SECT. XVI. 1 6. i. OF INSTINCT. 137 



low it, as the heat of the weather varies ; and in colder days lie 

 upon them in heaps for the purpoie of incubation : if their 

 manfion is too dry, they carry them to places where there is 

 moifture, and you may diftin Uy fee the little worms move and 

 fuck up the water. When too much moifture approaches their 

 neft, they convey their eggs deeper in the earth, or to ibme oth- 

 er place of fafety. (Swammerd. Epil. ad Hid. Infect, p. 153. 

 Phil. Tranf. No. 23. Lowthorp. V. 2 p. 7.) 



There is one fpecies of ichneumon-fly, that digs a hole in the 

 earth, and carrying into it two or three living caterpillars, de- 

 pofites her eggs, and nicely clofmg up the neft leaves them there ; 

 partly, doubtlefs, to aflift the incubation, and partly to fupply food 

 to her future young, (Derham. B. 4. c. 13. Ariftotle Hift. 

 Animal. L. 5. c. 20 ) 



A friend of mine put about fifty large caterpillars collected 

 from cabbages on fome bran and a few leaves into a box, and 

 covered it with gauze to prevent their efcape. After a few 

 days we faw, from more than three fourths of them, about eight 

 or ten little caterpillars of the ichneumon -fly come out of their 

 backs, and fpin each a fmall cocoon of filk, and in a few days 

 the large caterpillars died. This fmall fly it feems lays its egg 

 in the back of the cabbage caterpillar, which when hatched preys 

 upon the material, which is produced there for the purpofe of 

 making filk for the future neit of the cabbage caterpillar ; of 

 which being deprived, the creature, wanders about till it dies, 

 and thus our gardens are preferved by the ingenuity of this 

 cruel fly. 



This curious property of producing a filk thread, which is 

 common to fome fea animals, fee Botanic Garden, Part I, Note 

 XXVII. and is defigned for the purpofe of their transformation 

 as in the iiik-vvorm, is ufed for conveying the mfelves from higher 

 branches to lower ones of trees by ibme caterpillars, and to make 

 themfelves temporary nefts or tents, and by the fpider for en- 

 tangling his prey. Nor is it (trange that fo much knowledge 

 fhould be acquired by fuch fmall animals j fince there is reafon 

 to imagine, that thefe infects have the fenfe of touch, either in 

 their probofcis, or their antennae, to a great degree of perfec- 

 tion ; and thence may poflefs, as far as their fphere extends, as 

 accurate knowledge, and as fubtle invention, as the difcoverers 

 of human arts. 



XVI. i. If we were better acquainted with the hiftories of 

 thofe infects that are formed into focieties, as the bees, wafps, 

 and ants, I make no doubt but we mould find, that their arts 

 and improvements are nor fo fimilar and uniform as they now 

 appear to us, but that they rofe in the fame manner from ex- 



VOL. I. T pepence 



