416 MEANS OF DEFENCE OF INSECTS. 



horn. 1 The " drowsy hum" of beetles, humble-bees, and other insects in 

 their flight, may tend to preserve them from some of their aerial assailants. 

 And the angry chidings of the inhabitants of the hive, which are very dis- 

 tinguishable from their ordinary sounds, may be regarded as warning voices 

 to those from whom they apprehend evil or an attack. I have before ob- 

 served that the death's-head hawk-moth (Acheroniia Atropos), when me- 

 naced by the stings of ten thousand bees enraged at her depredations upon 

 their property, possesses the secret to disarm them of their fury. This 

 insect, when in fear or danger, is known to produce a sharp, shrill, mourn- 

 ful cry, which, with the superstitious, has added to the alarm produced by 

 the symbol of death which signalises its thorax. This cry, there is reason 

 to believe, affects and disarms the bees, so as to enable her to proceed in 

 her spoliations with impunity. 2 One of these insects being once brought 

 to a learned divine, who was also an entomologist, when he was unwell, he 

 was so much moved by its plaintive noise, that, instead of devoting it to 

 destruction, he gave the animal its life and liberty. I might say more upon 

 this subject of defensive noises, but I shall reserve what I have further to 

 communicate, to a letter which I purpose devoting to the sounds produced 

 or emitted by insects. 



You are acquainted with the singular property of the skunk (Viverra pu- 

 torius L.), which repels its assailants by the fetid vapour that it explodes ; 

 but perhaps are not aware that the Creator has endowed many insects 

 with the same property, and for the same purpose, some of which exhale 

 powerful or disagreeable odours at all times, and from the general surface 

 of their body; while they issue from others only through particular organs, 

 and when they are attacked. 



Of the former description of defensive scents there are numerous ex- 

 amples, in almost every order ; for, next to plants and vegetable sub- 

 stances, insects, of any part of the creation, afford the greatest diversity of 

 odours. In the Coleoptera order a very common beetle, the whirlwig 

 (Gyrinusnatator),vi\\\ infect your finger for a long time with a disagree- 

 able rancid smell ; while two other species, G. minutus and villosus, are 

 scentless. Those unclean feeders, the carrion beetles ( Silpha L.), as might 

 be expected from the nature of their food, are at the same time very fetid. 

 Pliny tells us of a Blatta, which, from his description, is evidently the 

 darkling-beetle (Blaps mortisaga), and which he recommends as an infallible 

 nostrum, when applied with oil extracted from the cedar, in otherwise in- 

 curable ulcers, that was an object of general disgust on account of its ill 

 scent, a character which it still maintains 3 ; which scent, from Mr.Thwaite's 

 investigation of the internal anatomy of this insect, proceeds from two 

 small oblong vesicles near the anus, the fluid contents of which, when they 

 are extracted and dissected under water, rise in a bubble to the surface, 

 and there becoming vaporised diffuse the fetid smell peculiar to the 

 species. Numbers of the ground-beetles (Eutrechina), that are found under 



1 Numerous other, beetles make the same kind of sound, either by the friction of 

 the head in the anterior prothoracic cavity, or by rubbing the narrowed front of the 

 mesothorax against the sides of the posterior prothoracic cavity, or the abdomen 

 against the elytra. 



8 Huber appears to be of this opinion ; he does not, however, lay great stress 

 upon it. Yet there seems no other way of accounting for the impunity with which 

 this animal commits its depredations. Huber, ii. 299. 



5 Hist. Nat. 1. xxix. c. 6. 



