INTRODUCTION. 9 



tion, and form a very considerable factor indeed in the great 

 system of checks and counterchecks by which existing Nature is 

 upheld, and room for constant change and progress is secured 

 without disturbing a general equilibrium of forces. That our crops 

 should sometimes sufi'er largely from their attacks is not sur- 

 prising ; and although insects are less numerous and destructive 

 in England than in many other countries, yet the perusal of a 

 work like Miss Ormerod's Manual of Injurious Insects is quite 

 suflScient to make it plain to even the most unentomological reader 

 that British crops are exposed to the attacks of a great number of 

 enemies, which the farmer would do well not to under-estimate 

 from their minuteness, but which he cannot combat successfully 

 without some technical knowledge of insects and their habits. 



A farmer or gardener who is ignorant of entomology is exposed 

 to great disadvantages. If his crops suffer, he is not unlikely to 

 mistake a harmless insect for the real depredator, or even to 

 destroy the beneficial insects which keep the others in check, 

 under the idea that they are the real authors of the mischief; 

 or again, by his own neglect to seize the fitting moment for 

 destroying the enemy, he may expose himself to very severe 

 losses, which might have been averted, or at least greatly lessened, 

 by a little timely precaution. A striking illustration of this 

 occurred a few years ago in South Russia, where a small species 

 of cockchafer {Anisoplia Austriaca, Herbst.) has lately been very 

 destructive. A vast swarm was blown into the sea, and washed 

 up on the beach in heaps in a half-torpid state, so that they might 

 easily have been collected and destroyed in large quantities. But 

 they were allowed to remain till they had recovered from their 

 bath and dried their Avings, when they flew inland to breed, and 

 to carry ruin and desolation throughout the district. 



Insects have many ways of defending themselves against their 

 numerous enemies. Those which are distasteful to birds are fre- 

 quently very conspicuous in their colours, and are often sluggish, 

 and weak flyers. Their uneatable character, however, being 

 apparent, they are easily recognised and passed over; and, as 

 already mentioned, ediljle species which sufficiently resemble them 

 share in their immunity. Other insects have different means 

 of concealing themselves, or of escaping observation ; while 

 many are able to defend themselves with their jaws or stings, 

 which are formidable even to the largest animals. Many insects 

 discharge an off'ensive fluid when alanncd or seized, and some even 



