242 MAINE AGRICULTURAL EXPERIMENT STATION, 1912. 



leaf migrants at the base of water shoots of an uninfested 

 mountain ash on the Campus. As the migrants are much more 

 docile about sundown than earlier in the clay this was done 

 about 7 P. M. They moved but little, most of them creeping to 

 the ventral side of a leaf and remaining there ; and during the 

 night producing nymphs which sought the leaf axils of the 

 water shoots so that by the afternoon of June 22, the tiny 

 nymphs had already fed enough and secreted enough white wax 

 to give the typical "woolly" appearance to the young colonies. 

 These and the progeny thrived on the mountain ash in a 

 perfectly normal way. 



SEQUENCE OF GENERATIONS. DESCRIPTIVE. 



Fig. 443. Stem mother. 

 (From Riley.) 



Hgg 0.5 mm. long, gamboge- 

 yellow, inclining to brown in 

 color, with no especial external 

 sculpture. In crevices under 

 elm bark. 



Stem mother: Pale yellowish- 

 red, with black members when 

 first hatched; the red deepening 

 and becoming purplish or livid 

 with age. When mature, aver- 

 aging 3-5 mm. in length, globose 

 or pyriform, with subobsolete 

 honey-tubes and six dorsal rows 

 of darker piliferous and tuber- 



culous spots. Antenna 5-jointed, joint 3 more than equaling 

 4 and 5 together in length. Causing and inhabiting elm leaf curl. 



Second generation. Apterous viviparous forms which do not 

 become so large as the stem mother. The antenna is normally 

 6-jointed (Fig. 461). Inhabiting leaf curl and giving birth to 

 migrants. 



Third generation. Winged viviparous female: Body dusky, 

 the abdomen slightly reddish; legs either dusky or yellowish 

 red. Antennae as long as head and thorax together, dusky, 

 rarely yellowish, not pilose, but with a few short setous points ; 

 6-jointed. The annulation of the joints in different collections 

 and from different localities varies greatly. Figs 451, 452, 454. 





