[164] In the island of Senegal they do incredible mischief; they gnaw linen, sheets, wood, paper, books, and, in short, whatever comes in their way; they attack even the aloes, the bitterness of which keeps off all other insects. Adanson’s Voyage, p. 296.
All those of the next genus, mantis, are foreign; some of them are extremely remarkable and curious, and from their particular shape, as well as their colour, have been called walking leaves; they are found in meadows, on grass, and on the leaves of plants and trees. The grylli mostly reside in meadows and fields among the herbage; however formidable the mischief occasioned by the blattæ may appear, it is trivial when compared with the ravages of the gryllus migratorius or locust.[165] One species of this genus, the gryllus domesticus, resides in houses, particularly where there are ovens, and entertains the inhabitants with the chirping sound it emits. Most of the fulgoræ or lanthorn-flies are discoverable by the light which proceeds from them; these, like the mantæ, are foreign, and many of them equally curious. The cicadæ are found on trees and plants; the notonectæ and nepæ frequent rivers, lakes, and standing waters. There is scarce a person who has resided any time in a very populous place, but knows where to find one species of the next genus or cimex, viz. that distinguished by the name of cimex lectularius or bed bug.[166]
[165] Adanson relates, that soon after his arrival in Senegal, he was a witness to the mischief done by locusts, that scourge so dreadful to hot climates! Towards eight o’clock in the morning there suddenly arose a thick cloud that darkened the air, and obstructed the rays of the sun; the cause of which was soon found to be myriads of locusts, raised about twenty or thirty fathoms from the ground, and covering an extent of several leagues, upon which a shower of these insects fell, devouring while they rested themselves, and then resuming their flight. This cloud was brought by a very strong easterly wind; it was all the morning passing over the adjacent country, and it was supposed the same wind drove the locusts into the sea. They spread desolation wherever they came; after devouring the herbage, with the fruits and leaves of trees, they attacked even the buds and the very bark; they did not so much as spare the dry reeds with which the huts were thatched. Hasselquist in his Voyage to the Levant, says that “the inhabitants of Asia sometimes take the field against locusts with all the apparatus of war. The bashaw of Tripoli in Syria some years ago raised 4000 soldiers against these insects, and ordered those to be hanged who refused to go.” Amidst the numerous blessings our own favoured isle enjoys, what a happiness it is to be exempted from the ravages of these pernicious insects, as well as from the government of bashaws! In the year 1748 great numbers of the grylli migratorii were seen in London and its vicinity, but they were not productive of any mischief, and soon perished.
[166] These unpleasant domestics were scarcely observed in England previous to the fire of London in the year 1666. It is conjectured that they were afterwards introduced with the limber imported for re-building the houses: allowing this to be the fact, posterity may console themselves with the inconveniences they sustain from this evil, by reflecting how much benefit they have derived in other respects from the unhappy catastrophe which produced it.
These insects may be killed either with boiling water or a few drops of the etherial oil or spirit of turpentine. They are all of them to be stuck through the thorax or back, betwixt the shoulders; the wings of the grylli and some of the others are to be expanded, and kept so by the little braces, and their legs, antennæ, &c. placed in a natural situation.
THE METHOD OF COLLECTING INSECTS CALLED NEUROPTERA.
Those of this class, the fourth order of Linnæus, are chiefly aquatic, residing in the waters as caterpillars, and flying about them in their perfect state. The principal genera are, the libellula, dragon-fly; ephemera, may-fly; phryganea, spring-fly; hemerobius, and panorpa. The libellulæ are considered by the generality of people as containing in them something venomous; and from hence, in addition to the epithet, alone sufficiently tremendous, of dragon-fly, have obtained the several names of adder-spear, adder-bolt, horse-stinger, &c. It must be confessed, that their shape, manner of flight, &c. are such as might readily raise such an idea in the minds of the multitude, who but too often form their decisions from appearances only; but naturalists are unaccustomed to such hasty determinations, and they can safely advise the collector not to be misled by terrific words, nor intimidated from catching them, they being perfectly harmless, indeed more so than the gnats which constitute a part of their food. The butterfly net already described will be very convenient for catching insects of this order, particularly the libellulæ.
They are all of them easily killed, either by pressure of the thorax, or with spirit of turpentine, spirit of wine, or the fumes of sulphur; the same means are to be used in setting them as in the hemiptera.
THE METHOD OF COLLECTING INSECTS CALLED HYMENOPTERA.
The remarks which have just been made on the libellulæ do not apply to insects of this order, the major part of them being armed with stings; some of which are, however, harmless, though others are venomous. The principal genera are, the tenthredo, saw-fly; ichneumon, ichneumon-fly; sphex, ichneumon-wasp; vespa, wasp, hornet; apis, bee; formica, ant; sirex, and chrysis. The tenthredines are found on trees and flowers in their caterpillar state; they feed on the leaves of plants. The ichneumons are found in the same manner; in their caterpillar state, they live chiefly in the bodies of other insects, particularly in the caterpillars of the moths and butterflies, as has been already mentioned. The sphex resides principally in sand-banks, it is also caught on flowers, shrubs and fruits, and about hedges; this insect catches and kills others, which it buries in the sand, having previously deposited its eggs in them. Wasps, bees, and ants, are found on flowers and fruits, and almost on every sweet substance. The chrysis, of which many species are exceeding beautiful, is found flying about old walls, posts, sand-banks, &c. in which it builds its nest. Wasps and bees are the only winged insects that have any great degree of poison in them, they should therefore be taken with the forceps before described, and handled cautiously on account of their stings, which are dangerous. Some, as the mytilla, naked bee, have stings, but no poison, and are to be found on the flowers of umbelliferous plants, when the sun shines hot in the middle of the day; at which time others, as the chrysis, &c. are also to be met with: when caught, a pin is to be stuck through them whilst in the net. It is very difficult to kill these insects without injuring them in some respect; boiling water hurts their wings, and the fine hairs with which many of them are covered; spirits of wine or turpentine prove immediately fatal to some, whilst others are scarce affected by them; and letting them remain transfixed till they are dead, will probably be thought too cruel; it is said, that the best method hitherto practised, is to stick them through with a needle dipped in aqua fortis; the sphinges, and other large moths, are likewise killed in the same manner with the least injury: the reader will adopt either of these methods, or any other he may deem expedient. When dead, their wings are to be expanded, and kept in as natural a position as possible.