STATE HORTICULTURAL SOCIETY. 



195 



75. Pemphigus rhois, Fitch. The Sumac Gall Plant-louse. 



This species forms 

 tomato-shaped galls on 

 the leaves of different 

 kinds of sumac, which 

 usually arise from the 

 mid-vein at or near the 

 ^ base. The shell of these 

 J galls is very thin, and the 

 winged lice are found in- 

 side, in large numbers, in 

 September. The winged 

 individuals have the veins 

 of the wings arranged as 

 F'g- ^^- in the preceding, but they 



are much smaller, and the antennae are only four-jointed. 



76. Pemphigus uhni-fusus, Walsh. The Red Elm Gall-louse. 



This is a very minute species, which forms a solitary spindle-shaped 

 gall, about an inch long, upon the upper surface of the leaves of the red 

 elm. The winged individuals measure only about one-fourteenth (0.07) 

 of an inch to the tips of the wings, and are of a uniform dusky color. 

 An occasional specimen has the third vein partially or fully forked, as in 

 Eriosoma, thereby indicating a close relationship to that genus. 



77. Pemphigus populicaulis, Fitch. The Poplar-leaf Gall-louse. 



This species forms the 

 swellings or galls about the 

 size of a bullet, so often seen 

 on the leaves of the cotton- 

 wood {Populus monilifera) at 

 the point where the blade 

 joins the stalk or petiole. 

 These galls often assume a 

 reddish tint, and sometimes 

 grow to the size of a small 

 marble ; having a mouth-like 

 orifice on the under side and 

 a cavity within where the lice 

 reside. As Dr. LeBaron has 

 given an account of this spe- 

 cies in his Third Report, it is 

 unnecessary for me to notice 

 it further than to give a de- 

 scription of the species which is omitted in his report. 



Fig. 7. Pemphigus Populicaulis. 



a. Incipient gall on the under side of the leaf; b, Correspoiid- 

 in.« bulge on the upper side ; c. Fully formed gall : d , 

 Young galls ; /, Wingless female ; g. Winged insect. 



