Page images
PDF
EPUB

I do not know anything definite about the early life history of B. bipunctata. It is clear that the larva described by Giraud (Ann. Soc. Ent. Fr. (4) viii., p. 55), refers to B. lineolata, while according to Dours (Cat. Syn. des Hymèn. de France, p. 18) "la larve vit sur les rosiers à basse tige," but this requires confirmation. I have taken it on the alder several times.

Mr D. C. Glen, F.G.S., in name of the Local Executive Committee of the British Association, presented to the Library copies of the several guide-books issued during the recent meeting in Glasgow. Mr Glen was requested to convey to the Committee the best thanks of the Society for this donation. It was also resolved to render the thanks of the Society to those of its members who had provided the collections of birds, insects, and sea-weeds, for the exhibition in the Queen's Rooms, which had been organised by the Zoological and Botanical sub-section of the Museum Committee of the British Association.

28TH NOVEMBER, 1876.

Mr James Barclay Murdoch, Vice-President, in the chair. Mr William Hamilton, Yokohama, Japan, was elected a corresponding member, and Messrs Rowley Jex Long, John F. Millar, and David Robertson, jun., ordinary members of the Society.

SPECIMENS EXHIBITED.

Mr Peter Cameron exhibited specimens (1) of Ceroptres cerri, Mayr, an inquiline gall insect, new to the British fauna, from the banks of the Clyde, near Newton. The occurrence of this species in this country is of interest, as on the Continent it frequents galls which have not been found here, these galls being attached to Quercus cerrus, which is not a British plant. (2) Mesoleius marginatus, Brischke, an ichneumon hitherto unrecorded as British. It was bred from larvae of Lophyrus pini, got in a wood at Lambhill. The ichneumon was first described from the neighbourhood of Königsberg. (3) There was also shown a specimen of the American gall-fly, Cynips spongifica, a species remarkable (as has been stated by Walsh), from its possessing

two very distinct forms, differing very considerably from each other; one form being met with in the spring, this brood occasionally producing males, although in the proportion of one or two males to hundreds of females; the second form occurring in the autumn, and exclusively composed of females. Without offering any opinion as to the other dimorphic form, Mr Cameron remarked that the specimen which he exhibited could not be placed in any of the modern genera, and that a new genus would require to be formed for its reception-this, indeed, having been already done by Reinhard, without that naturalist having seen the insect. He likewise stated his conviction that it was extremely doubtful if the two so-called dimorphic forms described by Walsh pertained to the same species.

PAPERS READ.

I. On the Asphondyliae of the Glasgow district. By Mr
FRANCIS G. BINNIE.

Those abnormal swellings and outgrowths found upon plants of all orders, and familiarly known as "galls," present one of the most interesting fields for study that it is possible to select. The majority of these diseased growths are the work of insects, among which two families stand pre-eminent as gall-makers—viz., the Cynipidae among the Hymenoptera, and the Cecidomyidae among the Diptera.

The productions and habits of the latter family-the Cecidomyidae, or Gall-midges-I have made it my object to investigate, and have already got together a considerable amount of material, which I trust may furnish matter for various papers before this Society, and which will probably embrace several new species.

I have selected the genus Asphondylia, not because I have much that is new to advance, but from the very interesting habits of the species composing it, and from the well-marked characters which distinguish it from the other genera of the family—viz., the absence of distinct whorls of hairs on the pubescent, cylindric, and sessile joints of the antennae. Some of the largest species of the group are to be found in this genus. The pupa is provided with two projecting tooth-like processes at its anterior end, to assist it in forcing its way through the tissues of the enclosing cell when about to assume the perfect state.

In the Glasgow district I have observed the following species:A. sarothamni, Lw.-This species is characterised by its size, and by having 15-jointed antennae in the male, 14-jointed in the female, with the terminal joint markedly shorter than the preceding one.

This species forms galls on the common broom (Cytisus scoparius, Link) of three well-defined kinds.

1. Axillary, and having the appearance of a large swollen bud. The gall is smooth, with indications of ribs, pointed at the apex, one-celled and thin-walled, length, 3-3 lines. It makes its appearance in early spring, each gall containing a single larva, which goes through its transformations within the gall, emerging by a somewhat ragged hole near the apex. The perfect insect begins to appear towards the end of May. This seems to be the form of gall described by Winnertz (Linnaea Entom., viii., 283), and Kaltenbach (Die Pflanzenfeinde, p. 107).

2. Also axillary, but usually crowded together in some numbers on the apical portions of the twigs. It is elongate and cylindric, length, 3-6 lines; open at the apex, which is usually two-lipped, from which a passage, filled with dense interlocking white hairs, leads into the thin-walled cell at the base, containing a single larva, one line and a quarter long, bright orange or reddish orange, and minutely tubercled. The gall makes its appearance at the end of summer, and continues through the autumn. The larva leaves the gall to pupate in the earth, the perfect insect emerging probably the following spring. I have never bred the imago from this gall, and feel somewhat doubtful whether it may be referred to A. sarothamni.

3. A galled pod. The part affected becomes inflated, is oval or round in shape, circular in transverse section, and projecting equally on both sides of pod. It is thin-walled, forming an internal cavity which contains a single larva, and the galled portion retains its green colour after the rest of the pod has become black. The perfect insect emerges by a hole in the side. The gall is found during the summer, and the present species has been bred from it by Mr Traill.

Gall No. 1 is pretty common, No. 2 is abundant, and both are generally distributed in the district. No. 3 I have seen only in one locality, near Milngavie, and have failed to find it elsewhere where No. 2 is abundant.

A. ulicis, Verr.-This species was first recorded and named by Mr J. W. H. Traill, M.A., F.L.S. (Scottish Naturalist,' ii., 172), and Mr Verrall afterwards gave a full description of the perfect insect from dried specimens (Ent. Mo. Mag., xi, 224).

It is readily distinguished from its congeners, by its 13-jointed antennae in both sexes, with the two apical joints globular and abruptly shorter than the preceding joint, which equals the two taken together. It is also a large species, having an alar expanse of 5 lines. According to Mr Verrall, the small transverse veinlet near the base of the wing is seemingly absent. I cannot see any indication of it in my specimens, but I might observe that Winnertz describes this veinlet in sarothamni as being very pale. In his description Mr Verrall omits to mention the two longitudinal furrows on the thorax. The species does not seem to be known on the Continent, being probably overlooked.

The gall is found on the furze (Ulex europaeus, L.), and consists of the two sepals of the flower, the inner whorls having entirely disappeared. It is somewhat inflated, but is not very noticeable until the flower is past, when, from retaining the form of an unopened flower-bud, it is very conspicuous. The larva goes through its transformations within the gall, and the perfect insect emerges in July and August by a hole near the apex, leaving the empty pupa case in the opening.

The pupa is at first uniform reddish-brown, paler beneath; afterwards, middle dorsal region of abdomen becomes darker, then head and thorax darker brown, dorsal portion of abdomen assuming a blackish shade; antennae, wing, and leg-cases appear almost jet-black. The thorax is glossy, with the exception of a medial dorsal line. There is no cocoon.

It seems generally distributed in the district, as I have taken it on the moors near Milngavie, on the Kilpatrick hills, and in Kilsyth glen.

A. pimpinellae, Lw.-I have observed inflated seeds in the umbels of Angelica sylvestris, L., at Mugdock Wood, which I have little doubt may be referred to this species. Mr Traill (Scot. Nat., i., 125) has recorded the ordinary gall of this species, which occurs on Pimpinella saxifraga, L.

A. genistae, Lw., which forms galls on Genista germanica, is a British species, but from its habitat need not be looked for in our

[blocks in formation]

district. Schiner (Fauna Austr. Dipt. ii., 396) suggests the probability of it being only a variety of A. sarothamni.

In these notes I have altogether disregarded five species given by Walker as British.

II.-Notes on Cecidomyia trifolii, Fr. Lw., and its Gall.
By Mr FRANCIS G. BINNIE.

The species was only described in 1874, by Dr Franz Loew (Verh. der K.K. Zool-bot Gesell. xxiv.), but the gall had previously been recorded for Britain by Mr J. W. H. Traill, M.A., F.L.S. (Scot. Nat. I., 195).

This species belongs to the genus Cecidomyia, as restricted by Loew; and the character of the antennae, stalked in the male and sessile in the female, places it in a sub-division of the genus whose members are extremely difficult to distinguish from one another. The habit of the larva, however, offers a ready means of distinction when correlated with other differences; and usually a good specific character is to be found in the number of the antennal joints. In the present species these are 14-15 in both sexes.

The gall is found on Trifolium repens, L., during the summer. It consists of a folded leaflet, a pseudo-cell being formed in the vicinity of the mid-rib, the walls of which become inflated and more or less fleshy, often tinged with red externally, and one, two, or all the leaflets of the triplet may be affected. Each leaflet is inhabited by 1-2 larvae; on one occasion 4 were found. They are white when young, and gradually change to orange at maturity, when they attain a length of three-fourths of a line. The insect generally goes through its changes within the gall, the larva spinning a white cocoon. About this time, however, numbers of the cells are to be found empty, from which, in the absence of any indications of the ravages of an enemy, it may be inferred that a certain number of the larvae descend to the earth to pupate.

The perfect insect begins to emerge towards the end of August, and at intervals for some time afterwards, and larvae, pupae, and imagos may all be found during that period. The galls occur commonly in the Possil district and near New Kilpatrick, and are probably generally distributed. I have never found this species affecting Trifolium pratense, for which Dr Loew records it. My observations on the economy of the species differ in some minor

« EelmineJätka »