156 HABITS AND INSTINCTS OF ANIMALS. CHAP. V. 



during summer, when swallows are chasing insects in 

 all directions. 



(176.) The noises emitted by insects are, doubtless, 

 in many instances, intended to effect their preservation 

 from enemies. The " drowsy hum " of beetles, hum- 

 ble-bees, and other insects, during flight, may tend to 

 preserve them from some of their aerial assailants. The 

 noises, however, which many of these insects produce, 

 when free from danger, are sensibly different from 

 those emitted when they are captured, and apprehensive 

 of life ; the latter sounds are always shriller and more 

 plaintive, as if the little creature had lost its joyous 

 hum of liberty, and was interceding, in piteous terms, 

 for its freedom : this modulation of voice is more espe- 

 cially observed among certain bees and flies; and is 

 sufficient to disarm as we have ourselves experienced 

 even the ardent zeal of the collector. This cry of 

 intercession is in no insect so remarkable as in the 

 death's-head sphinx (S. atropos}. Its cry is peculiarly 

 plaintive, and resembles that of a young child. A 

 learned divine, as Mr. Kirby states, who was also an 

 entomologist, had one of these insects brought to him 

 when he was unwell ; but he was so moved by its 

 plaintive noise, that, instead of devoting it to destruc- 

 tion, he gave the animal its life and liberty. 



(177.) Insects are provided with additional defences, 

 by emitting scents and fluids of the most repulsive 

 quality. Examples of these occur in nearly all the 

 orders. The Gyrinus natator emits a strong rancid 

 smell ; and that of the Slaps mortisaga is very disgust- 

 ing. Many Carabida exhale a disagreeable and pene- 

 trating odour ; that of the cockroach is very sickening, 

 and nearly as bad as the smell of the bed-bug. Nearly 

 the whole tribe of the Cimicides possess a very strong 

 and disagreeable scent : but the most remarkable insect 

 in this respect is the Hemerobius perla, a golden-eyed 

 and lace-winged insect, of a delicate green colour, very 

 common in gardens : this beauty, however, is counter- 

 balanced by a strong and most disgusting scent of 



