MEANS OF DEFENCE OF INSECTS. 451 



culionida and other coleopterous insects, If they see any one approach, 

 contract their legs, and suffer themselves to fall from the leaf or other 

 surface on which they rest, among the grass or plants below, and thus 

 escape. To notice the ordinary motions of insects, which are often means 

 by which they avoid danger, would here be premature, since they will be 

 fully considered in a subsequent letter. I shall, therefore, only mention 

 the zitTzao^ flio-Jit of butterflies and the traverse sailino; of humble-bees, 

 which certainly render it more difficult for the birds to catch them while 

 on the wing. 



Noises are another means of defence to which insects have occasional 

 recourse. I have heard the lunar dung-beetle ( Copris lunaris) when disturb- 

 ed utter a shrill sound. Dynastes Oromedon, another of the lamellicorn 

 insects, was observed by Dr. Arnold to make, when alarmed, a kind of 

 creaking noise, which it produced by rubbing its abdomen against its 

 elytra. A third of the same tribe {Trox sahulosus) emits a small sibilant 

 or chirping noise, as I once observed when I found several feeding in a 

 ram's horn.^ 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 distinguishable from their ordinary sounds, may be regarded 

 as warning voices to those from whom they apprehend evil or an attack. 

 I have before observed that the death's-head hawk-moth (Acherontia 

 Atropos), when menaced 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, mournful cry, which with the superstitious has added to 

 the alarm produced by the symbol of death which signalizes 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.^ One of these 

 insects being once brought to a learned divine, who was also an entomol- 

 ogist, 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 

 putorius L.), which repels its assailants by the fetid vapor 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 odors 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 exam- 

 ples in almost every order; for, next to plants and vegetable substances, 

 insects, of any part of the creation, afford the greatest diversity of odors. 



• 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. 



* 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 com- 

 mits its depredation. Huber, ii. 299. 



