1915 



ENTOMOLOGICAL SOCIETY 



103 



the offender. The reasons for these suspicions were: first, that the few unhatched 

 eggs were red, whereas the eggs of T. himaculatus are almost colorless ; second, there 

 was no visible fine web underneath the leaves as in the case of T. himaculatus; third, 

 the eggs were on both surfaces, being very common in the furrow of the midrib of 

 the upper surafce; and, fourth, all the eggs were attached directly to the surface of 

 the leaf. These last two characteristics are for the mos»t part contrary to the habits 

 of T. himaculatus. 



In 1913, having again found numerous trees affected in the same manner and 

 the mites causing the trouble present in large numbers, I sent specimens to Mr. 

 ISTathan Banks of the Bureau of Entomology, Washington, D.C., who at first thought 

 they were Tetranychus mytilaspidis, the Southern Eed Spider, which attacks citrus 

 trees, and which he supposed had escaped from the greenhouse. On sending further 

 material with some account of the wide territory over which the mite was being 

 found, together with its host plants, he answered as follows: " The red mite on, the 



Fig. 20. — Imported Red Spider. 

 (Tetranychus pilosus.) 



Fig. 21. — Common Red Spider. 

 ( Tetranychus himaculatus. ) 



plum is the European Tetranyclms pilosus, which occurs there on pears and other 

 fruit. Its relation to T. mytilaspidis is very close and perhaps identical, but the 

 latter species has been only known to us from the south and mostly on oranges." 

 He stated further that this was the first record of T. pilosus in America and asked 

 for more material and data, which were at once forwarded. 



Description of Appearance of Tetranychus Pilosus as Seen Under a Hand 



Lens. 



The mites are about the same size as T. himaculatus, but are stouter and more 

 nearly circular in outline of (body. Unlike T. himaculatus, the females are apparent- 

 ly always, even in the immature stages, red in colour. The mature females are dark 

 red, some being decidedly blackish, but the mouth parts and often a median dorsal 

 longitudinal area, especially on the posterior half of the body, are paler red. The 

 ventral surface is paler than tlie dorsal. The legs are whitish, tinged with red. On 

 the dorsal surface are a few small, whitish tubercles arranged in parallel rows. Four 

 longitudinal rows with three tubercles in each can easily be seen. There are, how- 

 ever, more tubercles but not easily made out with a hand lens. From each tubercle 



