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different parts of the world; one only of which is found in Great Britain.
THE COMMON GLOW-WORM *.
During the summer season these insects are observed after sun-set, in meadows, by road sides, and near bushes. Among the crooked lanes, in every hedge, the Glow-worm lights his gem, and
through the dark
A moving radiance twinkles.
They are chiefly to be seen during the month of June. In the day-time they conceal themselves amongst the leaves of plants.
Each sex is luminous, but in the male the light is less brilliant than in the female, and is confined to four points, two of which are situated on each side of the two last rings of the abdomen. The utility of the bright light of the females is supposed to consist in attracting the attention of the males during the dark, when, only, they are able to render themselves conspicuous. They always become much more lucid when they put themselves in motion. This would seem to indicate that their light is owing to their respiration; in which process, it is probable, phosphoric acid is produced by the combination of oxygen gas with some part of the blood, and that a light is given out through their transparent
*See Plate xviii. Fig. 4, 5.
DESCRIPTION. The male Glow-worm is smaller than the female their heads are of the same shape, and equally concealed by the plate of the thorax. The principal difference between the sexes consists in the abdomen of the male being covered with brown wing-cases, shagreened, and marked longitudinally with two lines: these are longer than the abdomen. The female is destitute of wings.
SYNONYMS. Lampyris noctiluca. Linn.-Lampyre lumi
bodies by this slow internal combustion. By contract ing themselves, the insects have a power of entirely withdrawing it: when they are at rest, very little light is to be seen. M. Templer, who made many observations on these insects, says that he never saw a Glowworm exhibit its light at all, without some sensible motion either in its body or legs. This gentleman; when the light was most brilliant, fancied that it emitted a sensible heat.
If the insect be crushed, and the hands or face be rubbed with it, they contract a luminous appearance, similar to that produced from phosphorus. When a Glow-worm is put into a phial, and the phial is immersed in water, a very beautiful irradiation will be found to take place.
The female glow-worms lay a great number of eggs on the turf or plants on which they live. These eggs are somewhat large for the size of the insects, of a round shape, and lemon colour. When first deposited, they are covered with a yellow, viscous matter, which serves to fix them to the plant.
When full grown the larvæ are about an inch long, and so nearly resemble the females in appearance, that it is a difficult matter to distinguish the sexes. When they change to their pupa state, the skin generally splits on the middle of the head and back, and leaves an opening sufficient to give passage to the whole body..
As soon as the larva is completely disengaged from the skin, it curves its body into an arc, and is then in a It still has much resemblance to the larva. pupa state. The only indication of life now, is its curvature, from time to time, downwards, and its moving occasionally from side to side.
OF THE ELATER OR SKIPPER TRIBE*. The Elaters fly with great facility, and when thrown
The antennæ are filaform, and for the most part serrated.
upon their backs, they are able to recover their position without using their feet: for this purpose the tho rax terminates in a strong, elastic spine, which is placed in a cavity of the abdomen. The insects, when upon their back, raise up the middle part of their body, so as to leave only the head and tail in contact with the plane on which they lie. The spine of the thorax is by this motion brought considerably out of its lodgment, and made to press against the side. Being from this position again slipped into its groove, with all the force the creatures are able to exert, the thorax and abdomen come together with so sudden a jerk, as to raise the body from the plane, and enable them to spring round.
The larvæ live and undergo their changes in the trunks of decayed trees.
THE NIGHT-SHINING SKIPPER*.
In the savannahs of most of the warmer parts of America, these insects are to be seen in great numbers, and also about the woods of several of the West India islands.
They are extremely luminous in the dark, the light proceeding chiefly from four parts; namely, from two glandular spots behind the eyes, and one under each wing. But they have the property of interrupting this light at pleasure, when these glandular spots become
The under part of the thorax terminates in an elastic spine, placed in the cavity of the abdomen.
*See Plate xviii. Fig. 2.
DESCRIPTION. This insect is of an oblong form, and an inch or upwards in length. It is so strong, and exerts such elastic powers, as, when placed on its back, sometimes to spring to the height of four or five inches in recovering its natural position. Its colour is brown, except the head, which is small and blackish.
SYNONYMS. Elater noctilucus. Linn.-Larger Fire-fly. Brown. Flies shining like Glow-worms. Purchas.
perfectly opake. When the rings of the abdomen are forced a little asunder, the same luminous appearance will be seen to issue indiscriminately from every part of their interior.
A person may with great ease read the smallest print by the light of one of these insects held between the fingers, and gradually moved along the lines, with the luminous spots above the letters: but if eight or ten of them be put into a phial, the light will be sufficiently great to admit of writing by it. Oviedo says, that the Indians travel in the night with them fixed to their feet and hands; and that they spin, weave, paint, dance, &c. by their light. He also conjectures, that " a marvellous water would come from them if distilled!"
They are seldom to be seen abroad during the day, for, except in the night, they are so inanimate, as even scarcely to exhibit any signs of life. The Indians principally value them from their hunting and devouring the musquitoes in their habitations, which would become otherwise excessively troublesome. They catch them in the night, by holding up a torch on some eminence, to the light of which the insects soon come, when they are beaten down with the branches of trees; or sometimes one of them is held up in the fingers and moved about, which will attract to the place such as are near, when they are either knocked down or seized with the hand.
The use of their light, as in the glow-worms, seems to consist in discovering the sexes to each other.
OF THE DYTISCUS OR WATER-BEETLE TRIBE*.
The bodies of these insects are admirably formed for passing through the water with as little impediment as possible, being nearly boat-shaped, and on the surface
The antennæ are setaceous. The sturnum is cleft; and the body oval, and keel-shaped beneath. The hind legs are fringed on the inner sides, and formed for swimming.
perfectly smooth. They inhabit ponds and ditches, but occasionally fly in search of other waters. The males are distinguished from the females, by having a horny concave flap or shield on the fore-legs. The hindlegs in both sexes are peculiarly adapted for the aquatic residence of the insects, being furnished on the inner sides with a series of long and close-set filaments, so as somewhat to resemble fins. In the large species, the elytra or wing-cases of the males are smooth, and those of the females furrowed.
The larvæ are extremely voracious, feeding on other aquatic insects, on worms, and even on young fish. They continue in this state about two years and a half; and when about to change into pupa, they form a convenient cell, and secrete themselves for the purpose in the banks or amongst the weeds.
THE MARGINED WATER-BEETLE
Although water is the principal element in which these insects reside, they are perfectly amphibious. They may occasionally be found in all fresh waters; but are most frequently seen either in such as are stagnant, or where the stream is extremely slow.
They are predatory and very voracious, devouring, in great numbers, not only other water-insects, but also those of the land. They seize their prey in their forelegs, and with these carry it to their mouth. Although they are able to continue immersed for a great length of time, yet it is necessary for them to rise occasionally to the surface of the water, in order to breathe. They
DESCRIPTION The body is black. The edges of the thorax, and the outer margins of the wing-cases, are yellow. The wing-cases of the females have numerous longitudinal grooves. Linn.-Le Dytisque
SYNONYMS. Dytiscus marginalis. bordé. Cuvier.