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THE PARAPLECTIC WEEVIL*.
This insect has been in some measure rendered famous by the remarks of Linnæus, who believed that to it ought to be attributed the cause of the disease in horses, called the staggers. The larvæ of the Paraplectic Weevil inhabit the interior part of the stems of an umbelliferous plant, the phellandrium aquaticum, which grows in vast quantities in marshes and other watery places. Horses that have eaten of this plant, have been known to have this disease. Linnæus asserts, that it is not the plant which causes it, but the larvæ of these insects; since it has been remarked, that such plants as were not infested with them, had been eaten by the animals without injury.
In order to find the larvæ, the stem must be slit from top to bottom. The little creatures choose for their dwelling only that portion of the stem which is submerged. They feed, with their heads always upwards, on the substance or pith with which they are surrounded. Each stem contains only a single insect. The larvæ are each about seven lines in length, and somewhat more than a line in diameter. Their bodies are composed of twelve annules, which have transverse wrinkles on the back. The body is of a yellowish white colour, and the head brownish.
They undergo their transformations within the plants. On opening a stem towards the end of July, the larva will be found to have undergone its change into a pupa state, without any other case to shelter it from injury, than that which the plant itself affords. In the pupa all the parts of the perfect insect are very distinct. Its
* DESCRIPTION. The body of this insect is cylindrical. It is black, but covered with short cinereous hairs. The wingcases are pointed.
SYNONYMS. Curculio paraplecticus. Linn.-Le Charançon paraplectique. Tigny.
only motion is in the abdomen; and, aided by this, it is able to pass along the cavity of the stem from one end to the other, applying for this purpose, against the parietes of the plant, the points of the abdomen, and the rows of bristles on the back.
Before the end of July these insects assume their perfect form; and, in this state, issue into day through a large oval opening, which they form with their mandibles or jaws, in that part of the stem which is above the surface of the water. These insects do not, as Linnæus has asserted, continue during the winter within the plants.
THE DOCK WEEVIL*.
On the leaves and flowers of some of the species of Dock, or Rumex, the larvæ of these insects are occasionally very numerous. They are usually found from the commencement of spring, until Midsummer. They are about three lines in length, and have a black and shining head. The three first rings of the body are black above, yellow on the sides, and greenish below. There is on each ring, beneath the body, a pair of fleshy teats, which supply the place of feet in walking. The under part of the body is also supplied with a viscous matter, by which they are enabled to hold themselves firmly fixed to the stems and leaves of plants.
In order to undergo their transformation into the pupa state, they spin a nidus, either on the stems of the plants which they inhabit, or amongst the flowers at the summit of the stem. This nidus is spherical, about
DESCRIPTION. The whole body is black, covered with cinereous hairs. The wing-cases are dark, varied with cinereous. The antennæ are brown at the base, and black at the extremity.
SYNONYMS. Curculio rumicis. Linnæus.-Le Charanzon de l'Oseille. Tigny.
the size of a pea, and very beautiful. It is composed of a yellowish or whitish silk, woven with meshes, and appears not unlike a sphere of the finest gauze, having the insect perfectly visible within it. In spinning this, the larva holds its body curved in a somewhat semicircular shape, by which the round shape of the nidus is obtained; its own body serving as the mould. A few days after this is completed, the insect changes to a pupa of a black colour. In this state it continues about twelve days, and then undergoes its final transformation.
OF THE CERAMBIX OR CAPRICORN TRIBE*.
The insects of the present tribe are among the most beautiful that are known. Their antennæ are frequently longer than the body. Many of the species diffuse a strong smell, perceptible at a great distance; and some of them, when seized, emit a sort of cry, produced by the friction of the thorax on the upper part of the abdomen and wing-cases.
Their larvæ are found in the inner parts of trees, through which they bore, feeding on and pulverizing the substance of the wood. They are transformed into perfect insects in the cavities they thus make, and never issue from their retreats till they have attained their perfect state.
THE TIMBER CAPRICORN t.
Both in its perfect and in its larva state this insect
* The antennæ of the Cerambyces are tapering and articulated. The thorax has several prominences; and the wingcases are long and narrow. To the mouth there are four palpi, or feelers.
+ DESCRIPTION. The body of this insect is of a dark violet colour, somewhat hairy and punctured. The thorax is rounded and downy; and the antennæ are nearly as long as
feeds principally on fir timber, which has been felled some time, without having had the bark stripped off. The circumstance of its attacking only such timber as has not been stript of its bark, ought to be attended to by all persons who have any concern in this article; for the bark is a temptation not only to this but to various other insects; and much of the injury done in timber might be prevented, if the trees were all barked as soon as they were felled.
The female is furnished at the posterior extremity of her body with a flat, retractile tube. This she inserts between the bark and the wood, to the depth of about a quarter of an inch, and there deposits a single egg.
By stripping off the bark, it is easy to trace the whole progress of the larva, from the spot where it is hatched, to that where it attains its full size. It first proceeds in a serpentine direction, filling the place which it leaves with its excrement, resembling sawdust, and so stopping all ingress to enemies from without. When it has arrived at its utmost dimensions, it does not confine itself to one direction, but works in a kind of labyrinth, eating backwards and forwards; which gives the wood under the bark a very irregular surface: by this means its paths are rendered of considerable width. The bed of its paths exhibits, when closely examined, a curious appearance, occasioned by the erosions of its jaws, which excavate an infinity of little ramified canals. When the insect is about to assume its pupa state, it bores down obliquely into the solid wood, to the depth sometimes of three inches, and seldom, if
the body. The wing-cases are narrow, rounded at the tip, and bulging towards the base. The head and thorax are sometimes greenish. The body is from four lines and a half to seven and half in length. Linnæus.-Callidium
SYNONYMS. Cerambyx violaceus. violaceum. Fabricius.
ever, less than two. These holes are nearly semi-cylindrical, expressing exactly the form of the grub.
At first sight, one would wonder how so small, and seemingly so weak an animal, could have strength to excavate so deep a mine; but when we examine its jaws, our wonder ceases: these are large, thick, and solid sections of a cone, divided longitudinally, which, in the act of mastication, apply to each other the whole of their interior plane surface; so that they grind the insect's food like a pair of millstones.
Some of the larvæ are hatched in October; and it is supposed that about the beginning of March they assume their pupa state. At the place in the bark, opposite to the hole from whence they descended into the wood, the perfect insects gnaw their way out, which generally takes place betwixt the middle of May and the middle of June.
These insects are supposed to fly only in the night, but during the day they may be generally found resting on the wood from whence they were disclosed.
The larvæ are destitute of feet, pale, folded, somewhat hairy, convex above, and divided into thirteen segments. Their head is large and convex.
OF THE LAMPYRIS OR GLOW-WORM TRIBE*.
The name of this insect is derived from the luminous appearance of the posterior part of its abdomen. The males are all winged, but most of the females are destitute of wings. In some of the species the males are not luminous. The larvæ, which feed chiefly on plants and leaves, nearly resemble the females in appearance.
There are about sixty known species, inhabitants of
* The antennæ are thread-shaped. The thorax is plain, somewhat orbicular, and conceals the head. The segments of the abdomen terminate in folded papillæ.