MEANS OF DEFENCE OF INSECTS. 46X 



destroyer of the helpless is defended by a thick coat, or rather mountain 

 composed of the skins, limbs, and down of these creatures. Reaumur, 

 in order to ascertain how far this covering was necessary, removed it, and 

 put the animal into a glass, at one time with a silk cocoon, and at another 

 with raspings of paper. In the first instance, in the space of an hour it 

 had clothed itself with particles of the silk; and in the second, being 

 again laid bare, it found the paper so convenient a material, that it madfe 

 of it a coat of unusual thickness.^ 



Insects in general are remarkable for their cleanliness ; — however filthy 

 the substances which they inhabit, yet they so manage as to keep themselves 

 personally neat. Several, however, by no means deserve this character : 

 and I fear you will scarcely credit me when I tell you that some shelter 

 themselves under an umbrella formed of their own excrement ! You will 

 exclaim, perhaps, that there is not a parallel case in all nature ; — it may 

 be so ; — yet as I am bound to confess the faults of insects as well as to 

 extol their virtues, I must not conceal from you this opprobrium. Beetles 

 of three different genera are given to this Hottentot habit. The first to 

 which I shall introduce you is one that has long been celebrated under 

 the name of the beetle of the lily (Crioctris merdigera, Cantaride de* 

 Gigli Vallisn.). The larvae of this insect have a very tender skin, which 

 appears to require some covering from the impressions of the external air 

 and from the rays of the sun ; and it finds nothing so well adapted to 

 answer these purposes, and probably also to conceal itself from the birds, 

 as its own excrement, with which it covers itself in the following manner. 

 Its anus is remarkably situated, being on the back of the last segment of 

 the body, and not at or under its extremity, as obtains in most insects. 

 By means of such a position, the excrement when it issues from the body, 

 instead of being pushed away and falling, is lifted up above the back in 

 the direction of the head. When entirely clear of the passage, it falls, 

 and is retained, though slightly, by its viscosity. The grub next, by a 

 movement of its segments, conducts it from the place where it fell to the 

 vicinity of the head. It effects this by swelling the segment on which 

 the excrement is deposited, and contracting the following one, so that it 

 necessarily moves that way. Although, when discharged, it has a longi- 

 tudinal direction, by the same action of the segments the animal contrives 

 to place every grain transversely. Thus, when laid quite bare, it will 

 cover itself in about two hours. There are often many layers of these 

 grains upon the back of the insect, so as to form a coat of greater diam- 

 eter than its body. When it becomes too heavy and stiff, it is thrown 

 off, and a new one begun. ^ — The larvae of the various species of the 

 tortoise-beetles (Cassida L.) have all of them, as far as they are known, 

 similar habits, and are furnished besides with a singular apparatus, by 

 means of which they can elevate or drop their stercorarious parasol so as 

 most effectually to shelter or shade them. The instrument by which they 

 effect this is an anal fork, upon which they deposit their excrement, and 

 which in some is turned up and lies flat upon their backs ; and in others 

 forms different angles, from very acute to very obtuse, with their body ; 

 and occasionally is unbent and in the same direction with it.^ In some 



» Reanm. iii. 391. 



« Reaum. iii. 220. Compare Vallisnieri, Esperienz. ed Osstrvaz. 195. Ed. 1726. 



» Reaum. 233. 



39* 



