ATTACKING THE CANES. 



307 



Fig. 316. 



No. 177. — The Red-necked Agrilus. 



Agrilus rujicollis (Fabr.j. 



In the spring-time, when raspberry and blackberry canes 

 are being pruned, they will often be observed swollen in 

 places to the length of an inch or more, in the manner shown 

 in Fig. 316. This swelling is a 

 pithy gall, and has been named 

 the Raspberry Gouty-gall, Rubi 

 -podagra Riley, and is produced 

 by the irritation caused by the 

 j)resence of the larva of the red- 

 necked Agrilus. The swollen 

 portions are not smooth, as the 

 healthy ones are, but have the 

 surface roughened with numer- 

 ous brownish slits and ridges, 

 and when the ridges are cut into 

 with a knife, there will be found 

 under each of them the passage- 

 way of a minute borer, and 

 either in the channel or in the 

 softsubstance adjoining, the larva 

 will usually be found. Fig. 317 

 represents tlie nearly full-grown 

 larva magnified, the hair-line at 

 the side indicating its natural 

 size. Its body is almost thread- 

 like, and of a pale-yellowish or whitish color, with the ante- 

 rior segments enlarged and flattened. The head is small and 

 brown, the jaws black, and the tail is armed with two slender, 

 dark-bi*own horns, each having three blunt teeth on the inner 

 edge. When full grown, it measures about six-tenths of an 

 inch long. While young it inhabits chiefly the sap-wood, 

 and, foil )wing an irregular, spiral course, frequently girdles 

 and destroys the cane ; usually several larvae will be found 



