134 



COLEOPTEKA OK BEETLES. 



Mustard-beetle (PHyEDON betul/e). 



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 Olirysamelidm, 

 which contains many injurious species. In length the Black- 

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

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



Fig. 56. — JIustard-beetle (Phccdon hetvla:). 



1, Attacked leaf; 2, ova; 3, 4, 5, larva.', nat. size, aud magnified; 6 and 7, imago, 

 nat. size, and magnified. (Cui-tis.) 



come out in the spring, ha^'ing 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 

 larvse feed ofT 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 j.- to | of an inch long : there is a 

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

 trude a yellow gland. 



Prevention and ReiimUi'.s. — Destruction of the stems of 

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



