The Pear Tkee Psilla. 251 



sum and venter are blackish, or brownisili black. Tlie dorsum of 

 the thorax and the cephalic half of the abdomen are marked on 

 each side the light meson by sixteen blackish spots; the tw.enty- 

 six on the thorax are of var;ylng sizes and shapes; tke six on the 

 abdomen are narrow elongate. On the venter of the abdomen, 

 eig'ht and sometimes ten similar spots occur, two large oval ones 

 on each side near the lateral edge, and two or three elongate ones 

 farther cephalad on each, side near the meson. The eyes are large 

 and of a crimson color. The legs are sUghtly darker than the body. 

 Oftentimes the ligh,t body color between the black is strongly 

 suffused with crimson. Stout hair or bristles project from the 

 following situations: Pour from the front of the head; the basal 

 and teiininal joints of the antennae each bear two; each leg has 

 several; three project from the cosital margin of each, front wing 

 pad, and two from the outer margin of each hind wing-pad; and 

 the caudal half of the abdomen is fringed with eight lai'ge and 

 fourteen smaller bristles. The encircling row of wax-cells about 

 the anus has a definite form which may be of specific importance. 



Figures 1 and 2, page 233, drawn with, a camera lucida, show 

 the position of the anus with its encircling rtug (Fig. 2, a) ; also the 

 situation, relative size, and foi'm of the biistles and blackish mark- 

 ings of the nymph. 



Summer form of adult, Psylla pyricola pyricola: Length 

 of body 2.25 mm.; the wings extend a little beyond the 

 eud of the abdomen. In general form they strikingly resem- 

 ble a Cicada in minature, the head is broad and held nearly 

 vertical; the thorax is strongly built, and the pronotum, all fouc 

 sclerites of the mesothorax, and the scutum and scutellum of the 

 metathorax are distinct on the dorsum; the abdomen is cyclind- 

 rical ovate, largest near the fourth segment and tapering to the 

 genital organs. The general color varies from a light scarlet to 

 crimson with black markings. Head (Fig. 7, a) broadly triangu- 

 lar, slightly concave caudad; the hair line just above the head! 

 in the figure represents the natural width, including the eyes; 

 the clypeus projects ventrad in the foim of two separate diverg-* 

 ing hairy cones (Fig. 7, c) with white tips and brownish redi 

 bases; the mesal suture of the epicranium is black with a lighteij 



