INSECTS INJURIOUS TO THE GRAPE. 



ATTACKING THE EOOTS. 

 So. 122. — The Broad-necked Prionus. 



Prionus laticollis (Drury). 



This is a gigantic borer (Fig. 232), from two and a half to 

 three incK»s in length, of a yellowish-white color, with a 



Fia. 232. 



small, horny, reddish-brown head, and a bluish line down the 

 back, which cuts for itself a cylindrical hole through the 

 centre of the root of the vine, a little below the surface ; and 

 when the root is barely large enough to contain the larva, 

 nothing but a thin skin of bark is left, but this is always 

 found entire, so that the insect cannot be easily discovered. 

 It is probable that it lives in the larval state about three 

 years, and that it changes to a pupa (Fig. 233) within the 

 root towards the end of June. 



The beetle appears about the middle of July, and is known 

 as the Broad-necked Prionus. Fig. 234 represents the female, 

 which measures from an \\w\\ and a quarter to an inch and 

 three-quarters in length, and is of a brownish-black color, with 

 strong, thick jaws; the antennae are rather slender; the thorax 

 is short and wide and armed at the sides with three teeth. The 

 wing-covers have three slightly-elevated lines on each, and 



227 



