WILLOW MITES. 595 
92. Aspidiotus convexus Corastock. 
THE CONVEX WILLOW SCALE. 
The following account is copied from Professor Coinstock T s report in 
U. S. Agricultural Eeport for 1880: 
This species, which is very common 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. Buta careful study of 
the structure of the two forms show them to be specifically distinct. The most 
striking differences 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. Described 
from seven females, two males, and very many scales. 
93. Phytoptus salicicola Garman. 
Order Acarixa. 
Produces galls on the leaves of the long-leaved willow, Salix longifolia Muhl. 
Striae 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 longitudiual 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 iu the margin of a shallow pool of water in the 
vicinity of formal, 111., was badly infested by the galls. (Garman). 
94. Phytoptus sp. 
Produces galls on the leaves of the heart-leaved willow, Salix cordaia Muhl. 
The mite has sixty-three transverse abdominal striae. 
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 
