On the Insects affecting the Turnip Crop, 



211 



beetle are not known, but may be expected to resemble those of 

 the striped turnip-fly. I will now describe this insect, the Alt lea 

 concinna, which is the same as the Altica dmtlpes of foreign 

 authors (fig. 9). 



It is more oval, convex, and shining than Altica nemorum, of a 

 greenish-black colour, more or less tinged with a brassy or copper 

 hue. The horns are only half as long as the body, and thickest 

 towards the extremity, of a pitchy colour, with a few rust- coloured 

 joints next the head : the trunk or thorax is thickly but very 

 finely punctured : the wing-cases are scarcely twice as broad as 

 the trunk, but three times as long, having ten lines of strongly- 

 impressed dots down each. The wings are ample ; the legs are 

 black, the shanks or tibiae are bright rust colour at the base ; the 

 hinder thighs are very stout (fig. 10 7?i) ; the intermediate and hinder 

 shanks are armed outside with a short acute tooth, below the 

 middle,"^ and fringed with hairs and toothed with spines (fig. n) ; 

 the feet are dusky, with four joints (fig. o) similar to those of 

 A. nemorum. Length from | to 1 line. 



It inhabits hedges, nettles, grass and turnip-fields ; and is 

 abundant throuo;hout En^iand and the south of Scotland in the 

 spring and summer. 



I had nearly forgotten to remxark that there is another little 

 beetle of the same genus, far from uncommon upon the turnips, 

 named Altica obscurella ; but as I am ignorant of its economy, I 

 refrain for the present from describing it. 



In the investigation of this subject I have thought it necessary 

 to consider every bearing that connects the beetle or fly with the 

 turnip-crop, that neither its habits nor any circumstance affecting 

 its economy might be overlooked ; but in treating of the other 

 insects I shall not have such a variety of materials to digest, which 

 will allow me to render their history more concise. I am now 

 induced to recapitulate the leading features contained in the fore- 

 going account, that they may be brought at one view before the 

 reader. 



There are at least two species of turnip-flies or beetles, the 

 striped and the brassy. 



The habits of the latter are not know^n. 



The eggs of the former are laid upon the under side of the 

 rough leaf, from April to September : they hatch in ten days. 



The maggots live between the two skins or cuticles of the 

 rough leaf, and arrive at maturity in sixteen days. 



The chrysalis is buried just beneath the surface of the earth, 

 where it remains about a fortnight. 



The beetles live through the winter in a torpid state, and revive 



* From this circumstance it has been recently named Chcetocnema concinna. 



