MEANS OF DEFENCE OF INSECTS. 



195 



three legs of one side; turn themselves upon their back; 

 bend up their anus and show their sting accompanied by a 

 drop of poison. Sometimes they will even spirt out that 

 liquor. When in the nest, if it be attacked, they also beat 

 their wings violently and emit a great hum. 1 



These motions menace vengeance ; those of some other 

 insects are merely to effect their escape. Thus I have observed 

 that the species of the May-fly tribe (Trichoptera 2 ), when I 

 have attempted to take them, have often glided away from 

 under my hand — without moving their limbs that I could 

 discover — in a remarkable manner. 3 M. de Villiers informs 

 us that different species of moths of the genera Orthosia and 

 Cerastis never avail themselves of their wings to escape the 

 dangers which threaten them; but if you attempt to seize 

 them immediately let themselves fall to the ground, and then 

 begin running with such rapidity, that it is very difficult to 

 obtain possession of them. 4 And in like manner various 

 Curculionidce 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 or- 

 dinary 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 zigzag flight of butterflies and the traverse 

 sailing 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 disturbed utter a shrill sound. Dy- 

 nastes Oromedon, another of the lamellicorn insects, was ob- 

 served 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 sabulosus) 

 emits a small sibilant or chirping noise, as I once observed 



1 P. Huber in Linn. Trans, vi. 219. Kirby, Mon. Ap. Angl. i. 201. 



2 Kirby in Linn. Trans, xi. 87. note *. 



3 Evidently by the action of the numerous spines on the legs all directed 

 backwards, just as an ear of barley will mount up the sleeve of a coat. 



4 Ann. Soc. Ent. de France, xi. bull. xii. 



o 2 



