British Bees / An Introduction into the Studies of the Natural History and Economy of the Bees Indigenous to the British Isles

by William Edward Shuckard

Leachella, Curtis.

4. odontura, Smith, ♂. 4½ lines.

GENERAL OBSERVATIONS.

Named from the great development of the labrum, μέγα large, χεῖλος lip, which is characteristic of all the Dasygasters, and also of some of the proximate Nudipedes, those parasitical upon them, Stelis and Cœlioxys, and which, too, resemble the sitos in the expansion and dentated formation of their mandibles, although they do not use them for the same purposes; this again exhibits an analogy of structure, that appears in the parasite to be merely corroborative of identity of existence.

These are more essentially summer insects than the majority of the preceding genera, although some of them present themselves with genial spring weather. The genus may be separated into two distinct divisions by the peculiar dilatation of the tarsi of the males of some of the species, but such division is not indicative of a difference of habits, as is distinctly the case in the genus Anthophora, and in which these combined circumstances Mr. Kirby suggested as acceptable for generic division, or, as he called it, the institution of another family. But in these we find in both divisions both wood-borers and earth-tunnelers, and some species are indifferently either as suits their accidental convenience. The general appearance of the insects is more that of ordinary bees, and the sexes are more approximate in their habit than is usually the case.

With this genus commences essentially those designated as artisan bees, although Colletes might very suitably come under that denomination. The species themselves of the genus are called leaf-cutters, from the habit they have of cutting pieces from the leaves of various shrubs and trees, for the purpose of lining their nests. The description of the operations of one species will apply precisely to that carried on by all, the occasional difference between them being the selection of the leaves of distinct plants; and it will exhibit the patient industry and perseverance with which these little upholsterers carry on their labours.

Thus M. centuncularis, the type of the genus, burrows in decaying wood or in brick walls, and sometimes also in the ground, and makes use of the cuttings of rose leaves,—not the petals,—and the leaves of the annual and perennial Mercury (Mercurialis annua and M. perennis). The M. ligniseca bores into sound Oak and the Mountain Ash, as well as into putrescent Elm, and uses Elm leaves to line its nests, sometimes called centunculi from their being as it were patched together. This is the largest of all our species, and is found very abundantly everywhere around London frequenting the flowers of the Thistle. The M. argentata, Fab., or Leachella of Kirby, is perhaps the prettiest of all the species, and forms its tunnels in sandbanks. I do not know what leaves this species selects, which used to be extremely rare, indeed for a long time only known by the specimen in the British Museum, until that ardent entomologist the Rev. F. W. Hope, to whom the University of Oxford owes its superb entomological collection, brought it in abundance from Southend, where, during his brief annual stay at his residence there, he used to find it in the grove which runs under the cliff edging the terrace of the village; it is extremely local, as that and Weybridge, in Surrey, are the only two spots where I have known it to be found. It is one of the most vivid fliers among the bees, and darts about, especially during brilliant sunshine in June, with the velocity of a sand-martin, and its note is shrill, but harmonious; it is not often caught upon flowers, being so extremely alert, but has been seen to visit the common Viper’s Bugloss (Echium vulgare). The M. odontura, the last of the second division, which is known only in a single male specimen in the cabinets of the British Museum, is one of Dr. Leach’s west country captures, of which nothing precise is known, and it is only noticed here on account of the singular peculiarity of the armature of the apex of its abdomen, which brings it closer to the genus Osmia in that particular, although the majority of the males of the genus have the terminal segment slightly furcated.

In these observations I have commenced with the division which contains the type, and to which the present name of the genus would attach from that circumstance, were it ever thought desirable to separate those species, which have dilated anterior tarsi in the males, into a distinct genus, but which I could scarcely recommend. In the arrangement of the species in the preceding list, I have placed these latter first, from their more symmetrical appearance in the cabinet, by leading down to the terminal smaller species in due order, from these larger and more conspicuous ones.

The M. Willughbiella and maritima prefer decaying wood, and they have been found upon decaying Willows in the Midland Counties in extreme abundance; they might be called gregarious were the material within which they burrow connected in a continuous plane. The M. Willughbiella makes use of the leaves of the Rose and of the Laburnum, but the M. maritima seems to prefer the leaves of the Sallow. The M. circumcincta invariably burrows in banks, confirming the semi-gregarious habits of the genus, where it forms large colonies, and it is only by accident that it constructs secluded and solitary nests; it also makes use of rose leaves for lining its apartments. The insects are subject to the molestation of bee-parasites of the genus Cœlioxys, the C. quadridentata having been bred from the cells of this latter species,—that parasite also frequenting the M. Willughbiella, and the C. vectis is well known to infest the M. maritima. Thus, it appears to be only the species of this division with the dilated tarsi that are exposed to such incursions, there being no record of parasites frequenting the division in which the males have simple anterior tarsi. Besides this bee-parasite, they are also subject to the attacks of some dipterous insect, whose larvæ destroy the larvæ of the Megachile. Much difficulty exists in separating the females of some of the species from each other; in others the specific character is sufficiently noticeable. It is a singular concomitant that those males with the dilated anterior tarsi have the apical joint of the flagellum of the antennæ considerably compressed and also dilated laterally.

The proceedings of these bees are very curious. Although the tubes they usually form are long, they are so constructed as not to branch far away from the exterior of the material into which they bore,—sound or putrescent wood or earth, or old mortar joining the bricks of walls,—if in the second material, they usually follow the putrescent vein, and their tunnel in every case is rarely further than an inch or an inch and a half from the external surface. Both the sides of the tube, and the cells they form within them, will necessarily vary in diameter and length with the size of the species, but in the larger species they are about an inch and a quarter long and half an inch in diameter. Some entomologists have surmised that different species use the leaves of different plants for lining their cells; this, however, is not strictly the case, as shown in the preceding remarks; but, although not so, the series of nests in the same tube are always lined with cuttings from the same plant; perhaps a varying caprice operates upon each day’s labours and changes the plant, influenced by the drift of the wind or some casual freak.