PERGANDE — NORTH AMERICAN PHYLLOXERINiE. 245 



The size of the galls varies from 5-25"™- in diameter. Those 

 growing singly often attain immense proportions, but when 

 nu iierous or crowded they are reduced in size and often conflu- 

 ent, so as to form an elongated mass. Before maturity of the 

 inhabitants the gall is closed, but as soon as any of the inmates 

 have acquired wings, it cracks transversely into 3-6 or more 

 broad and more or less irregular bracts so as to allow the mature 

 migrants to escape, and to leave room and food for the younger 

 individuals. The color is pale yellowish-green, more or less 

 tinted with red or crimson. The walls of the galls are rather 

 thick and succulent when young, becoming more tough and 

 leathery when older and hard, brown or black when empty and 

 dry. 



Stem-mothkr. — I^ength when fully grown 0.8-1. 8™™- and 

 about 0.6-1. 2™™- in diameter ; often almost globular. The color 

 varies, according to age, from greenish-yellow to brownish-yellow, 

 with a faint dusky shade. Eyes dark purple ; antennas and legs 

 blackish. Two transverse, more or less distinct frontal fovese, 

 dusky. The whole surface of the body is quite densely covered 

 with extremely minute, sharp points, most dense, and arranged 

 in rows, on the abdominal segments. Antennae rather short, the 

 third joint of about uniform diameter, scarcely twice the length 

 of the two basal joints combined and divided by about 8-13 more 

 or less distinct and coarse annulations ; the thumb small, though 

 quite distinct and apparently movable. 



Egg. — Elongate-ovoid, colorless or faintly greenish, polished 

 and translucent. 



lyARVA. — Either colorless or faintly yellowish, or yellowish- 

 green, with the eyes red. Surface of body profusely covered with 

 minute tubercle, each provided with a short hair. 



Pupa. — The youngest pupae are pale greenish-yellow and the 

 older ones pale orange, with the antennae, legs and external edge 

 of wing-cases dusky. Eyes and ocellar spots reddish. 



Migratory female. — I^ength of body 1.2-1.8"°"-. Expanse 

 of wings 3 . 4-3 . 8™"- . Color paler or darker orange ; the prothorax 

 darkest, marked more or less distinctly with either two transverse 

 spots or a continuous line near anterior margin, a transvere, 

 medio-dorsal, more or less curved spot, often divided at middle, a 



[Proc. D. a. S., Vol. IX.] 30 LNov. 23, 1903.] 



