Sect. XVI. 16. t. OF INSTINCT. 137 



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

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

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

 moifture, and you may diftinftly fee the little worms move and 

 fuck up the water. When too much moiilure approaches their 

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

 er place of fafety. (Swammerd. Epii. ad Hift. 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- 

 pofits her eggs, and nicely clofing up the neft leaves them there 5 

 partly doubtlefs to aftift the incubation, and partly to fuppiy food 

 to her future young, (Derham. B. 4. c. 13. Ariltotle Hilt. 

 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 es"g 

 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 neft 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 lea animals, fee Botanic Garden, Part I. Note 

 XXVII. and is defigned for the purpofe of their transformation 

 as in the filk-worm, is ufed for conveying themfelves from highe*- 

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

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

 tangling his prey. Nor is it ftrange that fo much knowledge 

 mould 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 antennse, to a great degree of perfec- 

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

 accurate knowledge, and as fubtle invention, as the difcoverers 

 of human arts. 



- XVI. 1. If we were better acquainted with the hiftories of 

 thoie 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 not fo fimilar and uniform as they now 

 appear to us, but that they arofe in the fame manner from e:;- 



Vol. I. T peri^nie 



