This genus was named by Fabricius from the Nomades, a pastoral Scythian tribe, in allusion to the assumed wandering habits of the insects, and it is the fact indeed that they are usually found leisurely hovering about hedge-rows, or the banks enclosing fields, or about the metropolis or nidus of any bee upon which they are parasitical. They are the gayest of all our bees, their colours being red or yellow intermixed with black, in bands or spots; they are also very elegant in form, which is after the type of that of the most normal Andrenidæ, and to which they have a further affinity by the silence of their flight, and by their parasitism upon many of the species of that subfamily. From their very general resemblance to wasps in colour they are often mistaken for wasps, and are popularly called wasp-bees, although they have none of the virulence of that vindictive tribe, for although all the females are armed with stings, they are not prompt in their use, or if roused to defence the puncture is but slight. In addition to their prettiness of colour and elegance of form, they have a further attraction in the agreeable odours they emit, sometimes of a balmy or balsamical, and sometimes of a mixed character, and often as sweet as the pot-pourri, and occasionally pleasantly pungent. A fine string of specimens of the several species is a great ornament to a collection, but to secure this in its perfection some care is required in the mode of killing them. Their colours are best permanently retained by suffocating them with sulphur, which fixes the reds and yellows in all their natural and living purity. My method was in my collecting excursions to convey with me a large store of pill-boxes of various sizes, and as I captured insects in my green gauze bag-net, I transferred them separately to these boxes. When home again I lifted the lids slightly on one side and placed as many as would readily go beneath a tumbler, and then fumigated them with the sulphur. This is a better plan than killing them with crushed laurel-leaves, for it leaves the limbs much longer flexible for the purposes of setting, whereas the laurel has a tendency to make them rigid, and this rigidity is extremely difficult to relax, whereas the setting of those killed with sulphur, if they are kept in a cool place, may be deferred for a few days, until leisure intervene to permit it, and even then if they become stiffened they are readily relaxed for the purpose.
A division might very consistently be established in the genus by the separation of those which have subclavate antennæ, and the segments of whose abdomen are slightly constricted; these also are more essentially midsummer insects, and usually frequent the Ragwort. This is the only genus of parasites amongst the true bees whose parasitism is directed exclusively upwards in the scientific arrangement; the parasitism of all the rest of the genera of Nudipedes bears upon the genera below them in the series. Some of the species of the Nomadæ attack more than one species or one genus, but the majority are strictly limited to but one genus and one species. The genera obnoxious to this annoyance are Andrena, Halictus, Panurgus, and Eucera; the latter two have but one of these enemies each, the Nomada Fabriciana infesting the Panurgus Banksianus, and the N. sexfasciata frequenting the Eucera longicornis. Under Panurgus I have alluded to the relative abundance of the parasite at the metropolis of its sitos. As far as known, the other species are thus distributed. Those frequenting several indifferently are the Nomada alternata, Lathburiana, succincta, and ruficornis, which are found to infest Andrena Trimmerana, tibialis, Afzeliella, and fulva, without displaying any choice; whereas others confine themselves to one sitos exclusively: thus Nomada ochrostoma limits itself to Andrena labialis; N. Germanica to A. fulvescens; N. lateralis to A. longipes; N. baccata to A. argentata; N. borealis to A. Clarkella; N. Fabriciana to Panurgus Banksianus; and N. sexfasciata to Eucera longicornis. Observation has not yet fully determined whither each species of Nomada conveys its parasitism; several infest the Halicti, especially the smaller species; the association of these it is difficult to determine; I have usually found several of the small Halicti burrowing together in the vertical surface of an enclosure bank, and several of the small Nomada hovering cautiously opposite, now alighting and entering a burrow, then retreating backwards and winging off. I lost patience in endeavouring to combine the species by the aid of blades of grass or slight straws thrust into the aperture, but the crumbling nature of the soil frustrated my wishes, and I abandoned the attempt. This field of observation is widely open to the exertions of observing naturalists, and the novelty of their discoveries would well reward the toil of the undertaking, for it would not be long before they gathered fruit.
Genus 15. Melecta, Latreille.
([Plate XI.] fig. 1 ♂ ♀.)
Apis ** a, Kirby.
Gen. Char.: Head transverse, scarcely so wide as the thorax; ocelli in a triangle on the vertex; antennæ filiform, rather robust, and but slightly geniculated, the scape not longer than the two following joints, the second joint of the flagellum the longest and clavate, the rest short, nearly equal, and the terminal one laterally compressed at its extremity; face flat, very pubescent; clypeus short transverse, lunulate, convex; labrum irregularly gibbous, obovate; mandibles strongly bidentate; tongue long, slightly expanding towards the middle and thence tapering to the extremity, and with a central line; paraglossæ scarcely half the length of the tongue, almost setiform, but robust at the base; labial palpi more than half the length of the tongue, the two first joints membranous and very slender, the first longer than the rest united, the second about half the length of the first, and terminating acutely, the third not more than one-fourth the length of the second, and inserted laterally before its termination, the fourth about as long as the third, and, like it, subclavate, both being more robust than the second; labium not half the length of the tongue, and acutely triangular at its inosculation; maxillæ subhastate, not quite so long as the tongue; maxillary palpi five-jointed, about one-third the length of the maxillæ, the basal joint clavate, short, and robust; the second elongate, subclavate, the remainder gradually but slightly diminishing in substance and length, the terminal not so long as the basal joint. Thorax very retuse, and its divisions scarcely distinguishable; scutellum bidentate; metathorax abruptly truncated; wings with three closed submarginal cells, the second the smallest, irregularly triangular, and receiving the first recurrent nervure just beyond its centre, the third submarginal considerably larger than the second, sublunulate, but angulated externally and receiving the second recurrent nervure about its centre; the legs robust and spinulose, especially the tibiæ externally (where they are very convex) and the femora beneath; the claws short, strong and bifid. The Abdomen conical, truncated, and retuse at its base, the apical segment with a central triangular plate ridged laterally, and fimbriated at its sides with strong setæ.
The MALE scarcely differs in personal appearance, excepting that its antennæ are more robust and its ornamental pubescence is more profuse, its posterior tibiæ very robust and almost triangular, and the terminal segment of its abdomen slightly emarginate and concave at its extremity.
NATIVE SPECIES.
1. punctata, Fabricius, ♂ ♀. 6 lines. ([Plate XI.] fig. 1 ♂ ♀.)