

 mites to become ex- 

 ceedingly numerous 

 in one season. Late 

 in July or in August, 

 particularly if the in- 

 festation is severe 

 and the mites are 

 crowded, many of the 

 adults cease feeding, 

 become reddish or 

 orange, and migrate 

 to their hibernating 

 places. Since this 

 migration is down- 

 ward, many of them 

 collect around the calyx ends of apples, where they spin a great deal 

 of webbing which takes on the appearance of cellophane. This species 

 thrives on a variety of fruit trees and also occurs on a milkweed (Apocy- 

 num) which grows in the orchards, but it is especially injurious to apple. 

 The European red mite (Paratetranychus pilosus (C. and F.)) lays 

 bright red overwintering eggs on the twigs and branches of fruit 

 trees (fig. 18), and when these eggs are numerous they are very 

 noticeable as reddish patches on the bark. They are also found in 

 the calyx end of mature apples (fig. 19). These eggs hatch in April 

 just before the blossoms open. The mites feed on the foliage, usually 

 on the underside and spin very little webbing. They are more 

 easily seen than the Pacific mite, being velvety or brownish red, with 

 conspicuous, whitish, curved spines on the back. During the summer 

 the eggs are laid on the leaves, and there are seven or eight genera- 

 tions in a season. This species is very seldom found on anything 

 except deciduous fruit trees. 



Figure 19. — Overwintering eggs of the European red 

 mite in calyx end of apple. X 12. 



