would prefer the geographical treasures of Saxton or Speed, in spite of their ink and alum, to the freshest rind of the flax plant.—The larva of a little fly (Oscinis cellaris), whose economy, as I can witness from my own observations, is admirably described by Mentzelius[703], disdains to feed on any thing but wine or beer, which like Boniface in the play it may be said both to eat and drink, though, unlike its toping counterpart, indifferent to the age of its liquor, which whether sweet or sour is equally acceptable.
A diversity of food almost as great may be boasted by the insects which feed on animal substances. Some (flesh-flies, carrion-beetles, &c.) devour dead carcases only, which they will not touch until imbued with the haut gout of putridity. Others, like Mr. Bruce's Abyssinians, preferring their meat before it has passed through the hands of the butcher, select it from living victims, and may with justice pride themselves upon the peculiar freshness of their diet. Of these last, different tribes follow different procedures. The Ichneumons devour the flesh of the insects into which they have insinuated themselves. Some of the Œstri, fixed in a spacious apartment beneath the skin of an ox or deer, regale themselves on a purulent secretion with which they are surrounded. Others of the same tribe, partial to a higher temperature, attach themselves to the interior of the stomach of a horse, and in a bath of chyme of 102 degrees of Fahrenheit revel on its juices. The various species of horse-flies dart their sharp lancets into the veins of quadrupeds, and satiate themselves in living streams; while the gnat, the flea, the bug, and the louse, plunge their proboscis even into those of us lords of the creation, and banquet on "the ruddy drops which warm our hearts." Some make their repast upon birds only, as the fly of the swallow, and other Ornithomyiæ, and the bird-louse; insects nearly allied, though one is dipterous and the other apterous. And a most singular animal belonging to the latter tribe (Nycteribia Vespertilionis) revenges upon the bat its ravages of the insect world[704]. Another numerous class kill their prey outright, either devouring its solid parts, as the predaceous and rove-beetles, &c., or imbibing its juices only, as the infinite hordes of the field-bug tribe. And the larvæ of the gnat, chameleon (Stratyomis), and other flies aquatic in that state, the leviathans of the world of animalcules, swallow whole hosts of these minute inhabitants of pools and ponds at a gulp, causing with their oral apparatus a vortex in the water, down which myriads of victims are incessantly hurried into their destructive maw.
But not only animals themselves, almost every animal substance that can be named is the appropriate food of some insect. Multitudes find a delicious nutriment in excrements of various kinds. Matters apparently so indigestible as hair, wool, and leather, are the sole food of many moths in the larva state (Tinea tapetzella, pellionella, &c.). Even feathers are not rejected by others; and the grub of a beetle (Anthrenus Musæorum), with powers of stomach which the dyspeptic sufferer may envy, will live luxuriously upon horn[705].
For the most part, insects feeding upon animal substances will not touch vegetables, and vice versâ. You must not however take the rule without exceptions. Many caterpillars (as those of Thyatira derasa, Chariclea Delphinii, &c.), though plants are their proper food, will occasionally devour other caterpillars, and sometimes even their own species. The large green grasshopper (Acrida viridissima), and probably others of the order, will eat smaller insects as well as its usual vegetable food[706]; so also will the larvæ of many Phryganeæ. Allantus marginellus, as I was last summer amused by witnessing, like many Scatophagæ, sips the nectar of umbelliferous plants only till a fly comes within its reach, pouncing upon which it gladly quits its vegetable for an animal repast. Anobium paniceum, which ordinarily feeds upon wood, was, as I before mentioned, once found by Mr. Sheppard in great abundance living upon the dried Cantharides (Cantharis vesicatoria) of the shops. On the other hand, Necrophorus mortuorum, which subsists on carcases, and many other carnivorous species, will make a hearty meal of a putrid fungus; Ptinus Fur devours indifferently dried birds or plants, not refusing even tobacco; and from the impossibility that one of a million of the innumerable swarms of gnats which abound in swampy places, particularly in regions which but for them would be lost to sensitive existence, should ever taste blood, it seems clear that they are usually contented with vegetable aliment. Indeed the males, as well as those of the horse-fly of which even the females readily imbibed the sugared fluid offered to them by Reaumur[707], never suck blood at all; so that they must either feed on vegetable matter, which in fact I have observed them to do, or fast during their whole existence in the perfect state.
Though insects, generally considered, have thus a much more extensive bill of fare than the larger animals, each individual species is commonly limited to a more restricted diet. Many both of animal and vegetable feeders are absolutely confined to one kind of food, and cannot exist upon any other. The larva of Gasterophilus Equi can subsist no where but in the stomach of the horse or ass, which animals therefore this insect might boast with some show of reason to have been created for its use rather than for ours, being to us useful only, but to it indispensable. The larvæ of Syrphus Pyrastri according to De Geer eat no other Aphis but that of the rose[708]. Most Ichneumons and Sphecina prey each upon a single species of insect only, which therefore they would seem to have been formed for the express purpose of keeping within due limits. Reaumur mentions having once found in a parcel of decaying wood the nests of six different kinds of the latter tribe, each of which was filled with flies of a distinct species[709]. Cerceris auritus and Philanthus lætus in the larva state feed solely on the weevil tribe of Coleoptera, the latter being restricted even to the short-rostrum'd family, as Otiorhynchus raucus, &c.[710], while Bembex rostrata, another hymenopterous insect, selects flies, as Musca Cæsar, &c.[711]
A very large proportion of species, however, are able to subsist on several kinds of food. Amongst the carnivorous tribes, it is indifferent to most of those which prey upon putrid substances from what source they have been derived: and the predaceous insects, such as the Libellulina, Telephorus, Empis, the Araneidæ, &c. will attack most smaller insects inferior to them in strength, not excepting in many instances their own species. The wax-moth larva (Galleria Cereana) will for want of wax eat paper, wafers, wool, &c.[712]: another Tinea described by Reaumur, and before adverted to, attacks chocolate[713], which cannot have been its natural food, even selecting that most highly perfumed; and the Tineæ which devour dressed wool, but happily for the farmer and wool-stapler refuse it when unwashed, must have existed when no manufactured wool was accessible.—The vegetable feeders are under greater restrictions, yet probably the majority can subsist on different kinds of food. This is certainly true of most lepidopterous larvæ, several of which as well as many Coleoptera (Haltica oleracea, &c.) are polyphagous, eating almost every plant. It is worthy of remark, however, that when some of these have fed for a time on one plant they will die rather than eat another, which would have been perfectly acceptable to them if accustomed to it from the first[714]. Here too it must be borne in mind, that by far the greater part of insects feed upon different substances in their different states of existence, eating one kind of food in the larva and another in the imago state. This is the case with the whole Order Lepidoptera, which in the former eat plants chiefly, in the latter nothing but honey or the sweet juices of fruit, which they have often been observed to imbibe; and the same rule obtains also in regard to most dipterous and hymenopterous insects. Those which eat one kind of food in both states, are chiefly of the remaining orders.
I have said that insects, like other animals, draw their subsistence from the vegetable or animal kingdoms. But I ought not to omit noticing that some authors have conceived that several species feed upon mineral substances[715]. Not to dwell upon Barchewitz's idle tale of East Indian ants which eat iron[716], or on the stone-eating caterpillars recorded in the Memoirs of the French Academy[717], which are now known to erode the walls on which they are found, solely for the purpose of forming their cocoons; Reaumur and Swammerdam have both stated the food of the larvæ of Ephemeræ to be earth, that being the only substance ever found in their stomachs and intestines, which are filled with it. This supposition, which if correct renders invalid the definition by which Mirbel (and my friend Dr. Alderson of Hull long before him) proposed to distinguish the animal and vegetable kingdoms, is certainly not inadmissible; for, though we might not be inclined to give much weight to Father Paulian's history of a flint-eater who digested flints and stone[718], the testimony of Humboldt seems to prove that the human race is capable of drawing nutriment from earth, which, if the odious Ottomaques can digest and assimilate, may doubtless afford support to the larvæ of Ephemeræ. Yet after all it is perhaps more probable that these insects feed on the decaying vegetable matter intermixed with the earth in which they reside, from which after being swallowed it is extracted by the action of the stomach: like the sand that, from being found in a similar situation, Borelli erroneously supposed to be the food of many Testacea, though in fact a mere extraneous substance.
The majority of insects, either imbibing their food in a liquid state, or feeding on succulent substances, require no aqueous fluid for diluting it. Water, however, is essential to bees, ants, and some other tribes, which drink it with avidity; as well as in warm climates to many Lepidoptera, which are there chiefly taken in court yards, near the margins of drains, &c. Even some larvæ which feed upon juicy leaves have been observed to swallow drops of dew; and one of them (Odenestis potatoria), which (according to Goedart) after drinking lifts up its head like a hen, has received its name from this circumstance. That it is not the mere want of succulency in the food which induces the necessity of drink, is plain from those larvæ which live entirely on substances so dry that it is almost unaccountable whence the juices of their body are derived. The grub of an Anobium will feed for months upon a chair that has been baking before the fire for half a century, and from which even the chemist's retort could scarcely extract a drop of moisture; and will yet have its body as well filled with fluids as that of a leaf-fed caterpillar.
By far the greater part of insects always feed themselves. The young however of those which live in societies, as the hive- and humble-bees, wasps, ants, &c. are fed by the older inhabitants of the community, which also frequently feed each other. Many of these last insects are distinguished from the majority of their race, which live from day to day and take no thought for the morrow, by the circumstance of storing up food. Of those which feed themselves, the larger proportion have imposed upon them the task of providing for their own wants; but the tribe of Spheges, wild bees, and some others, are furnished in the larva state by the parent insect with a supply of food sufficient for their consumption until they have attained maturity.
As to their time of feeding, insects may be divided into three great classes: the day-feeders, the night-feeders, and those which feed indifferently at all times. You have been apt to think, I dare say, that when the sun's warmer beams have waked the insect youth, and