WILLOW MITES. 595 



92. Asjndiotiis convexus Comstock. 



THE CONVEX WILLOW SCALE. 



The following accouut is copied from Professor Comstock's report in 

 U. S. Agricultural Report for 1880: 



This species, wliich is very commoa on the bark of the trunk and limbs of the 

 native willows in California, very closely resembles Aspidiotus rapax in the shape 

 and color of its scale. The resemblance of the two species is so great that at first I 

 considered them identical, and concluded that A. rapax had spread to the cultivated 

 trees in California from the native willows of that State. But a careful study of 

 the structure of the two forms show them to be specifically distinct, The most 

 striking ditferences are those presented by the last abdominal segment of the female. 

 In this species there are four groups of spinnerets ; the superior laterals consisting 

 of about seven, and the inferior laterals of about four. In A. rapax the groups of 

 spinnerets are wanting. 



In this species the plates are very much shorter than in A. rapax, and very closely 

 resemble the plates in A. ancylus. But A. convexus differs greatly from A. ancylus in 

 the shape and color of the scale and in the wings of the male being long. Describyd 

 from seven females, two males, and very many scales. 



93. Phytoptus salicicola Garman. 



Order Acakina. 



Produces galls on the leaves of the long-leaved willow, Salix longifolia Muhl. 

 Strife of abdomen 46. Feather-like tarsal appendage with three pairs of prongs. 

 Length, .0075 inch. Abundant in the galls in June. 



This gall is one of the most remarkable deformations I have seen. 

 It consists of a narrow longitudinal upward fold extending sometimes 

 the entire length of the leaf. Usually there are two of these folds 

 on each leaf, one on each side of the midrib. They may be close to the 

 midrib, midway between it and the margin, or at the margin itself. In 

 cases where the fold begins next the midrib at the base of the leaf, it 

 may gradually leave it so as eventually to form a mere fold of the mar- 

 gin. The opening is a narrow slit running along the under side of the 

 leaf. Color, as seen in the latter part of June, brown. My attention 

 was drawn to this gall by the peculiar appearance of the willow leaves 

 due to the lessening of their widths by the fold. A clump of shrubby 

 willows growing in the margin of a shallow pool of water in the 

 vicinity of Kormal, 111., was badly infested by the galls. (Garman). 



94. Phytoptus sp. 



Produces galls on the leaves of the heart-leaved willow, Salix eordaia Muhl. 



The mite has sixty-three transverse abdominal strife. 



The gall is a wart-like excrescence sometimes projecting above the 

 leaf, sometimes below, and again equally above and below. In some 

 examples the leaf is folded up around the gall, forming a more or less 

 complete rim. Many of the galls are produced above into nipple- 

 shaped prominences. The color may be purple or pale green. A 



