58 



quite slender, seven -jointed; in some specimens they reach just a little beyond the 

 tip of the wingpads; joint 3 slightly shorter than 7, joints 4 and 5 almost equal in 

 length; prothorax as broad as head and much narrower than next segment, its sides 

 almost parallel ; rest of body broadly oval and closely reticulated ; the thorax is 

 often marked each side with a rather indistinct darker subdorsal line, ending at the 

 posterior margin in quite distinct dusky or greenish spots or lines on the abdo- 

 men, which gradually increase in transverse length, being longest between the nec- 

 taries; two others beyond them connect with the lateral margin; nectaries about 

 as long as the third antennal joint, rather stouter at base, and reaching almost to 

 end of body. 



Mature or migratory form.— Length, 2.2 to 2.4 mm. ; expanse, 6.8 to 7 mm.; color, 

 greenish-yellow or yellowish-green ; the sides of the thorax generally more yellowish ; 

 head and prothorax dusky; antenme, thoracic lobes, sternal plates, apical third or 

 more of femora, apex of tibial, and three lateral abdominal spots black ; the abdo- 

 men is marked anteriorly with one or two narrow, more or less obliterated or inter- 

 rupted, transverse lines; a large, squarish, dusky spot, throwing out two short 

 branches each side, just in front of nectaries, covering segments 3 to 5, and a broad 

 band behind nectaries, connecting with their base; anal spot black; front of head 

 conical, frontal tubercles more or less distinctly gibbous, though never prolonged 

 and porrected as in Ph. Immuli; antennae slender, longer than the body, the third 

 joint yellowish at base, slightly shorter than the seventh and sparsely tuberculated ; 

 the fourth about as long as the two following ones together; legs long and slender, 

 especially the posterior tibia?, which are almost as long as the whole body; wings 

 large, their subcosta yellowish or greenish, stigma dusky, veins black; nectaries pale 

 dusky, darkest toward the end, long and slender, almost of equal diameter, being 

 rather slenderer a short distance above base, whence they bend inward, curving 

 gently outward beyond the middle; tail pale dusky, elongate, conical, nearly two- 

 thirds the length of nectaries, curved upward, furnished each side with three or 

 four rather long, slender, backward-curved hairs; its surface covered with numerous 

 transverse rows of minute sharp points. 



The apterous females which occasionally occur in the third generation 

 differ from those of the previous generation almost as much as the 

 second generation does from the first. They are considerably smaller, 

 measuring scarcely 2 mm. in length when fully mature, while the frontal 

 tubercles are more prominent and more like those of the winged form ; 

 the antennae, legs, and nectaries longer and more slender. This is in 

 fact the migratory form destitute of wings. 



The differences from this time on to the end of the season are so 

 small, compared with those of the spring and fall broods, as to be 

 almost imperceptible, notwithstanding that they may be found on quite 

 a number of different plants, so that the species may always most 

 readily be recognized. 



RETURN MIGRANTS, OR PUPIFEROUS FEMALES. 



The females of the fall brood which return again to the plum and 

 peach are in general appearance like those of previous generations. 

 They are, however, as a rule, somewhat larger and stouter, and all 

 markings are more intensified. The frontal tubercles are still more dis- 

 tinctly gibbous, and the nectaries are quite distinctly inflated toward 

 the end, giving them a somewhat clavate appearance. In many of 

 the specimens may also be noticed three small black spots or lines each 



