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MODERN CLASSIFICATION

OF

INSECTS.

ORDER THYSANOPTERA Haliday.*

(Genus Thrips Linn.)

CHAR. Wings 4, alike, long, narrow, membranous, neither folded nor reticulated, with long ciliæ, laid horizontally along the back when

at rest.

Mouth with two setiform mandibles; two triangular flat palpigerous (but not galeated) maxillæ, and a palpigerous labium.

Tarsi, with two joints, vesiculose at the tip.

Pupa active, semi-complete.

The insects of this order (fig. 57. 1. Phlæothrips coriacea Hal.?)

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are of a very minute size, rarely exceeding a line in length; the body is long, linear, and depressed; the head (fig. 57. 2. upper side) is

BIBLIOGR. REFER. TO THE THYSANOPTERA. (THRIPIDE.)

Haliday, in Entomol. Mag. vol. iii. and iv.

Schrank. Beitrage zur Naturgesch. 1776. Leipz.

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oblong, narrower than thorax, without any distinct neck; the eyes are large, coarsely granulated, and occupy its anterior lateral angles, besides which, there are ordinarily three ocelli between the eyes, and behind the antennæ; the underside of the head (fig. 57. 3.) is prolonged into a kind of conical beak, which extends beneath the prosternum; the antennæ (fig. 57. 7. and 57. 15. T. fasciata) are longer than the head, filiform, and apparently varying in the number of joints from five to nine, in consequence of the terminal joints being more or less firmly soldered together; they are inserted in front of the head. The parts of the mouth, although constructed in the mandibulated and palpigerous form, unite into a short conical sucker, which does not extend beyond the anterior coxæ. The clypeus and labrum occupy the anterior part, the latter being linear-subconical, beneath the base of which arise a pair of horny setiform mandibles (fig. 57. 4.), of which the base is dilated into a flattened plate in the species I have dissected. (Mr. Haliday described them as having a bulbous base, and, by their junction towards the tip, as forming a 2-valved syphon.) The maxillæ (fig. 57. 5. and 57. 13. T. fasciata) are flat, elongate-triangular, and pointed at the tip, without any apparent articulation, and with a 2 or 3-jointed palpus, arising on the outer edge near the middle; there is no appearance of an outer lobe or galea. The labium (fig. 57. 6.) is submembranaceous, and more or less attenuated in front; in some species the mentum is very distinct, and the labium is extended in front, between, and of equal length with, the palpi*; but in T. fasciata (fig. 57. 14.) I could not perceive it to be prolonged beyond the base of those organs; the labial palpi are very short, and 2 or 3-jointed.

De Geer was the first author who noticed the existence of palpi in these insects. Latreille, also, described the maxillary pair, but regarded the labial palpi as articulated lacinia. He, moreover, overlooked the mandibles which were first observed by Strauss, who communicated the discovery to Latreille (Fam. Nat. p. 416.), who, however, seems to have been inclined to doubt their right to such a title, although admitting that, if they were really mandibles, they would form a very peculiar family in the order Orthoptera; although

"Rostri vagina (including the maxilla and labium), submembranacea ad basin lata et utrinque uni-palpigera (scil. the maxillary palpi), apice profunde trifida; laciniis æque longis, media acuta; externis (scil. the labial palpi), sublinearibus triarticulatis; palpi (maxillary), brevissimi filiformes," &c. Latr. Gen.

3. 171.

"l'ensemble de leur organisation' Homoptera than the Orthoptera.*

appeared more allied to the

The figures given above are the first which have yet been published of the parts of the mouth in detail of these curious insects.

The prothorax is large, depressed, and more or less narrowed in front, its hind part being broader than the head; the meso- and metathorax are large, flat, and closely soldered together, the former being often the shorter, and transverse; the meso-scutellum is not a conspicuous piece; the four wings are nearly alike, the anterior pair (fig. 57. 11.) being rather larger than the posterior (fig. 57.12.); they are ordinarily narrow, membranous, and without nerves, crossing and resting horizontally upon the back, and furnished with long and delicate ciliæ, extending all round the wings. In some species, however, Mr. Haliday describes the fore-wings as transformed into broadish elytra, ciliated only behind, and with longitudinal and transverse nerves. In some species the wings are wanting, at least in the males; the abdomen is terminated either by a long attenuated joint or by a 4-valved borer in the female; the legs are short, the anterior pair having the femora sometimes much incrassated, with a tooth near the inner extremity (fig. 57. 8.); the tibiæ are simple, the tarsi 2-jointed, terminated by a vesicle without ungues; the base of the anterior tarsi is, in some species, armed with a tooth, at least in the males; the middle (fig. 57. 9.) and posterior pair of legs (fig. 57. 10.) are simple. My figures, 57. 1-12., are taken from the largest species of the order which I have seen, and of which I captured a considerable number, creeping under and upon the bark of felled trees, at Sèvres, in July, 1837. It appears to be nearly allied to Phlæothrips coriacea Hal.

The eggs of Phlæothrips statices Hal. "are shaped like those of Culex, being cylindric, rounded at one end, and crowned with a knob at the other." The larva (fig. 57. 16., from De Geer) is equally active with the imago inhabiting the same situations, and differing in smaller size, softer body, distinct thoracic segments; "the mouth is almost alike, the antennæ and legs shorter; there are no simple eyes, and the comIf regarded as Mandibulata (although they are certainly not Dacnostomatous), they will possess the greatest affinity with those Biomorphotic insects which have equal sized unfolded wings, and which will be found amongst the earlier families of Neuroptera, especially the Termitidæ.

+ De Geer observes, that, when the animal presses this vesicle on the surface upon which it walks, its diameter is increased, and it sometimes appears concave, the concavity being in proportion to the pressure, which made him suspect that it acted like a cupping-glass.

pound eyes are replaced by conglomerate eyes; the pupa (fig. 57. 17., from De Geer) resembles the perfect insect, but the articulation of the limbs is obscured by a film, and the wings enclosed in short fixed sheaths. The antennæ are turned back on the head, and the insect, though it moves about, is much more sluggish than in the other states." (Haliday, Ent. Mag. 15. p. 440.) The larvae are generally much paler coloured than the imago, being in some species blood red, whilst the imago is black; in others, pale yellow.

These insects are found upon various plants, sometimes swarming in immense profusion in various kinds of flowers, especially the large white hedge-convolvulus; they are very agile, and often leap to a considerable distance when disturbed. They feed upon the juices of plants, and are often extremely injurious, especially in hot-houses and vinehouses; the leaves upon which they reside being marked all over with small decayed patches. They also, especially, infest melons, cucumbers, kidney beans, &c. Various plans for their extirpation are given in the Gardener's Magazine, and in Major's work on the insects which infest fruit trees.

One species, to which Mr. Haliday has applied the specific name of Thrips cerealium, infests the wheat, sometimes to a mischievous extent. This species was observed by Mr. Kirby, between the internal valve of the corolla and the grain, and taking its station in the furrow of the seed, in the bottom of which it seems to fix its rostrum, and by depriving it of its moisture, occasions it to shrink up, and become what the farmers call pungled. One sex of this species is apterous; the larva is yellow and very nimble, and the pupa whitish, with black eyes, and very slow and sluggish. (Linn. Trans. vol. iii. p. 247.)

According to Vassalli Eandi (quoted by Mr. Haliday), this species also gnaws the stems above the knots, and causes the abortion of the ear. In the year 1805, one third of the wheat crop in Piedmont is said to have been destroyed by this minute insect; and in the same year the wheat crops in England suffered materially from a similar

cause.

Another species is very injurious to the olive tree in the territory of Pietro Santa in Tuscany, fixing itself on the under side of the leaves. As early as the month of April, four or five eggs are deposited on each bud; and, as the generations of the insect succeed from spring to the end of autumn, the number of insects becomes inconceivable. (Passerini, "Alcune notizie sopra una specie d'Insetto

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