The study of natural history is one which, independent of the charm
it possesses to the inquisitive and contemplative mind, in affording
food for the cultivation of the highest qualities of the intellect, is
also beneficial in a moral point of view, as it insensibly brings the
cultivator of it to contemplate the power and goodness of his Creator.
It leads his thoughts from the petty affairs of life, and, making him
look with admiration and a feeling of love on every manifestation of
the Divine power which surrounds him, instils into his mind one of the
strongest principles of action desired by the Almighty--a feeling of
universal benevolence.
There cannot be a better illustration of this latter effect which I have
mentioned the study of natural history produces on the mind, than that
afforded us by the history of the birth and after life of the insect I
have headed this article with--“the Gadfly.” Strange and wonderful though
the transformations be to which the butterfly and many other individuals
of the insect world are subject, those of this little creature far
surpass them all.
Many of my readers are well acquainted with that fly which in the latter
part of summer is seen to be so annoying to the horse, buzzing about
him, and every now and then dashing itself with some degree of violence
against his sides and legs. This motion, to all appearance, is without
design; but a closer study of the habits of the insect will show that,
far from being the effect of chance, it is one of paramount importance
to the existence of the fly, as on it depends the continuation of its
species.
If attentively observed, it will be found that it is the female of this
fly alone who resorts to this peculiar motion; this she does to deposit
her eggs in the hair of the horse, to which they at once become attached
by a gelatinous fluid surrounding them; by this mucus they are enabled
to retain their hold for a few days, during which time they are fitted
to be hatched, and the slightest touch will liberate a little worm they
contain. The horse, in resorting to the common practice of licking
himself, breaks the egg, and the small worm contained in it adhering to
the tongue of the animal, is conveyed with the food into the stomach;
there it clings by means of hooks placed at either side of its mouth,
and its hold is so tenacious that it will be broken before it can be
detached. Here, in this strange abode, changing as it were its nature
in becoming a parasite, it remains for the whole of the winter, feeding
on the mucus of the stomach. At the end of the ensuing spring, having
reached its full perfection in this secondary state, led by that instinct
which regulates all the animated creation, from man to a monad, it
detaches itself from the cuticular coat, and is carried into the vilous
portion of the stomach with the food, passes out of it with the chyme,
and is at length evacuated with the feces. The larva or maggot, now a
second time changing its nature, seeks shelter in the ground, and after
some time becomes a chrysalis; in that helpless state it lies for some
weeks, when, bursting from its deathlike sleep, it wakes into life and
activity in the form of a perfect fly.
There is hardly a parallel to this wonderful chain of causes and effects,
and effects and causes, to be met with in all the varied and mysterious
workings of nature; scarcely one which exhibits so many acts apparently
so unconnected with the ultimate results.