152 



COLEOPTERA OR BEETLES. 



MUSTARD-BEBTLE (PHiEDON BETULie). 



The Mustard-beetle or Black-jack often destroys turnip, rape, 

 and mustard to an alarming extent, especially in the Fen dis- 

 tricts, where it attacks both white and brown mustard. It is 

 where mustard is grown for seed that it makes its effects chiefly 

 felt. The Mustard-beetle belongs to the family Chri/somelidce, 

 which contains many injurious species. In length the Black- 

 jack is about IJ to 2 lines long, oval in form, and deep-blue to 

 dark-green in colour, with black legs and antennae. The females 

 come out in the spring, having hibernated during the winter 



Fir;. 70.— Mlstard-beetle (Pluedon betvlci;). 

 1, Attacked liat ; 2, ova; 8, 4, 6, larvii-, nat size, and magnifled ; 6 and 7, imago, 

 n.it. size, and ma^inified. (Curtis.) 



under grasses and in the dead hollow stems of plants, and at 

 once lay their eggs on tho leaves of Cruciferfe, where the 

 larvae feed off the leaves for a few days and then pupate in 

 the soil beneath, then in two weeks a new brood appears. The 

 larvae are dusky-yellow in colour and spotted, with sis legs and 

 a caudal foot, and are about i to } of an inch long : there is a 

 set of tubercles along each side, from which the larvae can pro- 

 trude yellow glands. 



Prevention and Remedies:. — Destruction of the stems of 

 mustard, &c., by deep ploughing, so as to bury the beetles that 

 hibernate in the stalks. Keeping clean the sides of all water- 

 ways, where numbers of tho beetles hibernate in the hollow 



