12 INTRODUCTION. 



persons. If we would therefore endeavour successfully to 

 combat the latter, it can only be done by the acquisition of 

 a knowledge of their habits, in every state of their existence ; 

 and, in this point of view, the study of Entomology becomes 

 of the highest importance. Let us take, for instance, the 

 case of the turnip-flea beetle (or turnip fly, as it is often 

 called — Haltica nemorum), and we find that all the numerous 



investigations of the Don- 

 caster Agricultural Associa- 

 tion have proved next to 

 useless, because the natural 

 history of the insect itself 

 was not ascertained. In like 

 manner it must be equally 



Turnip-flea Beetle. CvidcUt, that thc diff-UsioU of 



correct knowledge, and more 

 especially inquiries into the chemical properties of many 

 insects, hitherto considered useless, might be the means of 

 adding considerably to the list of benefits conferred by 

 insects on man. 



Amongst the Crustaceous Annulosa many species of crabs, 

 lobsters, prawns, and shrimps are employed to a very great 

 extent as articles of food ; and even amongst the winged or 

 true insects various species are found similarly serviceable. 



In the deserts of Africa and Asia, where the locusts ac- 

 quu'e a large size, those insects are employed, when dried 

 and preserved, as food. I have tasted locusts thus prepared, 

 and found them not unpalatable ; but they are said to pos- 

 sess very little nutritious quality, and to produce disease 

 when too much is eaten. The larvae or grubs of many large 

 beetles are also devoured by the negroes of India and Ame- 

 rica : and even the luxurious Romans were exceedingly fond 

 of a large fleshy grub which they called Cossus, and which is 

 sup])osed to have been either the larva of the Goat-moth 



