PERGANDE — NORTH AMERICAN PHYLLOXERINjE. 241 



galls, were finally discovered snugly hid away either in deep 

 cracks of the bark or at the bottom of deep and more or less com- 

 pletely closed depressions, which are found on the trunk and 

 stouter twigs and which are caused by the decay and dropping 

 out of small branchlets. Here the insects live upon the juices 

 from the tender bark which forms at the bottom of the cavities. 

 These colonies usually consist of the stem-mother, a number of 

 fully grown apterous females and larvae (both the direct pro- 

 geny of the stem-mother) and eggs of three different sizes. The 

 smallest, and most numerous of these eggs, correspond exactly 

 in size and general appearance with those deposited by the stem- 

 mother in the galls, while the others are about twice as large but 

 yet of two sizes, the larger ones of a regularly ovoid shape, the 

 smaller more conoidal in outline. The former produce, after a 

 few days, the true sexual female, and the latter the male, which 

 pair, when the female brings forth her single impregnated or 

 winter egg which doubtless hibernates within the cavity. 



In some of the depressions no stem-mother is found, but only 

 the other forms here described and a few of the winter eggs. 



Stem-mother. — Ivength of body 0.8-1. 2""'-. Shape broadly 

 ovoid, or almost globular. General color pale yellowish, growing 

 gradually darker while increasing in age. Antennae, legs and 

 rostrum pale dusky. Eyes, blood-red, composed of three ocelli 

 each side, arranged triangularly on a conical prominence. 

 Antennae with the first joint stoutest and. about as long as wide; 

 the second somewhat more elongate, stoutest at anterior end; 

 both together somewhat shorter that the third; joint 3 slender 

 and tapering slightly toward both ends and divided by 5-8 more 

 or less distinct serrations ; the thumb minute and movable ; tip 

 blunt and provided with three fine and short hairs. Surface of 

 body covered with minute granulations, and ornamented in addi- 

 tion with six rows of small and somewhat conical, and slightly 

 dusky tubercles ; five similar tubercles each side of the head pro- 

 vided with a minute hair. Head short, almost twice as broad as 

 long and more or less distinctly separated from the body. 



Egg FROM STEM-MOTHER.— Ivength 0.2"'"-, and about o.i"""- 

 in diameter. Ovoid, highly polished and apparently without a 

 trace of sculpture. White, or with but the faintest yellow tinge. 



