Wild Bees, Wasps and Ants Part 2

They are dull-brown coloured creatures rather like a stout hive bee in form (pl. C, 20). They all collect pollen on the underside of their body. They burrow either in decayed wood or in the ground, but they make their cells of pieces of leaves which they cut off from rose bushes or other plants; these cells when completed are wonderful works of art. Probably some of my readers may have noticed rose leaves with semicircular pieces cut out of them, and often with almost circular ones; this is the work of the leaf cutter (fig. 7).

[Ill.u.s.tration: PLATE C.

20. _Megachile maritima_, _female_. 21. _Coelioxys conoidea_, _male_. 22.

_Coelioxys conoidea_, _female_. 23. _Nest of Megachile willughbiella._

[_face p. 52._ ]

{53} She alights on a leaf, holds on to the edge of the piece she wants to cut off with her legs, and then cuts it out by means of her jaws, or mandibles; as soon as it is cut free she uses her wings and so prevents herself from falling, and goes off with the cut off piece safely held under her body by her legs. I have frequently seen bees flying home with their leafy burden, and once or twice I have seen them cutting the pieces out.

They cut round the piece they select with great rapidity--the marvel is that they can arrange so exactly as not to fall when the last attachment is removed. The pieces they cut have to be of several shapes in order to build up the cell they require; some are more or less lozenge shaped, some almost circular; the cells they make are somewhat thimble-shaped. The lozenge-shaped pieces are used to build up the sides and lower end of the cell, and the circular pieces to close it in with at the top; it is all cemented together with a gluey substance excreted by the bee. The burrows of the leaf-cutters are made, as stated above, either in the ground or in rotten wood. I have never had a subterranean nest to examine, but have had several nests in rotten wood under my notice, one of which is now before me (pl. C, 23). It is in a piece of very {54} soft willow, almost in a touchwood condition. So that by carefully cutting away the wood I have been able to expose the whole series of cells. Two distinct burrows run almost parallel to each other; both of them are slightly curved and each has contained six cells; these are about half an inch long, and they fit one over another in the tube as closely as possible so as to look like two long thick green worms. Each cell is composed of many pieces of leaf, and the final plug which closes the cell is often made of several rounds of leaf one over the other. The amount of labour taken by the mother bee to make these cells must be enormous. The cells are provisioned like those of any other solitary bee with pollen, etc., and the egg is laid upon it. Most of the leaf-cutters have their attendant cuckoos, which are rather smaller than themselves, of a deep black with white bands on the sides of the body.

The female has a very pointed tail, and the male's body ends in a series of spine-like projections (pl. C, 21, 22).

{55}

OSMIA AND ITS HABITS

I have tried as much as possible to avoid scientific names, but the misfortune is that there are hardly any popular names in use which can be attached for certain to any particular species, and unless this can be done it is of no use using vague names like the "Carpenter Bee", the "Mason Bee", etc. There are many carpenter bees and many mason bees, and though their habits may be alike in this one particular they differ among themselves in the way they use their tools, and it is necessary to know which one we are talking about. It is a common thing to hear people inveighing against Latin names, etc., but they forget that there are no English ones in use, and what is more important, that Greek and Latin names are common property to all nations, so that we can all know what we are talking about, whereas if we call an insect by an English name and the Russians {56} call it by a Russian name, the difficulty of coming to a mutual understanding is very great. This is only an aside to justify the use of cla.s.sical names. I quite feel that for popular use in this country a good series of English names might be useful, but we have not got one, and it would require a great deal of care and thought to frame a nomenclature which would really be useable by the persons who require it.

I have made these remarks here because _Osmia_ is a genus whose members vary very much in their habits, and some species of which, like sensible beings, adapt their habits to their surroundings, so that no name such as carpenter bee, etc., would apply to all the species, or, as a rule, even to one. _Osmia rufa_ especially adopts several methods of nesting. This little bee is clothed more or less all over with yellowish hairs; it is compact in shape like all the other species of _Osmia_, and like them collects its pollen on the underside of the body. It may sometimes be seen flying up and down the walls of a house looking for a crevice to build in, but it is not the least particular as to where to form its cells. In one memorable case the female selected a flute {57} which had been left in a garden-arbour.

The bee constructed fourteen cells in the tube of the instrument, commencing its first cell a quarter of an inch below the mouthhole. The flute is preserved in the Natural History Museum at South Kensington. At other times this species burrows in the ground, at others it makes its cells in crevices of old walls; it has been known to build in a lock, and is said sometimes to inhabit snail sh.e.l.ls. Other species of _Osmia_ almost always burrow in banks, but in no case does a habit seem to be uniformly adopted by a species. One well known and rare species, _Osmia leucomelana_, is a regular bramble-stick species, tunnelling down the pith in the centre of the stalks, but I once found it to my surprise in fair numbers nesting in a sandy bank. Other species again, as a rule, select snail sh.e.l.ls to build in; they find an old disused sh.e.l.l lying about in some sheltered place and adapt it to their purposes, commencing their cells singly in the narrow whorls of the sh.e.l.l and side by side as they approach its mouth, i.e. if the sh.e.l.l be a wide-mouthed one like the common garden snail (_Helix aspersa_). F. Smith, who gives a very interesting account of these {58} creatures in his _Catalogue of British Hymenoptera in the British Museum_, mentions a case where the bee finding the larger whorls of the sh.e.l.l too wide constructed two cells across the whorl. Another very interesting case given by Smith is of a nest of many cells of the rare _Osmia inermis_ (which in his days was known as _Osmia parietina_). A slab of stone, 10 inches by 6, was brought to him with 230 coc.o.o.ns of this _Osmia_ attached to its under side; when found in the month of November, 1849, about a third of them were empty; in March of the following year a few males made their appearance and shortly afterwards a few females, and they continued to come out at intervals till the end of June, at which time he had 35 coc.o.o.ns still unopened; in 1851 some more emerged, and he opened one or two of the closed ones and found that they still contained living larvae; he closed them up again, and in April, 1852, examined them and found the larvae still alive; at the end of May they changed to pupae and appeared as perfect insects, the result being that some of the specimens were at least three years before reaching maturity. {59}

There is a nest of yet another style adopted by one of our species (_Osmia xanthomelana_). This is formed of a series of pitcher-shaped cells made of mud, constructed at the roots of gra.s.s. The species which makes it is rare and seems to have its headquarters on the coasts of Wales, although it has occurred in the Isle of Wight and elsewhere. This species also is not constant in its habits, as it has been known to make its cells underground.

A very curious habit was noticed some years ago by Mr. Vincent R. Perkins in another species of this genus (_Osmia bicolor_; pl. D, 28); the species nests in the ground or in snail sh.e.l.ls, but, in the case under his observation, Mr. Perkins found that the little bees covered up all the snail sh.e.l.ls in which they had built their cells with short pieces of "bents" so as to make a little hillock over each about two or three inches in height, somewhat resembling a miniature nest of _Formica rufa_, the large horse ant, each mound containing hundreds of pieces. This is the only record I know of this habit, which must entail a large amount of labour for the bee.

These varying habits in the same species {60} show pretty clearly that these little creatures are not driven by any blind instinct in the adoption of their methods of nest building: they appear to have a distinct power of choice and adaptation according to their environment, unless of course it can be shown that the offspring of, say, a snail sh.e.l.l inhabitant follows its parents' habits, and that that of a ground borer does the same--but even that would not explain the case given by F. Smith, and quoted above, where an _Osmia_ had filled up the whorls of a sh.e.l.l and then, finding the final whorl too large, placed two cells horizontally to fill it: that seems to indicate distinct design on the part of the bee and would be hard to explain as due to instinct. Unfortunately, with the exception of a very few, the species of _Osmia_ are rare in this country, so that few opportunities are available for studying their habits, which are certainly amongst the most interesting of any genus.

[Ill.u.s.tration: PLATE D.

24. _Anthophora pilipes, male._ 25. _Anthophora pilipes, female._ 26.

_Melecta armata, female._ 27. _Anthidium manicatum, female._ 28. _Osmia bicolor, female._ 29. _Bombus terrestris, female._ 30. _Bombus lapidarius.

female._ 31. _Psithyrus rupestris, female._

[_face p. 61._ ]

{61}

A COLONY OF ANTHOPHORA

_Anthophora pilipes_ (pl. D, 24, 25), one of our early spring bees, often forms enormous colonies. I have sometimes seen sandpits in which the sides were riddled all over with holes of this species, and where the insects were in such numbers that a distinct hum was audible from the vibration of their wings. In such colonies one is sure to detect some of their cuckoo a.s.sociates, _Melecta armata_ (pl. D, 26). They are deep black bees, much of the same size as their hosts but with more pointed tails and with a small spot of snow-white hairs on the side of each segment of the body; like other cuckoos they sail about in a more demure way than their hosts, but a more lively scene than a large colony of _Anthophora_ can hardly be found.

The _Anthophora_ provisions its cells with honey and pollen, and its egg in consequence floats on the top--the {62} number of cells varies from five or six up to ten or eleven.

_Anthophora pilipes_ has a very close relative in _Anthophora retusa_, which also forms large colonies, but it is as a rule less common. These two species are exceedingly alike, in fact it requires some skill on the part of the observer to differentiate their females. They are both black and clothed with black hairs, and both have yellow pollen-brushes, but in _retusa_ the hairs are shorter and not quite of such a deep black as those of _pilipes_, and the spurs of the tibiae are pale, whereas in _pilipes_ they are black. The males, however, differ widely, although much alike in colour; in _pilipes_ the feet of the middle pair of legs are clothed with enormously long hairs, the basal joint has a dense fringe of black hairs in front and some long black hairs behind (see pl. D, fig. 24); in _retusa_ the basal joint of the middle pair of feet have a fan-shaped fringe of black hairs, and the rest of the joints are clothed with longer hairs, but not long enough to be specially noticeable. _A. retusa_ is visited by the same cuckoo as _A. pilipes_ and also by its rare ally _Melecta luctuosa_, which only differs from _armata_ {63} (pl. D, 26) in the larger and squarer spots of the body and various small structural characters hardly appreciable except by specialists. The Anthophoras have other parasites besides their cuckoos; one is a beetle, which, however, is rare, and which lays its egg in the _Anthophora_ cells; the other is a very minute member of the Hymenopterous family, whose larva when hatched feeds upon the larva of the bee. Notwithstanding these disadvantages both species are abundant, although _retusa_ is more local than _pilipes_. A very interesting fact connected with this genus has just been communicated to me by the Rev.

F. D. Morice. John Ray, who lived in the seventeenth century, mentions in his book _Historia Insectorum_ (published posthumously in 1710), p. 243, that a large colony of a bee, which from his description was clearly an _Anthophora_, as he specially calls attention to the great difference between the males and females, inhabited a certain locality at Kilby near "Hill Morton" in Northamptons.h.i.+re. Mr. Morice, who for many years resided at Rugby, knew Hillmorton, as it is now spelled, well, and tells me that a large colony of _Anthophora_ was in that same locality when he knew it only {64} a few years ago. Of course there is no proof that it has been there throughout the intervening period, but there seems to be no reason to doubt it, and if so it is a most interesting case of a persistent colony.

{65}

BEES AND POLLEN-COLLECTING

Bees whether solitary or social enter flowers for the sake of the honey in their nectaries and the pollen on their anthers. In some cases the flowers automatically deposit pollen on the bees during the operation, which enables them to fertilize other flowers of the same species, but the pollen which the bee requires for its own use has to be worked for and collected on organs specially adapted for the purpose. These vary very much in the different families and genera; they exist only in the females, and, if the males get covered with pollen, as they often do, it is probably more by chance than purpose, and it is doubtful if it is of any value to the brood, although no doubt useful in fertilizing other flowers. All our bees, as has been pointed out before, are clothed more or less with branched or feather-like hairs, which would appear to be admirably adapted for the collecting of pollen. {66} At the same time some species which have their bodies clothed with branched hairs have simple or spirally grooved hairs on the collecting organ--others collect on very much branched hairs--so that there seems to be no exact relations.h.i.+p between the plumosity of the hairs and their utility in collecting. The collecting brushes are either on the hind legs or, as in some cases, on the ventral surface of the body. In a female _Andrena_, the hind leg has a tuft of curled hairs near the base of the leg, and a more or less heavy brush on the outside of the tibia or s.h.i.+n (fig. 8). When a female returns after a collecting expedition these specially hairy regions are a ma.s.s of pollen grains, and the "beautiful yellow legs", so often remarked upon in some bees, are not always due to the colour of the hairs but to that of the grains of pollen adhering to them. The genera which collect on the under surface of the body have to visit flowers where the anthers lie in such a position that they can transfer the pollen on to it; the pea flower tribe are favourites with them, and also the _Compositae_. All this section have long tongues so that they are able to reach the nectaries of {67} [Ill.u.s.tration: FIG. 8.]

[Ill.u.s.tration: FIG. 9.] plants with long tubular flowers. In visiting these the pollen is often deposited on the back of the bee; this it is able to transfer to its under side by means of the brushes on its feet or tarsi.

The arrangements of the humble bees for pollen gathering are altogether different from those mentioned above. They have the hind s.h.i.+n outwardly s.h.i.+ning and rather concave, with a series of long curved hairs running down each side of it and partly curving over it, so that they carry their ma.s.s of pollen in a sort of basket, scientifically called the "corbicula" (fig.

9); this would be impossible if the pollen were gathered dry, as it is by most of the solitary bees, so the bee moistens it on the flower with the nectar she has been sucking so as to make it sticky, and then transfers it into her basket by means of her foot brushes. The pollen therefore on the hind leg of a humble bee is all in one ma.s.s and can be {68} removed as such. When the bee reaches her nest this must of course save her the trouble which the solitary bee must have of cleaning off all the separate grains of pollen which are mixed up among the hairs.

A word or two may be convenient here on the combs and cleaning apparatus of bees. Any one who has watched a bee clean itself will have noticed that the front legs work more or less horizontally--a bee will lower its head and bring its front leg over it with a curved motion--and that it will clean the sides of the face with a sort of shaving-like action, also that the antennae are apparently pulled through the foot-joint in a remarkable way, often many times in succession. Now the foot of a bee consists of five joints, and is clothed with bristly looking hairs. If these hairs be examined through a microscope they will be found to be more or less razor-shaped, having a thick back and a dilated wing or knife-like blade (fig. 10). In some the blade is of some width, and the edge is evidently very sharp: these hairs or spines no doubt do the cleaning work, and admirably adapted they are to the purpose. The antennae-cleaner {69} [Ill.u.s.tration: FIG. 10.] [Ill.u.s.tration: FIG. 11.] [Ill.u.s.tration: FIG. 12.]

(it may possibly be used for other purposes too) is a still more wonderful adaptation; in the basal joint of the foot there is a semicircular incision, which, when examined under the microscope, is seen to be a small toothed comb. The foot itself fits into the tibia or s.h.i.+n, and at the apex of the latter is a modified spine which is dilated on one side into a wing, or knife-like blade; this shuts down on to the semicircular comb, and the insect by pa.s.sing the antennae between the two can clean off anything which may have stuck to it (fig. 11). When we come to examine the other legs we find that the inner surface of their tibiae and tarsi, i.e. that which is nearest the body, is clothed with hairs which have the points dilated and spade-like (fig. 12), which {70} allowing for the different action of the hind legs makes them just as good cleaners as the razors of the front pair; the spurs at the apex of the tibiae, which are known as the _calcaria_, are also doubtless useful for cleaning purposes, and this is specially suggested by the beautiful saw-like form which they a.s.sume in some species; although there is no actual semicircular comb in the first joint of the tarsi, yet there can be little doubt that the spur and this joint in conjunction can act as a cleaning organ very much in the same way as the more elaborate arrangement in the front legs. Any one who has the opportunity of examining the hairs of bees under a microscope will be amply repaid for the trouble in noticing the beautiful shapes and structures which these organs a.s.sume. (Figs. 13-18; 17 showing pollen grains adhering.) At one time, when I was specially examining bee hairs, I shaved the various parts of a large number of species and mounted their hairs dry in microscopic slides, merely securing the cover gla.s.s with liquid glue; this was twenty years ago, and many are still quite good. It may seem a difficult operation to shave a bee, but {71} the hairs come off very easily, and with a sharp dissecting knife for a razor as many hairs as one wants are almost immediately at one's disposal.

[Ill.u.s.tration: FIG. 13.]

[Ill.u.s.tration: FIG. 14.]

[Ill.u.s.tration: FIG. 15.]

[Ill.u.s.tration: FIG. 16.]

[Ill.u.s.tration: FIG. 17.]

[Ill.u.s.tration: FIG. 18.]

{72}

ON BEES' TONGUES, AND HOW THEY SUCK HONEY

In order to understand how a bee sucks honey it will be necessary to go into some rather careful details as to the construction of its tongue and mouth organs. These I will make as short and simple as I can, but the apparatus is a very complicated one, and it will be impossible to describe it without a good deal of technical phraseology.

The tongue has always been considered such an important feature in a bee's structure that it has been made the chief basis of their cla.s.sification. On this subject I will only say that there are three princ.i.p.al types of tongues--a short bifid tongue (fig. 19, 3[1]), resembling those of the fossors; a short pointed one, shaped somewhat like a spear head (fig. 19, 2, 2a); and a long parallel-sided, ribbon-like tongue (fig. 19, 1, 1a). The bees are cla.s.sified on what is considered to be an {73} ascending scale, beginning with the bifid-tongued species, through those with the short spear shaped tongues to the higher forms, which have this organ elongate and parallel-sided.

[Ill.u.s.tration: FIG. 19.]

The tongue is the central organ of an elaborate combination of mouth parts, which I will now try to explain. If we turn a bee's head over and look at its underside we shall find a deep cavity, filled up with the base of this combination which fits into it. If we extend the tongue (a humble bee is a good subject on account of its large size, fig. 20) so as to draw its base out of the cavity, we shall find that in the edge of each side of the cavity there is articulated a short rod (20, A), more or less dilated at its apex, called {74} the _stipes_; on the flattened ends of these rods there swings a joint shaped something like the "merrythought" bone of a chicken, called the _lora_ or reins (20, B), to the central angle of which are suspended the pieces of the apparatus which terminate in the tongue.

This V-shaped joint can swing over on its feet, and can therefore lie either between the _stipites_ or rods with its angle pointing towards the tail of the bee, or in the opposite direction with its angle projecting beyond them and pointing forwards. It will at once be seen that by this turn of the V the tongue can be projected a distance equivalent to twice the length of the V.

This V-shaped joint varies much in the length of its arms, which are much longer in the long-tongued than in the short-tongued bees.

When we examine the parts that are suspended from this joint, we shall find that the actual tongue is separated from it by two distinct pieces; the first (i.e. that next to the _lora_) a short joint (the _submentum_, 20, C), the second (the _mentum_, 20, D) a long semi-cylindrical joint which holds as in a trough the softer parts at the base of the tongue. From the apex of the _mentum_ {75} project three organs; the central one is the actual tongue (or _ligula_, 20, E), and on each side are the organs which are called the _l.a.b.i.al palpi_ (20, F); these in the long-tongued bees more or less fold over the base of the tongue and protect it. There are two other large and important mouth parts called the _maxillae_ (20, G); these articulate on to the flattened apices of the _cardines_, outside the articulation of the feet of the _lora_, and extend on each side of the _mentum_; they also have flattened blades sheathing, when closed, the whole of the _mentum_ above, as well as the base of the tongue.

[Ill.u.s.tration: FIG. 20.]

So far we have been looking at the back of the head and mouth parts; if we now look at the front we shall see the _maxillae_; if we open these we shall see the tongue lying between the {76} l.a.b.i.al palpi, and at the base of the tongue we shall see two little sheaths called the _paraglossae_; above these the softer parts lying in the trough of the _mentum_; from the base of the _mentum_, connecting with the _maxillae_, there extends a membrane which entirely invests the s.p.a.ces between the bases of these organs and extends up to the mouth. A membrane also extends between the _stipites_ and _lora_, and closes the cavity at the back of the head. The back of the tongue in the act of sucking can be formed into a tube through which, partly, probably by capillary action, partly by the pumping action caused by the dilating and contracting of certain parts of the mechanism, the liquid food is drawn up into the aesophagus. This, I believe, has been shown to be the principle on which all bees, short- or long-tongued, suck up their honey.

The subject could be treated at much greater length, and many other structures connected with the mouth parts discussed, but more minute details are unnecessary in an elementary work such as this, and I have therefore limited myself to a description of the broad principles of the process.

{77}