696 THE POPULAR SCIENCE MONTHLY. 



of the most extraordinary instances of foresight, through a mere 

 blind instinct, that have ever come under observation. 



The gadfly ( (Eustrus equi), whose larvae are the bots which inhabit 

 the intestines of the horse, gains for her progeny that comfortable po- 

 sition by entrapping the animal itself into introducing her eggs within 

 its stomach. For this purpose, she lays her eggs upon such portions 

 of the horse's body as he is in the habit of frequently licking, such as 

 knees, shoulders, etc. The unerring nature of her instinct is shown by 

 the fact that she never chooses as a nidus any portion of the body 

 which the horse is unable to reach with its tongue. Having thus 

 been introduced into their natural feeding-grounds, the bots there 

 pass their larval existence, until, it becoming time for them to assume 

 the pupal form, they go forth with the animal's dung to reach the 

 earth, burrow into it, and therein pass the insects' purgatory. 



Again, one of the grain-moths ( Gelechia cerealella) shows remark- 

 able instinct in adapting itself to circumstances according to the time 

 of year when it has to deposit its eggs. The first generation of 

 these moths, emerging in May from pupae which have lain in the gran- 

 aries through the winter, lay their countless eggs upon the as yet 

 ungathered corn, upon which their young play havoc until, having 

 passed through the necessary stages, they come out in the autumn as 

 the second generation amid the now stored-up grain. Now, however, 

 their instinct prompts them, not, like the first generation, to go forth 

 to the fields to seek the proper nest and future nourishment of their 

 young, but bids them deposit their eggs upon the store of wheat 

 ready at hand. Thus, two following generations of the same insect 

 are led by their instincts to different habits to suit the altered and, 

 in the last case, unnatural position of their infants' destined food- 

 supply. 



The interesting mason-wasp, having with great care and skill 

 bored out a cylindrical hole in some sunny sand-bank, deposits at the 

 bottom of this refuge her eggs. Next, provident mother as she is, she 

 seeks out about a dozen small caterpillars, always of the same species,. 

 and immures them alive in the pit, as food for her cruel children. In 

 making her selection of grubs to be thus buried alive, she rejects any 

 that may not have reached maturity ; not, we imagine, upon the 

 score of their not being so full-flavored, but because, when not full- 

 grown, they require food to keep them alive ; whereas, when of ma- 

 ture age, they will live a long time without nourishment, ready to 

 turn to chrysalides when opportunity occurs. 



These are but a few of the instances which might be adduced in, 

 illustration of this foresight in insects, which compensates for their not 

 being allowed in person to superintend the welfare of their offspring. 

 In many cases, it would be better for human progeny were their par- 

 ents thus endowed with an unerring instinct, rather than with an un- 

 certain will. — Chambers's Journal. 



