110 INSECTS AFFECTING THE GRAPE. 



Entomologists and horticulturists are indebted to 

 Dr. C. V. Riley for the elucidation of the life-history 

 of this curious insect, which, in his Seventh Report 

 as State Entomologist of Missouri, he has summar- 

 ized as follows : "'It hibernates mostly as a young- 

 larva torpidly attached to the roots, and so deepened 

 .in color as generally to be of a dull brassy-brown, 

 and, therefore, with difficulty perceived, as the roots 

 are often of the same color. With the renewal of 

 vine growth in the spring, this larva molts, rapidly 

 increases in size, and soon commences laying eggs. 

 These eggs in due time give birth to young, which 

 soon become virginal, egg-laying mothers, like the 

 first ; and like them, always remain wingless. Five 

 or six generations of these parthenogenetic, egg- 

 bearing, apterous mothers follow each other ; when 

 — about the middle of July, in this latitude — some 

 of the individuals begin to acquire wings. These 

 are all females, and, like the wingless mothers, they 

 are parthenogenetic. Having issued from the 

 ground, while in the pupa state, they rise in the air 

 and spread to new vineyards, where they deliver 

 themselves of their issue in the form of eggs or egg- 

 like bodies — usually- two or three in number, and 

 not exceeding eight — and then perish. These eggs 

 are of two sizes, the larger about 0.02 inch long, and 

 the smaller about three-fifths of that length. In the 

 course of a fortnight they produce the sexual indi- 

 viduals, the larger ones giving birth to females, the 

 smaller to males. These sexual individuals are born 



