The two divisions which our native species of this genus form, might very consistently constitute two genera, differing so much as they do both in habit and habits. In the first section the males totally differ from their females, the latter being black and the pubescence of their partners fulvous, and whose intermediate legs are so much longer, and are decorated besides with tufts of hair upon their plantæ, neither peculiarity being found in those of the second section, which conform more regularly to the ordinary type of structure. The first section also nidificate gregariously, forming enormous colonies which consist of many hundreds; whereas the second are solitary nidificators, and at most half-a-dozen may be found within as many square yards of territory, and one species, the A. furcata, diverges considerably from the ordinary habits of the genus, and closely approaches those of the foreign genus Xylocopa, but its structure necessarily retains it within the boundaries of the genus. All these insects exhibit the peculiar characteristic of the Scopulipedes, in the insertion of the second joint of the posterior tarsi at the very bottom of their plantæ, conjunctively with the polliniferous scopa, placed externally upon their tibiæ and plantæ, in which characteristics the Andrenoid Macropis remarkably resembles them, and which I have noticed in my remarks upon that genus.
The first section burrows in banks, where their colonies are extremely numerous. In the tunnels which they form they construct several elliptical cells which they line with a delicate membrane of a white colour, formed by a secretion or saliva derived from the digestion of either the pollen or the honey which they consume. Each cell when formed is stored as usual, and the egg deposited, and then it is closed. There is but little variation in these processes among all the solitary bees, excepting in the case of the artisan bees and the more elaborate processes of Colletes, in which, however, the casing is merely thicker, arising from several layers of the coating membrane. The perfect insects make their appearance during the spring and summer months, their successive maturity being the result of the previous summer and autumn deposit of eggs. They pass the winter and spring in the larva state, and undergo their transformations into pupa and imago with but slight interval, and only shortly before the appearance of the perfect insect. When first presenting themselves they are certainly very handsome insects, and if carefully killed preserve their beauty for many years in the cabinet. I have found the retusa, Linn., (Kirby’s Haworthana,) in enormous profusion at Hampstead Heath, indeed, so numerous were they, that late in the afternoon, upon approaching the colony, they, in returning home, would strike as forcibly against me as is often done by Melolontha vulgaris or Geotrupes stercorarius. In equal abundance I have found the A. acervorum at Charlton, where I have experienced a similar battery. This is the insect which Gilbert White, in his letters from Selborne, describes as having found in numbers at Mount Caburn, near Lewes, a spot I have often visited in my schoolboy days. This section is subject to the parasitism of the genus Melecta, whose incursions are very repugnant to them, and which they exhibit in very fierce pugnacity, for if they catch the intruder in her invasion they will draw her forth and deliver battle with great fury. I have seen both the combatants rolling in the dust, the combat and escape made perhaps easier to the Melecta by the load the Anthophora was bearing home. Upon the larva also of this bee it is said that the larva of the Heteromerous genus Meloë is nurtured; this I have never been able to verify, but I believe the fact is fully confirmed. This beetle is closely allied to the Cantharides, or blister-beetles, and it itself exudes a very acrimonious yellow liquid when touched or irritated. Two of the Chalcididæ also infest their larvæ, which they destroy; one is the Melittobia, named thus from its preying upon bees; it, like the majority of its tribe, is exceedingly minute, and of a shining dark green metallic colour. It is peculiar from having its lateral eyes simple, and in possessing besides three ocelli. The other genus is Monodontomeris, an equally small insect, which, although living upon the larva of Anthophora, is equally preyed upon by that of the Melittobia. The universal scourge, Forficula, is a great devastator of these colonies, where, of course, it revels in its destructive propensities.
The insects of the second division I have never been able to track to their burrows, but have always caught them either on the wing or on flowers, especially upon those of the common Mallow, and I have found both species all round London. They are said also to frequent the Dead Nettle (Lamium purpureum). The A. quadrimaculata burrows in banks, and its processes are scarcely different from those of the preceding species, only its habits are solitary. In flight it is exceedingly rapid, and thus much resembles Saropoda. But the A. furcata bores into putrescent wood, in which it forms a longitudinal pipe subdivided into nine or ten oval divisions, separated from each other by agglutinated scrapings of the same material, very much masticated, the closing of each forming a sharp sort of cornice; each of these cells is about half an inch in length, and three-tenths of an inch in diameter, the separations between them being about a line thick. These pipes or cylinders run parallel to the sides of the wood thus bored, an angle being made both at its commencement and its termination, and thus the latter permits the ready escape of the developed imago nearest that extremity, which being the first deposited, that cell being the first constructed, it necessarily becomes the first transmuted, and thus has not to wait for the egress of all above it.
All these insects are usually accompanied by their partners in their flight, and their amorous intercourse takes place upon the wing.
Genus 12. Saropoda, Latreille.
([Plate VII.] fig. 2 ♂♀.)
Apis ** d, 2, a, Kirby.
Gen. Char.: Head transverse, as wide as the thorax, very pubescent; ocelli placed in a triangle, the anterior one low towards the face; vertex slightly concave; antennæ short, filiform, basal joint of flagellum globose, the second joint subclavate and the longest, the rest short and equal; face flattish, short; clypeus forming an obtuse triangle, slightly convex; labrum quadrate, with the angles rounded; mandibles obtusely bidentate; cibarial apparatus long; tongue very long and slender, but gradually expanding towards half its length and then as gradually tapering to the extremity and terminating in a small knob, its sides throughout being fimbriated with short delicate down; paraglossæ one-third its length, membranous, very delicate, and tapering to a point; labial palpi slender, membranous, the joints conterminous, the basal joint more than half the length of the tongue, the remainder short, the second the longest of these three, and all tapering to the pointed apical one; labium scarcely one-third as long as the tongue, rather broad, bifid at its inosculation; maxillæ nearly as long as the tongue, gradually diminishing from its basal sinus to a point at its extremity; maxillary palpi four-jointed, about one-third the length of the maxillæ, the basal joint short, robust, the second tapering from its base to the third joint, which is rather shorter and subclavate, the terminal joint slender. Thorax very pubescent, rendering its divisions inconspicuous; scutellum and post-scutellum lunulate and convex; metathorax truncated; wings as in Anthophora, with three marginal cells closed, the second forming a truncated triangle, and receiving the first recurrent nervure near its centre, the third bulging outwardly and receiving the second recurrent nervure at its extremity; legs very setose, especially the posterior tibiæ externally, and their plantæ both externally and internally, but the setæ are longer on the exterior of the joint, the second joint of these tarsi inserted beneath, and before the termination of their plantæ, the terminal joint longer than the two preceding; claws bifid, the inner tooth distant from the apex. Abdomen subovate, very convex, truncated at its base, where it is densely pubescent, the fifth segment fimbriated with stiff setæ, and the terminal segment having a central triangular plate with rigid setæ at its sides.
The MALE scarcely differs, excepting in the characteristic sexual disparities of slightly longer antennæ, and considerably longer intermediate tarsi, whose apical joint is very clavate.