GALL APHIDS OF THE ELM. 21/ 



0.13 mm. -0.145 mm.; VI, 0.085 nim. -0.095 mm. Annulations 

 not completely circling the joints, these vary in number but are 

 approximately III, 9 to 11; IV, 2 to 3 ; V, 6 ; VI, 3. Annula- 

 tions on VI faint, very irregular and often run together. Beak 

 extends a little caudad of ist coxa. Thorax dark dorsally and 

 ventrally. Wings with venation as usual for Tetranenra. Veins 

 dark and heavy, Cu and ist A being conspicuously heavier than 

 the others, stigma dark. Wing expanse 6 mm. Abdomen dark 

 green. Total length of body 2.15 mm. Measurements from 

 balsam mounts. Color description from individuals removed 

 from gall before flight. July 6, 1909. They grow even darker 

 with age. 



Habitat, — about 60 individuals developing in gall as progeny 

 of single stem mother and after attaining wings migrating from 

 gall. (Figs. 164, 165). 



Maine collection numbers of type specimens Aphid 22-05, 

 -Aphid 53-09. 



Pnpcc. The second generation while in the pupal stage vary 

 from dark purplish individuals to light individuals having dusky 

 head and prothorax ; white pellucid thorax, wing pads, an- 

 tenn?e, and legs ; and pale tan abdomen. Body somewhat floc- 

 culent. Antenna 6-jointed. (Fig. 166). Aphid No., 53-09. 



Galls. The galls are pedunculated sacs with height of from 

 less than ^ to i inch. They are bright yellowish green with a 

 varnished look and much paler than the elm leaf. The older 

 galls have some pinkish tints. The opening into the gall which 

 is on the ventral side of leaf is surrounded with pale fuzzy 

 hair which extends a short distance up into the gall. Inside 

 wall of gall with slight longitudinal ridges. The galls occurred 

 in numbers from i to 36 on single leaf, \\niere most numerous 

 some of the galls were small and not typical in shape. They 

 occur on the dorsal surface of leaf between the lateral veins. 

 No galls were found exactly on the mid rib, though they were 

 often very near. The mature gall as a rule had an irregular 

 circular liole in the side through which the migrants made exit. 



Biological. 



On Tunc 26, 1909, the galls about Orono were pretty well 



grown. J\Iost of the stem mothers at this date were not quite 



mature, — had not begun to produce. By July 6 some of the 



stem mothers were shriveled and were through producing, oth- 



