INSECTS AFFECTING RHUBARB. 



INJURING THE STEM. 



The Rhubarb Curculio. 



Lixus concavus. 



Rhubarb stalks are frequently injured during 

 spring and early summer by a grayish or brownish 

 beetle that gnaws the sur- - J I|U u J ja^ m1 i tow ^ w , 



face (Fig. 96), and drills HIT 

 holes from which the gum- ; 



my sap exudes. This is '.w » ,';,--- "3 

 the Rhubarb Curculio, the 

 three later stages of which 

 are represented at Fig. 97. F i g . 96. Kimbaxb stem injured^ 

 The larva is a wrinkled 



legless grub of the form rejn'esented at a : it is three- 

 fourths of an inch long, white, with a brown head. 

 The pupa (6) is whitish and a little over half an inch 

 in length. The adult beetle, whose general form is 

 represented at c, is frequently covered with a yellow- 

 ish powder that gives it a distinct yellowish appear- 

 ance. When this powder is rubbed off the beetle is 

 grayish-brown. In the figure the straight lines in- 

 dicate the natural size of the specimens. 



The insect hibernates as an adult, and comes forth 

 in the spring to deposit its eggs in certain common 

 species of dock, especially Curly Dock (Rumex cris- 

 pus). The eggs are probably laid preferably in the 



