804 



INSECTS INJURJOUS TO THE RASPBERRY. 



the interior, 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 of another cane, 

 to a height of five or six inches, where the larva, in pre- 

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

 ])lace 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 tlie 

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

 alis takes place, and when the time a})proaches for the nioth 

 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. 



Tlie 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 cuttino^ out the 

 infested portions. A parasitic insect 

 is said to attack these root-borers, and 

 probably destroys many of them. 



No. 175. — The Raspherry-root 

 Gall-fly. 



Bhodites radicum Osten Sacken. 



This is a small gall-fly, which pro- 

 duces a large browai gall on the roots, 

 a good representation of which is 

 given in Fig. 314. The swelling is composed of a yellow, 

 pithy su-bstance, scattered throughout which are a number of 

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



Fig. 314. 



