204 



MEANS OF DEFENCE OF INSECTS. 



Other insects, when under alarm, discharge a fluid from 

 the joints and segments of their body. You have often seen 

 what has been called the unctuous or oil beetle (Meloe Pro- 

 scarabceus), and I dare say, when you took it, have observed 

 orange-coloured or deep-yellow drops appear at its joints. 

 As these insects feed upon acrid plants, the species of crow- 

 foot or Ranunculus, it is probable that this fluid partakes of 

 the nature of their food, and is very acrimonious — and thus 

 may put to flight its insect assailants or the birds, from neither 

 of which it could otherwise escape, being a very slow and 

 sluggish, and at the same time very conspicuous animal. 

 Another beetle (Elenophorus collaris) has likewise this fa- 

 culty. — The lady-bird, we know, has been recommended as 

 a cure for the tooth-ache. This idea may have taken its rise 

 from a secretion of this kind being noticed upon it. I have 

 observed that one species ( Coccinella bipunctata), when taken, 

 ejects from its joints a yellow fluid, which yields a powerful 

 but not agreeable scent of opium. — Asilus crabroniformis, 

 a dipterous insect, once when I took it, emitted a white 

 milky fluid from its proboscis, the joints of the legs and ab- 

 domen, and the anus. The common scorpion-fly (Raphidia 

 ophiopsis) likewise, upon the same occasion ejects from its 

 proboscis a brown and fetid drop. 1 Some insects have pe- 

 culiar organs from which their fluids issue, or are ejaculated. 

 Thus the larvae of saw-flies, when taken into the hand cover 

 themselves with drops, exuding from all parts of their body, 

 of an unpleasant penetrating scent. 2 That of Cimbex lutea, 

 of the same tribe, from a small hole just above each spiracle, 

 syringes a similar fluid in horizontal jets of the diameter of 

 a thread, sometimes to the distance of more than a foot. 3 — 

 The caterpillar of the great emperor moth (Saturnia Pavonia 

 major) also spirts out, when the spines that cover them are 

 touched, clear lymph from its pierced tubercles. 4 — Willughby 

 has remarked a curious circumstance with respect to a water- 

 beetle {Acilius sulcatus), which ought not to be overlooked. 

 A transverse line of a pale colour is observable upon the 

 elytra of the male ; where this line terminates certain oblong 



« De Geer, ii. 734. 2 Reaumur, v. 96. 3 De Geer, ii. 937. 



4 Rose], iv. 162. De Geer, i. 273. 



