stough: the hackberry psylla. 125 



Pachypsylla can properly be compared. In the convexity of 

 the body it greatly surpasses Psylla, from which it is at once 

 distinguished by the vertical and rugosepunctate head, the 

 quadrate vertex, the short frontal cones, the less filiform and 

 stout antennae." This species was first listed for Kansas by 

 Tucker in 1907. 



The coloration of Pachypsylla has been well described by 

 Riley. The general color is dark brown, with the abdomen 

 showing pinkish shades along the edges of each segment. The 

 wing pattern is dark brown, and the ocelli are red. 



This insect is quite short bodied ; the sexes are easily distin- 

 guished, as in all representatives of the family, the end of the 

 abdomen being pointed in the female but blunt and appendage- 

 bearing in the male. The total length of body averages, for the 

 male, 3.2 mm., and for the female, 3.6 mm. 



HEAD. 



The head is carried in such a position relative to the re- 

 mainder of the body that the epicranium is in an almost ver- 

 tical position (3J^-4)* the frontal cones pointing downward, 

 with the outer face of the frons in a horizontal position, its 

 distal end projecting caudad. Viewed from the front, the head 

 corresponds roughly, in general shape, to a right triangle, 

 truncate at the vertex, the posterior edge of the epicranium 

 lying on the base of this triangle, and a point somewhat be- 

 yond the frontal cones representing the vertex (28-4). The 

 whole head is rather flat, thin, rectangular, and boxlike, the 

 open side of the box being the caudal side (28-1), against and 

 into which opening fit the anterior part of the prostemum, the 

 procoxse and the mouth parts. 



The following parts and regions of the head, excluding the 

 frons and clypeus, which will be described under "mouth 

 parts," are to be found : epicranium, gense, frontal cones, an- 

 tennal sockets, compound eyes, and ocelli. 



The epicranium forms the front wall of the head and is ver- 

 tical in position. Its posterior margin is slightly concave, and 

 curves caudad and ventrad to the opposite side of the head, 

 forming a roll-like edge. This roll-like portion is the dorsal 

 part of the head when the latter is in normal position. This 

 region of the head (28-4, ep) is rectangular, about 0.45 mm. 



* Read plate XXXIV, fig. 4. 



