MEANS OP DEFENCE OF INSECTS. 421 



a frog, and is probably the means of securing the nest from the attack of 

 many enemies. Dr. Arnold observed a species of bug (Scvtetlera) 

 abundant upon some polygamous plants which he could not determine, and 

 in all their different states. They were attended closely by hosts of ants, 

 and when disturbed emitted a very strong smell. One of these insects 

 ejected a minute drop of fluid into one of his eyes, which occasioned for 

 some hours considerable pain and inflammation. In the evening, however, 

 they appeared to subside ; but on the following morning the inflammation 

 was renewed, became worse than ever, and lasted for three days. 



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 Proscarabceus\ 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 (Elenophoms collaris) has likewise this faculty. 

 The lady-bird, we know, has been recommended as a cure for the tooth- 

 ache. Tins idea may have taken its rise from a secretion of this kind 

 being noticed upon it. I have observed that one species (Coccinella bipunc- 

 tata), when taken, ejects from its joints a yellow fluid, which yields a 

 powerful but not agreeable scent of opium. Asilus crabroniformis, a dip- 

 terous insect, once when I took it emitted a white milky fluid from its 

 proboscis, the joints of the legs and abdomen, 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 peculiar 

 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, some- 

 times 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 

 Willoughby has remarked a curious circumstance with respect to a water 

 beetle (Acilius stilcatus) 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 pores are visible, from which he affirms he 

 has often seen a milky fluid exuding 5 ; and what may confirm his state- 

 ment, I have more than once observed such a fluid issue from the male of 

 this genus. The caterpillar of the puss-moth (Cerura vinula), as well as 

 those of several other species, has a cleft in the neck between the head and 

 the first pair of legs. From this issues, at the will of the animal, a singular 

 syringe, laterally bifid ; the branches of which are terminated by a nipple 

 perforated like the rose of a watering-pot. By means of this organ, when 

 touched, it will syringe a fluid to a considerable distance, which, if it enters 

 the eyes, gives them acute, but not lasting pain. The animal when taken 



1 De Geer, ii. 734. 3 Eeamur, v. 96. 8 De Geer, ii. 937. 



4 Rosel, iv. 162. De Geer, i. 273. 5 Rai, Hi*t. Ins. 94. n. 3. 



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