two joints in the tarsi, with antennæ longer than the head, and composed of from six to ten filiform joints; whilst they differ from the Monomera by the winged individuals possessing four wings, the anterior being ordinarily of the same membranous texture as the posterior. The section consists of the families Psyllidæ, Aphidæ, and Aleyrodida; the genus Aleyrodes disagreeing so much from the Aphidæ, in which it is placed by Latreille, and from the Coccidæ, in which Burmeister arranges it, that I have thought it most natural to consider it as forming a distinct family. 12 13 15 Fig. 117. The family PSYLLIDA has long or moderately long filiform antennæ composed of ten joints, the basal one being thick, and terminated by two short seta (fig. 117. 1. Psylla -?, the largest British species); in Livia they are much shorter, with the second joint very greatly dilated; they are inserted in front of the eyes, at the sides of the head, which part of the body is deeply cleft in front; the eyes are lateral and prominent, the ocelli, three in number, placed in a triangle, the posterior ones close to the eyes (fig. 117. 2. head above); the promuscis is short, triarticulate, arising almost between the fore legs. (fig. 117. 3. head beneath), enclosing several very slender elongated setæ, capable of being thrust out to a great length, as in fig. 117. 6.; the thorax is of a very large size, the prothoracic collar is very short, the mesothorax and metathorax fully developed, the former composed of several parts (fig. 117. 1.), terminated by a small scutellum. Beneath, the epimera of the metathorax are singularly produced behind the place of insertion of the hind legs (which are pushed forwards), and terminated by two strong spurs (fig. 117. 5. body sideways); the tarsi are composed of two joints (fig. 117. 4. hind leg); the wings, which occur in both sexes, are deflexed at the sides of the body, the fore wings being of a firmer consistence than the hind wings, and furnished with three strong furcate nerves; the nerves of the hind wings are very delicate; the abdomen is small, and terminated in the females by a plurivalve conical ovipositor (fig. 117. 1.), and in the males by several erect appendages (fig. 117. 5.). The general habit of these insects is very similar to that of some of the Cicada, with which they also agree in their saltatorial powers and deflexed wings: hence, as well as from other circumstances, M. Dufour considers them intermediate between the Cicadellina and Aphides. They were named by Réaumur Faux Pucerons, from their relation to the Aphides; and by Linnæus, Chermes. Geoffroy, however, considering that the latter name had been improperly employed by Linnæus, gave to these insects the name of Psylla, from the Greek, in allusion to their saltatorial powers; whilst he employed the name of Chermes, in its more legitimate sense, to designate some of the Linnæan species of Coccus which had been employed as dyes, the names Chermes, Kermes, or Alkermes having been given by the Arabians and Persians to the Coccus llicis Linn., or famed Tyrian dye: Geoffroy's name has consequently received general adoption. They subsist in all their states upon plants, and have received specific names from the various trees and vegetables which they frequent. The species, however, require an attentive investigation, the majority being known only by their habitat, and not by any detailed specific description. Their larvæ (fig. 117. 8. larva P. Betulæ denuded) have the body very flat, the head broad, and the abdomen rounded behind; the tarsi are terminated by a small membranous vesicle with two ungues; the antennæ are stated by Dufour to consist of only one joint; the pupa (fig. 117. 9. pupa P. Betulæ) are distinguished by having four large and broad scales on the back, which are the rudimental wings. Many species in the preparatory stages are covered with a white cottony secretion (fig. 117. 7. larva P. Betula), and their excrement forms threads or masses of a gummy sucreous nature. Some species also, by puncturing vegetables, in order to suck the sap, occasion the production of gall-like monstrosities, especially upon the leaves and buds. Psylla Buxi, whose history is traced by Réaumur (Mém. tom. iii. pl. 29. f. 1. 16.), causes the terminal shoots and young leaves of the box tree to assume the appearance of buds. The same author has also represented the details of the history of the species which lives on the fig (tab. id. f. 17-24. P. Ficus Latr., L. Dufour, Geoffr. pl. 10. f. 2.); whilst De Geer has in like manner illustrated Ps. Pyri, Urtica, and Betulæ, the last of which in the larva state is densely enveloped in a cottony secretion. Two species, Psylla Pyri and Chermes Mali Schmidberger, are very injurious in orchards, the former to the young shoots and leaves of the pear, and the latter to the apple. The history of these two species is given in Kollar's Treatise on Insects injurious to Gardens, &c. translation, p. 275-284.; and some particulars relative to the pear Psylla were published by Mr. Knight in Hort. Trans. 2d series, vol. ii. p. 107.; and Gard. Mag. (Loudon) No. 92., Nov. 1837. Latreille has given us the history of a curious species, Livia Juncorum, which inhabits the common Juncus articulatus, depositing its eggs in the flowers, or at least in their shoots: the action of the sap produced a monstrosity in the diseased part, resembling a bundle of grass, within which the insects reside in their different states, supporting themselves on the juice of the plant, and emitting a white farinaceous excrementitious secretion, in the midst of which they delight to reside. (Bull. Soc. Philomat. tom. i., and Hist. Nat. Fourmis, p. 325.) Mr. Curtis has figured this insect (Brit. Ent. pl. 492.), and has stated that he detected three joints in the tarsi; the basal joint being, however, scarcely visible, except in the hind legs. The family APHIDE* comprises the very numerous and obnoxious species of plant lice (fig. 117. 10. Aphis Persica), a tribe of insects De la Hire. • BIBLIOGR. REFER. TO THE APHIDÆ. Obs. sur 1. Pucerons, in Mém. Acad. Sc. Paris, 1703. Bonnet. On Aphides, in his ŒŒuvres, tom. i. Richardson. Obs. on the Aphides of Linnæus, in Phil. Trans. 1771. Hausmann. Beitr. d. g. d. Blattlause, in Illiger. Magaz. zu Insekt. b. 2. 1802. Kyber. On ditto, in Germar's Magazin d. Ent. 1812. Dutrochet. Anat. Aphides, in Annales des Sci. Nat., Oct. 1833. Duvau. Nouv. Rech. sur l'Hist. n. de Pucérons, in Mém. Mus. d'Hist. Nat, tom. xiii. 1825, and Ann. Sc. Nat. tom. v. Kittel, in Ann. Soc. Linn. de Paris, tom. v. Boyer de Fonscolombe, in Ann. Soc. Ent. de France, tom. iii. (Phylloxera.) Haliday, in Annals of Natural History, Nov. 1838. Ferussac. Puceron de Therebinth, A. Pistaciæ, in Nouv. Bull. de Sci. tom. iii.; and in Bull. Soc. Phil., 1812, 1813. Macquart. Puceron du Blé, in Ann. Sci. Nat., April 1881. analogous, in regard to the vegetable world, to the animal parasites of the order Anoplura, or lice; and which, from their constant occurrence in great numbers upon almost every species of plant, must have attracted the attention of every observer: from the Psyllidæ they are at once distinguished by their antennæ being only 7-jointed; from the Aleyrodidæ by the more numerous veining of their wings. The rostrum is more or less perpendicular or inflexed, varying in length, being in some species nearly half as long as the body, and consists of four joints (fig. 117. 12 head of Cinara Pini? Curt.). Latreille describes the labium as 3-jointed, and Curtis as 5-jointed; the terminal joint described by the latter appears to me to be the exserted tips of the enclosed setæ; the labrum is long and pointed at tip; the antennæ are of moderate or great length, and consist of seven joints, the last being sometimes obsolete, and the third the longest. The ocelli, three in number, form a large triangle; the eyes are entire, prominent and semiglobose. The thorax is oval, with the prothorax forming a transverse collar; the abdomen is short and convex, ovate or elongateovate, soft, and generally furnished with a more or less elongated tubercle on each side near the extremity. The wings are very much deflexed at the sides of the body, being almost perpendicular in repose (fig. 117. 11.); the fore wings much larger than the posterior, with strong nerves, the subcostal nerve terminating in an elongated stigma, close to which runs another longitudinal nerve, obliquely emitting two or three straight nerves, which run to the hind margin of the wing, the last of which emits one or two branches; the posterior wings have two similar oblique nerves. The legs are long, or very long and slender, formed only for crawling; the tarsi short and 2-jointed, the basal joint being shortest (fig. 117. 13.). The pupa state is active, and resembles the imago, except in possessing rudiments of wings upon the back (fig. 117. 15. Pupa Aphis Blot. (Myzoxyle) in Mém. Soc. Linn. Calvados. Bonafous. Aphis Zeæ, Ann. Soc. Ent. France, 1835. Walker, in Entomol. Mag. No. 14. Schrank, in Fauna Boica. Van Heyden, in Museum Seckenbergianum, b. 2. 1837. Morrem, in Annales Sc. Nat., August 1836. Anat. Aph. Persica. And the general works of Réaumur, De Geer, Linnæus, Frisch, Curtis, Latreille, Harris (Exposition of Eng. Ins.). Pruni), at least in those individuals which ultimately acquire wings; but the family is very anomalous in this respect, many specimens (indeed the majority) never acquiring wings (in which case the pupa is not to be distinguished from the mature larva or imago states), although at certain seasons of the year other individuals of the same species, and of both sexes, obtain fully developed wings. It is also to be observed, that it is chiefly the females which are produced in this imperfect condition (fig. 117. 14. Aphis Rosæ ?); and when we consider that these individuals are placed in the midst of an ample supply of food both for themselves and their numerous progeny, we cannot be surprised at the non-production of organs which would be comparatively useless; whilst, at the same time, it is not unworthy of remark, that the loss of these organs is accompanied by an extraordinary development of the ovaries: moreover, the suddenness of the maturity of these apterous specimens, dependent upon the object of their production, namely, the checking of vegetation, at such time in the most luxuriant state, seems sufficient to account for the non-production of wings, which would require a greater period of time for their development. The species reside in great societies upon almost every species of plant, of which they suck the juices of the young shoots, leaves, stems, and even roots †, by the assistance of their proboscis, producing in many instances disease in the plant either by greatly weakening it, or by distorting young shoots and leaves; some species raising vesicles, or other gall-like excrescences, in which whole. generations of Aphides are residents. The anal tubercles above-mentioned (which are wanting in some species), secrete a saccharine fluid of which ants are very fond; and it is this fluid dropped upon the adjacent leaves, or the extravasated sap flowing from the wounds We have already seen in the Orthoptera and Fulgoride, that analogous instances occur, in which, however, rudiments of wings (quite unlike those of the true pupa) are acquired by some specimens, whilst others of the same species have them of full size; with the example of the Aphides in view, we can but be surprised that there should be entomologists who doubt the specific and even the generic identity of such individuals. See further observations hereon under Hydrometrida. A writer in the Entomol. Magazine, No. 14. p. 337., states that he found whole troops of Aphides in the pips of large sound codling apples! The same writer has published ample details of the injuries committed by Aphis Humuli upon the crops of hops in the same work (No. 3. p. 217.), in which (No. 3. p. 315.) another observer has stated that he has observed the hop-fly produce young actually provided with wings! |