506 



HISTORY OF INSECTS. 



and the strongest will devour the weak in pre- 

 ference to their vegetable food. That which 

 lives upon the oak is found to seize any of its 

 companions, which it conveniently can, by the 

 iirst rings, and inflict a deadly wound : it then 

 feasts in tranquillity on its prey, and leaves 

 nothing to the animal but the husk. 



But it is not from each other they have the 

 most to fear, as in general they are inoffensive ; 

 and many of this tribe are found to live in a 

 kind of society. Many kinds of flies lay their 

 eggs either upon or within their bodies ; and, 

 as these turn into worms, the caterpillar is seen 

 to nourish a set of intestine enemies within its 

 body, that must shortly be its destruction : 

 Nature having taught flies, as well as all other 

 animals, the surest methods of perpetuating 

 their kind. " Towards the end of August," 

 says Reaumur, "I perceived a little fly, of a. 

 beautiful gold colour, busily employed in the 

 body of a large caterpillar, of that kind which 

 feeds upon cabbage. I gently separated that 

 part of the leaf on which these insects were 

 placed, from the rest of the plant, and placed 

 it where I might observe them more at ease. 

 The fly, wholly taken up by the business in 

 which it was employed, walked along the 

 caterpillar's body, now and then remaining 

 fixed to a particular spot. Upon this occasion, 

 I perceived it every now and then dart a sting, 

 which it carried at the end of its tail, into the 

 caterpillar's body, and then draw it out again, 

 to repeat the same operation in another place. 

 It was not difficult for me to conjecture the 

 business which engaged this animal so ear- 

 nestly ; its whole aim was to deposit its eggs 

 in the caterpillar's body ; which was to serve 

 as a proper retreat to bring them to perfection. 

 The reptile thus rudely treated, seemed to 

 bear all very patiently, only moving a little 

 when stung too deeply ; which, however, the 

 fly seemed entirely to disregard. I took par- 

 ticular care to feed this caterpillar ; which 

 seemed to me to continue as voracious and 

 vigorous as any of the rest of its kind. In 

 about ten or twelve days, it changed info an 

 aurelia, which seemed gradually to decline, 

 and died : upon examining its internal parts, 

 the animal was entirely devoured by worms ; 

 which, however, did not come to perfection, 

 as it is probable they had not enough to sustain 

 them within." 



What the French philosopher perceived 

 upon this occasion is every day to be seen in 

 several of the larger kinds of caterpillars, 

 whose bodies serve as a nest to various flies, 

 that very carefully deposit their eggs within 

 them. The large cabbage caterpillar is so 

 subject to its injuries, that, at certain seasons, 

 it is much easier to find them with than with- 

 out them. The ichneumon fly, as it is called, 

 particularly infests these reptiles, and pre- 



vents their fecundity. This fly is of all others 

 the most formidable to insects of various kinds. 

 The spider, that destroys the ant, the moth, 

 and the butterfly, yet often falls a prey to the 

 ichneumon ; who pursues the robber to his 

 retreat, and despising his net, tears him in 

 pieces, in the very labyrinth he has made. 

 This insect, as redoubtable as the little quad- 

 ruped that destroys the crocodile, has received 

 the same name ; and from its destruction of 

 the caterpillar tribe, is probably more service- 

 able to mankind. This insect, I say, makes 

 the body of the caterpillar the place for depo- 

 siting its eggs, to the number of ten, fifteen or 

 twenty. As they are laid in those parts 

 which are not mortal, the reptile still continues 

 to live and to feed, showing no signs of being 

 incommoded by its new guests. The cater- 

 pillar changes its skin, and sometimes under- 

 goes the great change into an aurelia : but still 

 the fatal intruders work within, and secretly 

 devour its internal substance : soon after they 

 are seen bursting through its skin, and moving 

 away, in order to spin themselves a covering, 

 previous to their own little transformation. It 

 is indeed astonishing sometimes to see the 

 number of worms, and those pretty large, that 

 thus issue from the body of a single cater- 

 pillar and eat their way through its skin : but 

 it is more extraordinary still that they should 

 remain within the body, devouring its entrails, 

 without destroying its life. The truth is, they 

 seem instructed by nature not to devour its 

 vital parts ; for they are found to feed only 

 upon that fatty substance which composes the 

 largest partof the caterpillar's body. When this 

 surprising appearance was first observed, it was 

 supposed that the animal thus gave birth to a 

 number of flies different from itself; and that the 

 same caterpillar sometimes bred an ichneumon, 

 and sometimes a butterfly : but it was not till 

 after more careful inspection it was dis- 

 covered, that the ichneumon tribe were not the 

 caterpillar's offspring, but its murderers. 



CHAP. V. 



OF THE SILKWORM. 



HAVING mentioned, in the last chapter, the 

 damages inflicted by the caterpillar tribe, we 

 now come to an animal of this kind, that alone 

 compensates for all the mischief occasioned by 

 the rest. This little creature, which only 

 works for itself, has been made of the utmost 

 service to man ; and furnishes him with a 

 covering more beautiful than any other ani- 

 mal can supply. We may declaim indeed 

 against the luxuries of the times, when silk 

 is so generally worn ; but were such garments 



