Chapter XX: Section 1: Solitary (3)

From the extreme rarity of the insect, I have been unable to examine the cibarial apparatus, and thence to ascertain upon what substantial grounds the generic distinctions are based, which separate it from _Osmia_. Whether it was these mere habits of the insect which induced Le Pelletier de St. Fargeau to establish the genus I do not know, but he is always extremely slovenly, and therefore very unsatisfactory in his characteristics, which are never framed in a strictly explicit manner. In consequence of all these difficulties, I have merely been able under the generic character to introduce such as he has given, which I could not derive from the personal external inspection of Mr. Desvignes’ female (my own selection of whose bees for the purposes of this work he has been so kind as to lend me, and whom I thus publicly present with my best thanks). I have therefore compounded a character as well as I could from St. Fargeau’s descriptions, inserted in the tenth volume of the ‘_Encyclopédie Méthodique_,’ and from his work on the _Hymenoptera_, forming one of the ‘_Suites à Buffon_.’

The habits of these bees, as said above, are to excavate vertical cylinders in hard down-trodden pathways and roads, by the sides of fields where corn is grown, and where consequently the common red poppy is abundant. From the petals of the flowers of this plant they cut out semicircular pieces, precisely as is done by _Megachile_ with the more rigid leaves of shrubs and trees, and convey them home and line their nests with them, just as is practised by that genus with those leaves,—with this difference merely, that a sufficient portion of the upper edge of the pieces of the petals used is left projecting, for the purpose of forming a covercle to the nidus, and which, when filled with provender and the egg deposited, is refolded over it and covered in, and it is closed up with earth. They then proceed to make another excavation, which is treated in the same manner, for they deposit only one larva in a tube. If disturbed in their retreat, they will show themselves at its mouth, like _Dasypoda_, to see what is the matter.

I would urge our collecting entomologists, especially those who have the opportunity of hunting up the west of England, to use due diligence and strive to confirm the native existence of this bee and add specimens to the cabinets of their fellow-entomologists.

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Genus 24. OSMIA, _Latreille_.
(Plate XIV. figs. 1 and 3 ♂♀.)
APIS ** _c_ 2 _δ_, Kirby.

_Gen. Char._: HEAD subglobose, concave, posteriorly fitting the prothorax and about as wide as the thorax; _ocelli_ placed far forward on the vertex, which is wide and convex, in a curved line; _antennæ_ filiform, sometimes subclavate, short, and geniculated, the _scape_ robust, as long as the four following joints, the basal joint of the _flagellum_ globose, its second joint clavate and as long as the terminal one, the remainder short, subequal, and gradually but slightly increasing in length; the _face_ flattish; the _clypeus_ a truncated triangle, convex; _labrum_ longitudinally oblong, a little laterally distended at the articulation, from whence the sides are parallel; _mandibles_ broad at the apex, obscurely tridentate, the internal teeth obtuse and short; _cibarial apparatus_ long; the _tongue_ three times the length of the labium, clothed with short hair and tapering from the base to the acute apex; _paraglossæ_ very short, coadunate at the base and acuminate at the apex; _labial palpi_ more than half the length of the tongue, the two first joints membranous and long, the basal one the broadest, seated on a petiole and not so long as the second, which tapers to an acute point, before the apex of which the remaining two short subclavate conterminous joints articulate; _labium_ about one-third the length of the tongue, acutely produced in the centre of its inosculation; _maxillæ_ as long as the tongue, subhastate and acuminate; _maxillary palpi_ four-jointed, rather short, the joints subequal and subclavate, but the second is both the most robust and slightly the longest. THORAX oval or globose; _prothorax_ inconspicuous; _scutellum_ lunulate and convex; _post-scutellum_ transverse and linear; the _metathorax_ abruptly truncated; _wings_ with two submarginal cells, and a third distinctly commenced, the second the longest, and receiving both the recurrent nervures, the first towards its centre and the second near its termination; _legs_ moderate, setose, the plantæ of all with a dense brush beneath; _claw-joint_ longer than the three preceding; _claws_ simple. ABDOMEN short, cylindrical, convex, the terminal segment slightly pointed, the ventral segments densely pilose in parallel lines from the second.

The MALE differs in having the _antennæ_ longer and always filiform, the ventral segments very concave, and the terminal dorsal segment variously mucronated, tuberculated, spinose or serrated, and the claws bifid.

NATIVE SPECIES.

1. _leucomelana_, Kirby, ♂♀. 3-4½ lines. (Plate XIV. fig. 3 ♂♀.)
2. _spinulosa_, Kirby, ♂♀. 3-4 lines.
3. _pilicornis_, Bainbridge, MS., ♂♀. 4-4½ lines.
4. _bicolor_, Schrank, ♂♀. 4-5 lines. (Plate XIV. fig. 1 ♂♀.)
5. _fulviventris_, Panzer, ♂♀. 4-5 lines.
_Leaiana_, Kirby.
6. _ænea_, Linnæus, ♂♀. 3-4½ lines.
_cærulescens_, Linnæus, ♀.
_cærulescens_, Kirby, ♀.
7. _parietina_, Curtis, [V. 222.] ♂♀. 3-4 lines.
8. _xanthomelana_, Kirby, ♂♀. 4-7 lines.
_atricapilla_, Curtis, [V. 222.] ♀.
9. _aurulenta_, Panzer, ♂♀. 4-6 lines.
_tunensis_, Kirby.
10. _rufa_, Linnæus, ♂♀. 3-6 lines.
_bicornis_, Linnæus.
_bicornis_, Kirby.

GENERAL OBSERVATIONS.

Named from _ὀσμὴ_, _sweet-scent_, from some fancied idea of their possessing the property of emitting a sweet odour; but this, although it is the case with many of the bees,—for instance, with the genera _Prosopis_, _Halictus_, _Nomada_, some of the _Anthophoræ_, _Saropoda_, and the male _Bombi_ and _Apathi_,—I have not noticed in any of this subsection, the _Dasygasters_, and therefore not in any of the present genus. It is possible that when richly laden with pollen, this may emit some smell, but I am not aware that any of the scent of flowers lies in the anthers or their pollen, although this in some cases has a spermatic odour pointing to its express function; but be this as it may, such is their name. These as a group are what are called the ‘Mason Bees,’ from the habit they have of agglutinating particles of sand or earth mixed with minute pebbles, scarcely larger than grains of sand, or raspings of wood combined in the same manner, with a secretion which they emit, and of which they form their cells. The instinct of the creature prompts it to be speedy in the operation, as the material, like plaster of Paris, dries very rapidly to a hard substance. Whether they have the power of softening the edges as the manufacture of the cell proceeds is not known, nor whether, as they add the material, it instantaneously consolidates itself, but the colour of the structures themselves would indicate a simultaneous mixture. This could not be the case, if the mortar or mixture were formed away from the domicile and brought home in little pellets, each being added upon the insects’ arrival, although they obtain it all from the same spot, whence arises its uniformity in colour, and they are speedy in the formation of their nests. These cells are rather rough externally, according to the nature of the material of which they are composed, but they are very smooth within. The nature of the cells varies with the places of their deposit, which is dependent upon the idiosyncrasy of the species. Thus, those which construct their cells in wood, form them of moistened particles of wood, and those which make them in cavities of any kind, in the earth, beneath stones, or within empty snail-shells, make a mortar of earth and sand and small pebbles. Some are strictly uniform in the selection of the material wherein they build, but others are perfectly indifferent to its locality, and adopt either earth or wood, and sometimes the mortar of walls, sandbanks or chalk cliffs. According to the nature or the size of the receptacle which they select, is the adjustment of these cells. Where the cavity is restricted they place them end to end, but where it is more roomy they affix them side to side, completely adapting themselves to the circumstances of the locality as I shall instance below, in the description of the special habits of the more conspicuous species. I have elsewhere referred to the metallic colouring of many of the species of this genus, and amongst them is found the greatest sexual disparity of personal appearance, the _O. leucomelana_, and one or two of the neighbouring species being, perhaps, the only ones wherein uniformity of appearance would unite the partners together. The majority are very pubescent insects, and the females of the terminal species in the foregoing list are remarkable for a couple of inwardly curved horns, springing from the base of the clypeus just below the insertion of the antennæ, an appendage usually a male attribute.

There is very great dissimilarity in the habits of the various species, whence no single characteristic will embrace them, nor is there any distinctive feature whereby the genus might bear subdivision, either from habits or habit, as will be collected from the following cursory survey of their special natural history.

Thus the first species, the _O. leucomelana_, named so from the white decumbent down which edges the black segments of the abdomen, extracts the pith from bramble sticks, and its cells are formed and closed with a composition made of triturated wood or leaves. The cylinders it forms are usually about five inches deep, and within this it constructs about the same number of cells proportionate to the small size of the insect. These are midsummer insects, coming forth in June and July; they are very local, but seem to abound in the vicinity of Bristol, whence Mr. Thwaites formerly sent me specimens. A very few days serve for the hatching of the larva, which spins a slight silken cocoon, and in this dormitory it reposes until its season again comes round. Under the influence of the following first genial spring weather, the larva is transmuted into the pupa, and the active little imago comes forth upon the settlement of our variable spring, in the merry days of June, and thus is perpetuated the circle of its existence, but which is sometimes abridged by its special parasite, the pretty little _Stelis octomaculata_. Many of the species in the males are distinguished by a peculiar armature of the apex of the abdomen; the second being named by Kirby from the circumstance. A very remarkable singularity distinguishes the males of the third species, in the fringe of short hair that runs along the flagellum of its antennæ. This, I believe, was first noticed by the late Mr. Bainbridge, a very active practical entomologist, who took the insect at Darenth or Birchwood, and distributed specimens with this manuscript name attached, which has since been appropriated by another entomologist to whom the science was wholly unknown at that time, but as it is scarcely consistent with scientific courtesy to adopt such a course, and as the MS. names of Linnæus and Kirby have been retained, where it was authorized by their being attached to undescribed species, I have restored to Mr. Bainbridge his just rights, and have claimed the same for myself, in the case of _Andrena longipes_, and which many cabinets must still possess with my name attached, in my own writing, unless their possessors have chosen to adopt the illegitimate parentage; for the entomologists of my own standing well know that I always freely distributed specimens to all who desired them of the many very desirable insects which I have captured in the course of my entomological career. The fourth and the ninth species, the _O. bicolor_ and _O. aurulenta_, have very much the same habits, both usually burrowing in sandbanks, sometimes however in wood, in which case the perforation, contrary to the mode of wood-drilling bees, is made upwards, a sagacity or instinct which saves it much trouble, for the particles as they are removed by the mandibles are passed beneath the insect, and their own gravity carries them downwards, and thus the insect saves itself the labour of conveying them out as they accumulate in inconvenient quantities. The cells in this case are placed end to end. When they burrow in the earth, the latter species often associate gregariously in large numbers, and if they select a cavity, instead of tunnelling it themselves, and it be too large to take one cell upon the others, they form them side by side, and thus fill the space. This is the case when they adopt snail-shells as the receptacle for their incunabula, and this is done by both these species, and the shells they select are the empty ones of _Helix nemoralis_, _hortensis_, and _adspersa_. The capacity of the latter shell being much greater than that of the others, and too wide for a single succession, she fills the interval by placing them side by side, and with the increase of the whorl of the shell towards its orifice she places them across the space, and thus completes her task. In the former shells, the cavity at first admits of the succession of but one upon the other, but with its enlargement she places them side by side, and this repeated fills the hollow. Its aperture is then closed with earth and pebbles or sticks agglutinated together, as described at the commencement. The _O. fulviventris_ burrows in wood, and upon this species the _Stelis phæoptera_ is parasitical; and that very pretty but extremely common species the _O. ænea_, in which the male is of a rich bronzy tint, and the female of a beautiful blue, verging sometimes to nearly black, burrows also in wood, although sometimes it capriciously selects old walls or chalk-cliffs, and is subject to the incursions of the same parasite. Perhaps the most extraordinary species is the _O. parietina_, figured and named by Curtis, and which he first found at Ambleside; it has since been found in the Grampians very considerably above the level of the sea, and it is thus essentially a northern species both from altitude and locality. It would appear that this species selects some flat stone of about a foot in surface, lying upon the ground over a hollow spot. Such a specimen, sent to the British Museum, had attached to its under side two hundred and thirty cocoons, indicative of a considerable colony, or perhaps the accumulation of successive years, as one-third of these cocoons were empty of tenants. These, in their new depository, continued developing themselves in the perfect state between March and June, males appearing first. When the transformations of the season ceased, five-and-thirty were still left to present themselves another year, and the following spring these were developed; thus, including those which had already escaped when the stone and its treasure was secured, three successive seasons were occupied in their transmutations. It may be a species that requires three years for its metamorphosis, and the whole deposit of cocoons may have been the result of three years’ accumulative structure, the vital activity of their northern life being perhaps more sluggish than in species frequenting the south. The last species the _O. rufa_, that in which the female is remarkable for its inverted horns, which must be for some use in its economy, is perhaps the most common of all. I have found it in abundance upon old walls with a sunny aspect at Erith, and throughout the pleasant Crays of Kent. It is indifferent as to the choice of its domicile, selecting either walls, where I have chiefly found them, sandbanks, or the decaying stumps of pollard-willows. Its processes are similar to those of some of the earlier described, but its larva is longer in full feeding, which, when it has consumed all its provender spins a tough cocoon of brown silk, wherein it undergoes its changes; some, depending much upon locality, pass into pupæ in the autumn, others hibernate as larvæ which are subject to destruction from the attacks of the _Chalcideous_ insect, _Monodontomerus dentipes_, previously noticed under _Anthophora_. Some of the _Chrysididæ_ also infest several of the species of this genus, and I have no doubt that _Stelis aterrima_ is parasitical upon one of them, although it has not been recorded. The various species frequent many flowers, especially those abundant in the locality they inhabit, but the _O. pilicornis_ chiefly affects the common Bugle (_Ajuga reptans_), and they much frequent composite flowers, especially the species of the genus _Hieracium_.

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