23 



between the fourth and fifth pairs of stigmata, a brownish organ, prob- 

 ably the anus, represented by two backward-directed pointed prongs, 

 with an oval opening in front of them. 



Adult female (fig. 7). — Length 4 11UU by 2 mm in diameter; color, when 

 living, bright orange; eyes minute and purplish-brown. The body is 

 elongated, elliptical, with both ends rounded; under side of the abdo- 

 men concave, its lateral margins re volute; the dorsum convex. All 

 the segments are well defined. The anal opening is simple, situated on 

 the under side of the abdomen, close to the concavity, and with diffi- 

 culty to be seen. The rostrum is wanting. Legs stout and rather 

 short; tarsi shorter than tibiae; the digitules simple. Antenna? stout 

 and nine-jointed ; the first joint is the longest and much the stoutest, 

 being nearly twice the diameter of the second joint; joint two is 

 slightly longer than the last one and cylindrical; joints three to eight 

 are subequal in length, of nearly the same 

 diameter and somewhat stoutest near the 

 apex, where they bear a fringe of fine hairs, 

 which grows gradually longer toward the 

 end of the antennas; the last joint is 

 rounded at the apex and bears three or 

 four fine hairs and the same number of 

 slender spines. The body is covered with 

 short and stiff brownish hairs, which 

 are stoutest and most dense at the end 

 of the abdomen. The pores are small and 

 scattered. The stigmatal tubes are sirn- 

 similar to those in the previous stages. 

 (See figs. 7, «, adult female and 1) an- 



tenna of same.) 

 Male. — The young larva? of this sex re- 



FlG. 7. — Xylococcus betulce: a, adult 

 female, seen from below, much en- 

 larged ; b, antenna of same more en- 

 larged (original). 



semble those of the female in every respect, 

 except that they are a little smaller. 



Male, second stage. — Length about 1.9 mm - by about l mm across the 

 thorax. Color quite dark orange. The thorax, as well as the abdomen, 

 is distinctly segmented; sides of the abdomen parallel, broadly 

 rounded behind; head and thorax combined about one- third longer 

 than the abdomen, the mesothorax being the largest. Antenna? seven- 

 jointed, short, stout, and moderately tapering; first joint longest and 

 stoutest, the second joint shortest; three to six subequal in length and 

 somewhat longer than the second, the seventh about as long as the two 

 preceding united, and bluntly rounded at tip; all bear long and fine 

 hairs about the apex, and the seventh, in addition, a number of stout 

 spines. Legs long and stout, the tarsi shorter than the tibia?, the digi- 

 tules fine and hair-like. There appear to be numerous hairs scattered 

 over the body, most dense around the end of the abdomen. 



Male, third stage. — In changing to this form the larva loses both the 



