22 



LIFE HISTORY OF THE ALDER BLIGHT APHIS. 



MATURE STEM-MOTHER. 



The mature stem-mother, as seen on the leaves of the maple, is 

 densely covered with white wool, which is interspersed with long, 

 stout, white, and wavy strands. This secretion hides the insects com- 

 pletely from view, in consequence of which they resemble small 

 flakes of cotton. Their natural color is dark yellowish green or olive ; 

 the end of the body is black; the legs are of the color of the body, 

 with the apex of the femora and tarsi blackish. The antennae, includ- 

 ing the indistinct spur of the terminal joint, are 5- jointed; they 

 are rather short and reach about to the mesothorax. The first 



joint is stoutest and slightly the short- 

 est ; it is about as long as wide, with 

 the apex truncated; joints 2 and 4 are 

 somewhat longer than the first and sub- 

 equal in length; joints 3 and 5 are 

 longest and each of them is almost as 

 long as the two basal joints combined; 

 the four basal joints are of the color 

 of the body, while the fifth is blackish. 

 Length of body about 4 mm. ; diameter 

 about 3 mm. 



The mature stem-mother deposits be- 

 tween 100 and 400 larvse, all of which 

 form the first generation, which may 

 be termed the pupiferous generation, 

 since all of them gradually develop into 

 the winged or migratory form and, 

 after having attained maturity, migrate 

 to the leaves of alders to deposit their 

 larva?, which, in turn, become the pro- 

 .genitors of the second series, which has been described, by Dr. Asa 

 Fitch under the name of Eriosoma tessellata. 



Fig. 7. — Prociphilus tessellata: 

 Mature stem-mother and an- 

 tenna. (Original.) 



MIGRANT. 



The migrant, as well as the return migrant, is rather large and 

 stout. The head with its antennae, the thorax, and the legs are 

 black. The abdomen is of a greenish-brown or almost black color^ 

 being palest on the ventral side. The dorsum of the thorax and of 

 the abdomen is densely covered with a whitish woolly or cottony 

 secretion, which generally projects above the closed wings and be- 

 yond the end of the abdomen, while most of the secretion of the head 

 is generally rubbed off. The ventral side is covered with a whitish 



