134 



COLEOPTEEA OR BEETLES. 



MnSTARD-BEETLE (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 hoth 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 Chrysomelidce, 

 which contains many injurious species. In length the Black- 

 jack is about 1 J to 2 lines long, oval in form, and deep-blue to 

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



Fjg. 56. — Mustard-beetle (Phmdtyii ietvlc^). 



1, Attacked leaf ; 2, ova ; 3, 4, 6, larvae, nat. size, and magnified ; 6 and 7, imago, 

 nat. size, and magnified. (Curtis.) 



come out in the spring, having hibernated during the winter 

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

 once lay their eggs on the leaves of Cruciferse, where the 

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

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

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

 a caudal foot, and are about 1 to ^ of an inch long : there is a 

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

 trude a yellow gland. 



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 the beetles hibernate in the hollow 



