22 KANSAS UNIVERSITY SCIENCE BULLETIN. 



monilifera? ) similar to that formed by the other species, yet 

 differing in that the petiole seems to be twisted or folded so 

 that the gall is formed. It is from a fourth to three-fourths of 

 an inch in diameter, with a narrow transverse opening on one 

 side where the petiole overlaps, which allows the emigration of 

 the adult forms. 



Pemphigus populitransversus Riley. Plate IV, fig. 29. 



Head and antennae black. Length of segments : I, 0.09 mm.; 

 II, 0.09 ram. ; III, 0.02 mm. ; IV, 0.09 mm. ; V, 1.28 mm. ; 

 VI, with unguis 1.64 mm. ; unguis alone, 0.03 mm. ; total 

 length, 0.74 mm., extending to the insertion of the fore wings. 

 Sensoria transverse and broad, but not completely encircling 

 the joints of the third and fourth segments. Three or four 

 sensoria on the third segment, also a characteristic spur at the 

 inner lateral border of the first sensorium. Two sensoria on the 

 fourth, a large circular patch containing three or four small 

 circular sensoria, which have ten or twelve small papillary 

 hairs on their surfaces. One large sensory patch on the sixth 

 near the unguis, which has in it two or three small circular 

 sensoria containing hairs similar to those of the fifth sensorium. 

 Unguis is armoured with about six small, sharp bristles at its 

 distal end. Eyes black, ocular tubercles prominent, ocelli three, 

 and not very conspicuous. Beak dark, 0.27 ram. long, extend- 

 ing a little beyond the first coxa. 



Prothorax sraoky ; thorax black and arched. Wings hyaline, 

 with a brownish venation. Stigma uniform in color, 0.72 ram. 

 long by 0.20 rara. wide. Total wing expansion, 6.64 ram. Legs 

 black, slightly hirsute. 



Abdoraen sraoky yellow. Honey-tubes and style absent. 

 Total length of body, 2.72 rara. 



This form was taken the 8th of October, on the Cottonwood 

 {Populus vionilifera) . It is gregarious in habit, living in a gall 

 in the distal end of the petiole. This gall is from one- to three- 

 fourths of an inch in diaraeter. It has a sraall transverse open- 

 ing near and parallel to the base of the leaf, through which the 

 adults eraerge. In these colonies of frora a hundred to four 

 hundred is one and soraetiraes two stera-mothers. These are 

 apterous and reproduce viviparously at the rate of about ten 

 per day. In these galls are nuraerous globules of liquid which 



