304 



INSECTS INJURIOUS TO THE RASPBERRY. 



and gradually channels the cane to the root, in which it 

 spends the winter months, forming before spring cavities 

 of considerable extent. As the spring opens, it works its 

 way up again, usually through the interior -ef another cane, 

 to a heiglit of five or six inches, where the larva, i.i pre- 

 paring for the exit of the future moth, eats the cane in one 

 place nearly through, leaving a mere film of skin unbroken. 

 When full grown, it is about an inch long, of a pale-yellow 

 color, with a dark-brown head, and a few shining dots on 

 each segment of the body. Within the cane, and near the 

 spot specially prepared by the larva, the change to a chrys- 

 alis takes place, and when the time approaches for the moth 

 to escape, the chrysalis wriggles itself forward, and, pushing 

 against the thin skin remaining on the cane, ruptures it, and, 

 forcing its way through the opening, there awaits the escape 

 of the moth, which usually takes place within a few hours 

 afterwards. 



The injury thus done to the root is often followed by the 

 death of the canes, a result sometimes incorrectly attributed 

 to the severe cold of winter. Little 

 can be done towards the destruction 

 of this pest other than by laying 

 bare the roots and cutting out the 

 infested portions. A parasitic insect 

 is said to attack these root-borers, and 

 probably destroys many of them. 



No. 175. — The Raspberry-root 

 Gall-fly. 



Rliodites radicum Osten Sacken. 



This is a small gall-fly, which pro- 

 duces a large brown gall on the roots, 

 a good representation of which is 

 given in I'ig. 314. The swelling is composed of a yellow, 

 pithy substance, scattered throughout which are a number of 

 cells, each enclosing a small white larva, the progeny of the 



Fig. 3U. 



