SEASONAL HISTORY. 



23 



to dig around a flat pebble, and as a result passed through 3| inches 

 of soil. Another beetle left the cell Jul}^ 5 and emerged July 6, having 

 penetrated the soil for a distance of 1 inch. A third beetle left the 

 cell July 16 and emerged July 19, in which time it worked through 2 

 inches of soil. In the process of digging, the beetles make use of the 

 mandibles and to some extent also of the legs. The cells become 

 partly filled with earth by material being pushed behind and beneath 

 the beetle. In this process the channel is refilled and only a small 

 hole is left on the surface to indicate where the beetle emerged (PL 



Fig. 12. — Diagram showing time and development of a single individual of the grape root- worm 

 under average conditions, as observed in 1909, at North East, Pa. (Original.) 



I, fig. 10). In vineyards where the ground remains undisturbed such 

 openings can be readily found during the emergence period of the 

 beetle. 



In 1909 the first beetles observed in the field were collected by the 

 senior author June 28, and, since daily observations were made of 

 vineyard conditions, this record probably represents the earliest 

 occurrence of the beetle for the season. In the breeding cages the 



