448 



THE MANGOLD-WTJRZEL CROP. 



to the crown of the root, the plant being in that case 

 effectually destroyed. In 1846, M. Bazin noticed that 



1 and 2. Young and full-grown larvae of Silpha opaca (natural size) devour- 

 ing a mangold leaf. 3 and 4. Do. magnified (female and male). 5. The 

 beetle flying (female). 6. Do. male, slightly magnified. 



the leaves of his mangold crop were nibbled into small 

 round holes, which, on examining them closely, he found 

 were due to the larvae of the " clouded shield-beetle " 

 Gassida nebulosa which infested the under side of the 

 leaves. The larvae are of a pretty green colour, marked 

 with white, and the margins are armed with barbed yel- 

 low spines ; they have at the extremity of the body two 

 long spreading tails, which the insect keeps turned over 

 its back when at rest, by way of shelter, and also as a 

 protection against the attack of parasites, to which, how- 

 ever, it frequently falls a victim. The leaves of the plant 

 are also liable to injury from the " mangold- wurzel fly" 

 Anthomyia betce. The maggots are of an ashy gray 

 colour, and as soon as they are hatched, make their way 

 into the interior of the leaf, feeding on the pulpy sub- 

 stance (parenchyma), eating through the integuments, 

 and giving the leaf a blistered appearance. These, like 

 those of the turnip-leaf miner (p. 321), are readily de- 

 stroyed by merely pinching the leaves containing them, 

 when, unless the leaves have been greatly injured by 

 them, they recover, and the roots are not checked in their 



