INSTINCT AND INTELLIGENCE. 



45. These precautions seem to be intended not only to protect 

 the eggs from wet and cold, but also to shade them from too 

 strong a light, which would be fatal to the young they contain. 

 It is doubtless for the same purpose that so many insects attach 

 their eggs to the lower in preference to the upper surface of leaves, 

 those which are placed on the upper surface being generally more 

 or less opaque.* 



46. The common white butterfly feeds upon the honey taken 

 from the nectary of a flower, but her larva, less delicate and more 

 voracious, devours the leaves of cabbage-plants. When we see, 

 therefore, this insect flying about and alighting successively upon 

 various plants, we imagine erroneously that she is in quest of her 

 own food, when in reality she is searching for the plant whose 

 leaves will form the proper nourishment for her future offspring. 

 Having found this, and having carefully ascertained that it has 

 not been pre-occupied by another of her species, she lays her eggs 

 upon it and dies. 



47. The young of the Gadfly (CEstrus Equi) are destined to live 

 in the stomach of a horse. This being stated, it may well be 

 asked how the insect fulfils that duty already described, which 

 consists in depositing the eggs upon the very spot where the young 

 will find their food ; for it can scarcely be imagined that the winged 

 insect will fly down a horse's throat to lay in its stomach. Yet 

 the parent accomplishes its object in a manner truly remarkable. 

 Flying round the animal, she lights successively many times upon 

 its coat, depositing several hundreds of her little eggs at the extre- 

 mity of the hairs, to which she glues them by a liquid cement 

 secreted in her body. This, however, would obviously fail to 

 accomplish the purpose of supplying the young with their proper 

 food, only to be found in the horse's stomach, to which, therefore, 

 it is indispensable that the eggs should be transferred. Marvel- 

 lous to relate, this transfer is made by the horse himself, who, 

 licking the parts of his hide to which the eggs are attached, takes 

 them, or the grubs evolved from them, if they have been already 

 hatched, upon his tongue, and swallows them mixed with saliva ; 

 thus conveying them to the only place where they can find their 

 proper food ! 



But it may be objected, that by this process no eggs or grubs 

 would find their way to the stomach, save those which might 

 chance to be deposited upon those particular parts of the horse's 

 body which it is accustomed to lick. There is, however, no 

 chance in the affair ; for the insect, guided by an unerring and 

 beneficent power, and as if foreseeing the inevitable loss of such of 



* Lacordaire, Int. Ent., vol i., p. 29. 

 134 



