240 MEANS or DEFENCE OF INSECTS. 



have observed that the species of the May-fly tribe 

 {Phri/gmieo^ L., Triclioptera, K."), when I have at- 

 tempted to take them, have often glided away from un- 

 der my hand — without moving their limbs that I could 

 discover — in a remarkable manner. I once observed a 

 weevil (Brach^rhinus, F.) upon a rail, which, when it 

 saw me, slided sideways, and then rolled off. To notice 

 the ordinary motions of insects, which are often means 

 by which they escape from danger, would here be prema- 

 ture, 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. 



JVoises are another mean of defence to which insects 

 have occasional recourse. 1 have heard the lunar 

 dung-beetle (Copris limaris, F.) when disturbed utter 

 a shrill sound. Geotri/pes Oromedon, F., another of 

 the ScarabceidcB, was observed by Dr. Arnold to make, 

 when alarmed, a kind of creaking noise, which it pro- 

 duced by rubbing its abdomen against its elytra. A 

 third of the same tribe, Trox sabulosus, F., 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 in- 

 sects 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 distin- 

 guishable 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 



* Kiiby in Linn. Trnns. xi. 87, note *. 



