HICKORY. LIMBS HICKORY-GALL APHIS 155 



protrude three short thread-like processes, of which the outer ones are slightly 

 longer. The feet are long, slender, and tinged more or less with brownish 

 towards their tips. The single spur at the tip of each of the shanks is of a pale 

 yellow color. The wings arc transparent and glassy but not clear, the surface 

 being minutely granular as usual in this genus and strongly iridescent. Their 

 veins are honey-yellow and have a waxj r appearance; those which traverse the 

 posterior portion of the wings are hyaline and colorless, and become abortive at 

 their tips in the margin. 



The females differ from the males in being of a much larger size, measuring 

 almost half an inch to the tips of the wings, which, when spread, arc three- 

 fourths of an inch across. The head approaches to a square form, and is broad- 

 er than the thorax; the upper jaws are more robust, and of a dark reddish 

 brown color; both the head and thorax are minutely punctured and pubescent; 

 the abdomen is proportionally larger and less narrowed towards each extremi- 

 ty, is but six-jointed, and has no projecting processes at its tip, the scale on 

 the peduncle at its base is very slightly and sometimes not at all notched, and 

 the two transverse rows of short bristles on each segment are much more dis- 

 tinct; the feet and sometimes the shanks are of a dark reddish brown color; 

 and in the wings the vein which bounds the inner side of the cubital cell arises 

 outside of the middle of the transverse medial vein, instead of in the middle, 

 which is the point where it originates in the males. Some females are met 

 with which have gnawed off their wings and cast them away, this being a com- 

 mon habit among ants of this sex. These wingless females may be distinguished 

 from the largest sized workers by being of a still larger size, and the cicatrices 

 of the cast off wings are very obvious on the sides of the thorax. 



The neuters or workers are always destitute of wings, and are generally 

 smaller than the males, varying in length from 0.20 to 0.33. In all other re- 

 spects they resemble the females, except that they have no ocelli and a very 

 narrow thorax plainly divided into three segments by impressed sutures. The 

 scale of the abdominal pedicel is almost circular, being a little higher than it is 

 wide, and is regulaly rounded above, without being cut off as in the female, or 

 notched as in the male; it is convex on both sides, but with a slight concavity 

 in the middle of its posterior face. 



The following varieties may be found among these ants : 



a. Female. Scale of the abdominal pedicel not at all notched. 



6. Female. Middle transverse sutures of the abdomen strongly constricted. 



c. Female. Middle sutures of the abdomen pale, forming a transverse band. 



d. Neuter. Basal suture of the abdomen pale yellowish brown. 



e. Neuter. Two basal sutures of the abdomen pale yellowish brown. 



/. Neuter. Antennae and legs dark reddish brown, instead of black. These 

 are probably young individuals, recently hatched. 



Upon the twigs and leaf-stalks hollow green bullet-like galls of a leathery 

 texture, their inner surface covered with minute white and yellow 

 lice; the gall afterwards turning black, opening and becoming cup- 

 shaped. 



The Hickory-gall Aphis. Pemphigus Carymcaulis. 



A disease of the young limbs of the hickory, which will remind 

 one of the well known black knots upon the cherry, is of such 



