"Hence will appear the 'loving kindness' of the Almighty, in setting such bounds, and keeping them within such limits as best answers the purpose for which He created them; and hence appears the necessity of their becoming food to other animals. Birds, fishes, and the smaller kinds of beasts, are at eternal war with them; but as all these would be insufficient of themselves to restrain and prevent them from multiplying too fast, other kinds of beings are instituted for this end, whose existence depends on their destruction. Of these, the species of insect I am describing, is the most singular, of which (genus) there are several sorts, differing greatly in size and shape. Some are furnished with three setæ or bristles at the extremity of their bodies, the middle one being a hollow tube, secured or fenced by the outer ones, through which they eject their eggs, after they have penetrated the body of the caterpillar they settle on. Some appear to have no bristles, others have them bent close under their bodies, and are not to be seen, unless closely examined. As their whole business appears to be the destroying the caterpillars of the butterfly and moth tribes, they are indefatigable in the pursuit of them; but as this is confined to the pregnant females, they are observed ranging about continually in search of the proper subjects to lay their eggs on; flying on every bush, and running with unwearied diligence on every twig, till they have arrived to the place where the scent of the caterpillar soon furnishes them with the certainty of its being there. Having thus discovered the animal it was in quest of, the Ichneumon immediately settles on it, with an intent to discharge its eggs; but the caterpillar being sensible, from a natural instinct, of its enemy's assault, bends its head backwards to the place where it feels itself attacked, and endeavours by various means, either by striking its head violently against the part, falling to the ground, or by some sudden contortion, to disengage itself: but this seldom happens, unless the Ichneumon is feeble, and unable to withstand the shocks of the caterpillar; in which case they will frequently relinquish their attack, and seek out some other subject, whose resistance they are more capable of encountering. On the other hand, if the Ichneumon is strong enough to withstand the efforts of the caterpillar, it either lays its eggs on the outside of the skin, as is the nature of some to do, or else perforates the body with the bristle before described, and immediately discharges an egg. Some of these Ichneumons quit the caterpillar upon the emission of an egg, but others continue thereon till they have emitted them all; which sometimes is more than an hundred. It is necessary to observe, that many caterpillars of moths and butterflies (the former more especially) are infested by a particular species of these Ichneumons, that confine themselves entirely to them alone, and never, that we know of, attack any other. Thus that of the Privet Hawk or Sphinx Ligustri of Linnæus, that of the Elephant Hawk or Sphinx Elpenor of the same author, &c. are always found to yield particular kinds of Ichneumons. Others, indeed, attack any kind of caterpillar belonging to the farinaceous-winged tribe; and, as I observed above, if not too powerful and strong for them, will there deposit their eggs.
"If the egg is laid on the body of the caterpillar, and not within it, a few days, by the warmth of the sun, ripens it to maturity; and then the young destroyer, directed by nature, eats its passage through the under-side of the egg, and passes into the body of the caterpillar, but if the egg is discharged into its body, it there ripens, unseen, to maturity. In either case, it lives on the substance or juices of its intestines; thriving and increasing in bulk, in a proportion equal to the creature it is doomed to kill. The caterpillar, also, notwithstanding its having thus received the means of a slow but certain death, increases in size, and, to outward appearance, in health; arriving to the period when it is to undergo its metamorphosis, and become a Chrysalis, in as much strength and vigour as any other of the species: but when the time arrives for its enlargement into its complete state, and to become a moth or butterfly, the Ichneumon makes its appearance; having arrived to its time of completion within the body of its supporter, and exhausted its juices by the nourishment drawn from it, leaving behind it a dry empty shell, in the form of a chrysalis.
"In this manner many of these Ichneumons exist. Others, when arrived to maturity, having lived within the bodies of the caterpillars, as described, eat their way out through its sides, and, crawling to a small distance, form round themselves cases of a substance like silk; wherein, having lain a few days, they quit their prisons in the shape of very small flies, some having two wings, others four."—Vide Goedartius, Albin, Wilks, Harris, &c.
POLISTES ANNULARIS.
Plate [XLIII]. fig. 6.
Order: Hymenoptera. Section: Diploptera. Family: Vespidæ, Leach.
Genus. Polistes, Fabr. Vespa, Linn. Drury.
Polistes Annularis. Fusca; genubus, antennarum apicibus margineque primi segmenti abdominis flavis. (Long. Corp. 1 unc.)
Syn. Vespa annularis, Linn. Syst. Nat. 1. 2. 950. 9. Fabr. Syst. Piez. 271. 3. (Polistes a.)
Vespa cincta, Drury, App. vol. 2.