^SSS^ffl?!! fi'> Library Illinois state WRllIORYOFNllTURllLHISW, URBANA, ILLINOIS. .rtOf. THE HUMBLE-BEE MACMILLAN AND CO., Limited LONDON • BOMBAY • CALCUTTA MELBOURNE THE MACMILLAN "company NEW YORK • BOSTON • CHICAGO DALLAS • SAN FRANCISCO THE MACMILLAN CO. OF CANADA, Ltd. TORONTO s.\ .-•<,.ar'*?,>i^v,/i (JUEEX OF BOMBUS TEKKESTR/S INCUBATlNd HKR BROOD. (See page 139.) THE HUMBLE-BEE ITS LIFE-HISTORY AND HOW TO DOMESTICATE IT WITH DESCRIPTIONS OF ALL THE BRITISH SPECIES OF BOMB US AND PSITHTRUS BY F. W. L. SLADEN FELLOW OF THE ENTOMOLOGICAL SOCIETY OF LONDON AUTHOR OF ' QJtJEEN-REARING IN ENGLAND ' ILLUSTRATED WITH PHOTOGRAPHS AND DRAWINGS BY THE AUTHOR AND FIVE COLOURED PLATES PHOTOGRAPHED DIRECT FROM NA TURE MACMILLAN AND CO., LIMITED ST. MARTIN'S STREET, LONDON 1912 COPYRIGHT PREFACE The title, scheme, and some of the contents of this book are borrowed from a little treatise printed on a stencil copying apparatus in August 1892. The boyish effort brought me several naturalist friends who encouraged me to pursue further the study of these intelligent and useful insects. Of these friends, I feel especially indebted to the late Edward Saunders, F.R.S., author of The Hymen- optera Aculeata of the British Islands, and to the late Mrs. Bright wen, the gentle writer of Wild Nature Won by Kindness, and other charming studies of pet animals. The general outline of the life-history of the humble-bee is, of course, well known, but few observers have taken the trouble to investigate the details. Even H offer's extensive monograph. Die Htinimeln Steiermarks, published in 1882 and 1883, makes no mention of many remarkable particulars that I have witnessed, and there can be no doubt that further investigations will reveal more. V vi THE HUMBLE-BEE An article entitled '' Bombi in Captivity and Habits oi Psithyims'' that appeared in the Entomo- logist's Monthly Magazine for October 1899, con- tained my original division of the species of Boinbus into pollen-storers and pocket-makers, and gave accounts of the self-parasitism of certain species, and of the parasitism of B. teri'estris upon B. lucorttvi. Among matter now published for the first time are particulars of the Sladen wooden cover for artificial nests, and details of my humble-bee house. By the employment of the covers anybody may attract humble-bees to nest in his garden, and by obtaining a little wooden house and furnishing it as directed, one may study at leisure and in comfort all the details of their interesting and intelligent ways. The study of humble-bees has hitherto been hampered by the difficulty, encountered even by experienced entomologists, in separating some of the species. It is hoped that the colour-photographs, used in conjunction with the descriptions given, will now remove this difficulty. My thanks are due to Messrs. L. S. Crawshaw, J. W. Cunningham, Geo. Ellison, P. E, Freke, A. H. Hamm, W. H. Harwood, Rev. W. F. Johnson, Rev. F. D. Morice, Messrs. E. B. Nevinson, H. L. Orr, and Rupert Stenton for information kindly supplied about the distribution col ■X OS PREFACE vii of the rarer species and varieties in different parts of the kingdom, and, in many cases, for the gift or loan of specimens. I desire also to acknowledge the kind help of the officials of the British Museum and of the Irish National Museum in granting me every facility for examining specimens in these national collections. F. W. L. SLADEN. Ripple, Dover, Fe^. 5, 19 1 2. CONTENTS PAGE I. Introduction .... I II. Life-history of Bombus 12 HI. PSITHYRUS, the USURPER-BEE 59 IV. Parasites and Enemies of the Humble-Bee 73 V. Finding and taking Nests 83 VI. A Humble-Bee House 94 VII. Domestication of the Humble-Bee 102 Attracting Queens to occupy Artificial Domiciles 104 Getting Queens to breed in Confinement. 130 Placing Queens in Empty Nests . 136 Complete Domestication 139 VIII. How to distinguish the British Species 143 Preliminary Remarks 143 Table of the British Species 152 Bombus lapidarius 154 ,, terrestris 158 ,, lucorum 160 „ soroensis 162 „ pratorum 165 ,, jonellus 167 ,, ,, var. nivalis 168 ,, lapponicus 169 „ cullumanus 171 ,, ruderatus 173 „ hortorum 179 „ latreillellus 182 „ distinguendus . 187 THE HUMBLE-BEE VIII. How TO DISTINGUISH THE BRITISH SPECIES {contd.) . Bombus derhamellus 189 „ sylvarum 191 „ agrorum 193 „ helferanus 195 „ muscorum 197 ,, ,, var. smithianus 200 „ pomorum 201 Distinction between Bombus and Psithyrus 203 Psithyrus rupestris 206 ,, vestalis 208 ,, distinctus 210 ,, barbutellus 214 „ campestris 216 ,, quadricolor 218 IX. On MAKING A COLLECTION . 220 X. Anecdotes and Notes 225 " Number 30 " 225 A Foster-mother 232 An Observation Nest in my Study 237 Observations on Psithyrus 251 A Crippled Terrestris Queen 259 Miscellaneous Notes 262 Additional Notes .... 273 Index ...... 279 ILLUSTRATIONS A pet queen of Bonibus terrestris incubating her brood Frontispiece 1 . Wing-hooks of Bonibus muscorwn .... 2. Antenna-cleaner in fore-leg ..... 3. Diagram of commencing nest .... 4. Hairs of humble-bee, magnified .... 5. Pollen- collecting apparatus in hind-legs of queen and worker humble-bee ...... 6. Honey -pot from nest of Bonibus lapidarius, seen from above ........ 7. Honey-pot from nest of Bonibus lapidarius, side view 8. Eggs, larvs, and pupae of Bombus tc7-restris . 9. Nest of B. terrestris, showing groove in which queen sits 10. Diagram of the initial stages of the humble-bee's brood 11. Comb of i?. lapidarius, showing two honey-pots brimful of honey ....... 12. Comb oi B. lapidarius, showing group of half-full honey pots and irregular clusters of worker cocoons 13. Comb oi B. lucorum, showing pollen-pots and honey-pots 14. Comb of j5. agroruni, showing pollen-pockets . 15. Caterpillar of Aphomia sociella; larva and puparium of Brachyconta devia ; larvae of Volucella bonibylans larva of Fannia ...... 16. Sphcerularia bonibi ...... 17. '^esX. oi Bonibus /lelferanus ..... 18. Plan of Sladen's humble-bee house xi 9 10 19 20 26 26 28 30 33 38 39 41 42 74 80 91 94 xii THE HUMBLE-BEE FIG. 19. Vertical section through a domicile in Sladen's humble- bee house . . . . . . . -95 20. The sections or storeys shown separately ... 96 2 1 . Comb of B. terrestris from Sladen's humble-bee house . i o i 22. Section of Sladen's original device to attract underground- nesting humble-bees ...... 105 23. Sladen's domicile for humble-bees, with Sladen's wooden cover . . . . . .109 24. Vertical section of Sladen's tin domicile . . . .113 25. External anatomy of ^. r/^^i?rrt///j . . . .145 26. Hind metatarsus oi B. terrestris (male), B. lucorum (male), B. soroensis (male), and B. pra forum (male) . . 163 27. Queen oi B. latreillelltis incubating her immense lump of brood . . . . . . . .185 28. Diagram of cocoons in a commencing nest of B. der- haineUiis . . . . . . . .190 29. Y\^\VidiAe.% oi Bontbus zxiA Psithyrus i&vc\2\& . . . 203 30. Tip of abdomen (under-side) of the queens of each of the British species oi Psithyriis, showing the elevations on the 6th ventral segment ..... 3 1 . Antennae of Ps. vestalis $ and Ps. disihicttis $ 32. Device for excluding ants from humble-bee's nest How to hold a humble-bee ..... OJ 34. Loads of pollen collected by Boinbi 204 21 1 229 266 274 PLATES I. Bombus terrestris — queen, worker, and male. To face p. 158 „ lucorum „ „ ,, lapidarius „ ,, „ soroensis ,, ,, II. Bombus pratorum — queen, worker, and male. To face p. 172 ,, lapponicus „ „ ,, jonellus ,, „ „ cullumanus — male {slightly faded). ruderatus — two dark males, three dark queens. , ILLUSTRATIONS xiii III. Bombiis riideraiiis — yellow-banded queen, worker, and male. ,, kortoruin — queen, worker, and male. To face p. 182 ,, laireillellus „ „ ,, distingiiendus ,, ,, IV. Bombus derhamellus — queen, worker, and two males. ,, sylvartan — queen, worker, and male. To face p. 192 ,, agrorwn — three queens, two workers, and two males of various colour patterns. „ helferanus — queen, worker, and male. ,, mils cor w)i ,, ,, V. Psithyrus rupestris — queen and male. To face p. 206 ves talis ,, distinct lis , , barbiitelhis ,, campestris — light queen, light male, and dark male. quadricolor — queen, male. VI. Male armatures of all the British species of Bombiis and Psithyrus. P- 2 7 1 All the specimens shown in the plates are British, except the worker of Bombus soroensis^ which is from the Caucasus Mountains, and differs from British specimens in having the yellow on the abdomen extending farther on the ist segmen.t. A millimetre scale is shown on page 154. INTRODUCTION Everybody knows the burly, good-natured bumble- bee. Clothed in her lovely coat of fur, she is the life of the gay garden as well as of the modestly blooming wayside as she eagerly hums from flower to flower, diligently collecting nectar and pollen from the break to the close of day. Her methodical movements indicate the busy life she leads — a life as wonderful and interesting in many of its details as that of the honey-bee, about which so much has been written. Her load completed, she speeds away to her home. Here, in midsummer, dwells a populous and thriving colony of humble-bees. The details of the way in which this busy community came into being, what sort of edifice the inhabitants have built, how they carry out their duties, and what eventually will become of them will be explained later : it is enough at present to note that the colony, like a hive of honey-bees, consists chiefly of workers, small modified females, whose function in life is not to give birth but to labour for the establishment, bringing home and depositing in cells load after 2 THE HUMBLE-BEE i load of sweets, their only relaxation from this arduous toil being domestic work, such as tending the young, building the comb, and keeping the nest clean and tidy. The supposition that the humble-bee worker is less industrious than the honey-bee is erroneous : she labours with the same zeal and tireless energy, never ceasing until, worn out, she fails one day to return home, and, becoming drowsy and senseless, passes out of existence in the cold of the succeeding night. It is true that in a colony of humble-bees the workers are not nearly so numerous as in a bee-hive, but it is some compensation that they are of a larger size than honey-bees, that they begin field - work at an earlier age, that their hours of labour are longer, commencing earlier in the morn- ing and continuing until later at night, and that they are more hardy, minding less the spells of wind and rain, cloud and cold from which no English spring or summer is free. One gets a good idea of the ceaseless industry of a colony of humble-bees by watching for a while the mouth of the hole leading to the domicile. Though the total population may not exceed one or two hundred, a minute seldom goes by without several departures and arrivals, and two bees will often return together or pass one another : almost all the returning bees have their hind legs laden with pollen and their abdomens distended with nectar. Fanciful writers have likened a colony of bees to a kingdom or city : in reality it is an ordinary family. INTRODUCTION 3 although a large one. There is the mother, whom we call the queen ; and who lays the eggs. Her daughters, the workers, do not become independent as soon as they are old enough to be useful, but, as has been remarked, devote their energies to sup- porting the family and rearing their younger brothers and sisters. One of the peculiarities of the bee family is that all the work is done by the female members. The father has died long before his children are born. The sons are idle, contributing nothing to the stores of the colony ; in the honey-bees' family they are maintained entirely at the expense of the colony, and, when food grows scarce, they are turned out to die, but the humble-bee drones maintain themselves, quietly taking their departure from the nest as soon as they are able to fly. By far the most interesting individual in the humble-bee family is the queen, because of the very eventful life she leads. At first her duties include those of the workers, her brood depending upon her for everything — food, warmth, and protection from enemies. She nurses it with as much motherly devotion, industry, and patience as we see displayed by many birds and mammals in the care of their young : she thus shows much greater capacity and higher intelligence than the queen honey-bee, who, fed and attended by workers throughout her life, is not only incapable of providing for herself, but pays no attention whatever to her offspring, and is merely a machine for laying eggs in enormous numbers. The humble-bee and the honey-bee are the only 4 THE HUMBLE-BEE i bees in the temperate zone that produce workers and dwell in communities. The true humble - bees comprise the genus Bombus.^ Seventeen different species of them are found in the British Isles. In addition, there are six British species of the genus Psithyrus," com- prising the parasitic humble-bees. Most of the British species of humble-bees are black with bright yellow bands, which, however, are sometimes absent, and with a white, orange, or red tail. The remaining species are more or less yellow or tawny. Humble-bees are essentially inhabitants of the north, and they flourish best at about the latitude of Britain. Europe, Central Asia, and North America are well populated with them, especially the moun- tainous regions. Even in Greenland, Alaska, and other dreary tracts in the far north, where the summer is too short for the existence of honey-bees, a few species are to be found, working diligently during the light nights. " Others," in the words of Shuckard, " occur far away to the north of east, booming through the desolate wilds of Kamtchatka, having been found at Sitka, and their cheerful hum is heard within the Arctic Circle as high as Boothia Felix, thus more northerly than the seventieth ^ Greek ^o/x^os (Latin bomhiis), humming, buzzing. Dr. Feltoe lias kindly called my attention to an interesting passage in Theokritos [Idyll m. 12 ff.): "Would I were a humming-bee (^ofxIBevcra ixeXiacra), and could enter thy cave, penetrating the ivy and the fern under which thou dost conceal thyself." But /3oyU^ii\t6s was the word usually employed for the humble-bee, e.g. by Aristo- phanes, Wasps, 107, and by Aristotle, Hist. Anini. ix. 40 and 43. - Pronounced /j/'/Zz/rMJ. From Greek \l/i6vpos, whispering, twittering, per- haps in allusion to their softer hum. INTRODUCTION 5 parallel. They may perhaps with their music often convey to the broken-hearted and lonely exile in Siberia the momentarily cheering reminiscence of joyful youth, and by this bright and brief in- terruption break the monotonous and painful dul- ness of his existence, recalling the happier days of yore." ^ In the Himalayas they are to be met with at all altitudes from 2,000 to over 12,000 feet. But in the plains of India there are none, nor do they exist in Africa, except along the north coast, and Australia and New Zealand have no native species. Where they occur in the tropics they are generally confined to the mountains, although Brazil has a few indolent- looking species. It is safe to say that the total number of species, i.e. of forms that do not interbreed, exceeds a hundred, and that the lesser varieties amount to more than a thousand. It is charming to watch a populous colony of humble-bees busy on its comb, each individual wearing the beautiful livery of its particular species. Each species has its own peculiarities of habit and disposition, so that even in the British fauna there are plenty of different natures to study. Investigating the habits of humble-bees, and experimenting in different ways with them, has been a source of great pleasure to me since boyhood. Colonies have been kept under observation in arti- ficial domiciles ; the ins and outs of their lives have 1 British Bees, by W. E. Shuckard, iS68, page 78. 6 THE HUMBLE-BEE thus been laid bare, and their requirements, which are quite different from those of the honey-bee, have been studied and supplied. In addition, various attempts have been made with queens to establish the colonies artificially ; these have been partially successful, and have revealed several interesting facts about humble-bees, especially re- specting their adaptability to treatment and their intelligence. Only a very few of the numerous queens that set out in the spring with so much promise succeed in establishing colonies. Their failure is due not so much to unfavourable weather as to the attacks of enemies. In its early stages the brood is very liable to be eaten by ants or mice : when this danger is past a humble-bee of the idle genus Psithyrtis may enter the nest, kill the queen, and make slaves of her children ; at a still later period the brood may be consumed by the caterpillars of a wax-moth. As soon as any of these foes have found and entered the nest there is no escape for the inhabitants from destruction, and it has given me a good deal of pleasure to try and protect the bees that have been under my care from them. It may be asked : Can humble-bees be made to produce honey for human consumption ? Under favourable conditions humble-bees store honey, the flavour of which, as most schoolboys know, is excellent ; but, unfortunately, the amount in each nest never exceeds a few ounces, so that to obtain a quantity many colonies would have to be kept, I INTRODUCTION 7 and even then the work of collecting it would be laborious. The tongue of the humble-bee is much longer than that of the honey-bee, consequently she can extract honey from flowers having long narrow tubes, such as red clover, honeysuckle, and hore- hound, which are seldom or never visited by honey-bees. As a rule these flowers are very melliferous. Indeed, the heads of the red clover contain more honey than almost any other flower, a fact appreciated by children, who pull out the tubes and suck them. Humble-bees have almost a mono- poly of the vast amount of honey that is produced in a red clover field, but there are not enough of them to gather much of it. Nevertheless humble-bees are extremely valu- able for fertilising the numerous flowers that they frequent. Whole groups of plants bearing long- tubed flowers, including many species valuable to man, depend chiefly upon humble-bees for their propagation. Charles Darwin, in the Origin of Species, said : " I find from experiment that humble- bees are almost indispensable to the fertilisation of the heartsease ( Viola tricolor), for other bees do not visit this flower." In consequence of the absence of humble-bees in New Zealand it was found that tho red clover did not produce seed freely. So in November and December 1884 a number of queens were sent from England to that country, with the result that two species, B. terrestris and B. ruderatus, have become established there, and 8 THE HUMBLE-BEE i the red clover now yields a plentiful crop of seed. Unfortunately, B. terrestris has a trick of biting holes in such flowers as the broad-bean, snapdragon, and foxglove, close to the honey-glands, to abstract the honey. This, in New Zealand, has resulted in damage to the seed-vessels of certain flowers, and the seed-growers there would now be glad to have this species supplanted by another. The world, which to us consists of sights and sounds, to the humble-bees is made up mainly of scents. I can find no evidence that they hear any- thing at all. It is true they can see near objects, and are expert at distinguishing flowers by their colours ; but darkness prevails inside the nest, and here everything is perceived, so far as one can tell, by the senses of smell and touch, both of which are conveyed through the antennae, these organs being in constant motion, investigating any object to which attention is being paid, whether it be honey, pollen, brood, comrade, or nest material. It cannot be doubted that these and many other things that have little or no smell to us are recognised by their different odours. Humble-bees can readily dis- tinguish the smell of their own species -and that of other species with which their lives are connected in places that have been frequented by them, and B. terf'estris is almost as quick as the honey-bee to discover honey or syrup. They resent, with angry buzzing, the least whiff of human breath in their nest, so the observer should breathe through a corner of his mouth, a habit easily acquired. Yet, I INTRODUCTION 9 in the case of most species, if the nest is uncovered cautiously, the moving of the material and the sudden flood of light appear not to be noticed, though the bees gradually realise that something is wrong, and, if left long exposed, will run off in search of material with which to re-cover the nest. Humble-bees possess, in common with other Fig. I. — A, Portion of posterior margin of fore-\ving of Bombus muscorum queen, seen from beneath. B, Corresponding anterior margin of hind-wing, seen from above. bees, various peculiarities of structure adapted for special uses that it is hardly within the scope of this monograph to describe in detail, but a few of the most interesting may be here referred to. First may be mentioned the wing-hooks, and I cannot do better than quote Bingham's description of these : " The winged hymenoptera are, as a rule, capable of sv/ift and sustained flight. For this purpose they possess a wonderful arrangement (one of the most beautiful in nature) for linking together, during flight, the fore- and hind-wings. Examined lO THE HUMBLE-BEE with a good lens, the fore- wing is seen to have a fold along its posterior margin, while on the anterior margin of the hind -wing a row of hook- shaped bristles or hairs can be easily detected. When the wings are expanded these hooks catch on firmly to the fold in the fore-wing, and the fore- and hind- wing on each side are enabled to act in concert, having the appearance and all the firmness of a single membrane."^ In the humble-bees the wing- FiG. 2. — Antenna-cleaner in fore-le£ hooks number from 17 to 24. Their position is indicated in Fig. 25, p. 145. Another remarkable structure is an antenna- cleaner in the front legs. This consists of a semi- circular incision in the metatarsus, fringed with a fine comb. When the leg is flexed a knife-like spine hinging from the tibia can be made to shut down over the incision. Thus a hole is formed through which the antenna is frequently drawn to rid it of any pollen grains or particles of dust that may have clung to it, ^ Fauna of British India — Hymaioptera, by C. T. Bingham, 1897, vol. i. pp. viii and ix. INTRODUCTION ii The tongue (Fig. 25, p. 145), using the term in its wider sense, is a complex structure consisting of an outer and an inner pair of sheaths, the maxillae and the labial palpi, which enclose the true tongue, this being in the humble-bee and its allies a long hairy organ having a groove on its under side. The honey is sucked up by the dilatation and contraction of the groove and of the tube made by the sheaths around the tongue. When not in use the whole apparatus is neatly folded away under the head. Humble-bees breathe, not as we do through openings in the head, but through small holes in the sides of the body, called spiracles, of which there are two pairs in the thorax and five pairs (in the male six) in the abdomen. The spiracles of the thorax, which are situated under the wings, contain a vocal apparatus which is the source of the buzzing sound made by the humble-bee when it is irritated. Just inside the spiracle the windpipe is enlarged to form a sounding-box, and the sound is produced by the air expired passing over the edge of a curtain- like membrane fixed across the mouth of the sound- ing box. During the buzzing the wings, it is true, vibrate or quiver and increase the sound, but if they are removed the sound is still produced, while if the thoracic spiracles are covered, as Burmeister showed, the buzzing ceases or becomes so feeble that it is scarcely perceptible. Other organs will be considered as occasion arises. II LIFE-HISTORY OF BOMBUS The story of the life of the humble-bee is largely that of the queen. From start to finish she is the central and dominating personage upon whose genius and energy the existence of the race depends. For she alone survives the winter, and, unaided, founds the colony in which she takes the position of its most important member. The queen is raised in company with many others in July or August, the rearing of the queens being the final effort of the parent colony. Fertilisation is the first important event in the queen's life. This takes place in the open air as a rule, but there are good reasons for supposing that it can be accomplished within the nest. The young queens are shy and show themselves very little. The males course up and down hedgerows, or hover over the surface of fields and around trees, in the hope of finding their mates. Each species has its particular kind of hunting-ground. If, on a warm day in the month of July, one takes up a position, out of the wind, in a partial LIFE-HISTORY OF BOMBUS 13 clearinof in a wood, near some bushes or trees, one is almost sure to see now and then a humble-bee fly swiftly by and enter a dark hollow under a tree or shrub, where it pauses for a second, almost alighting, and then passes out and proceeds to another recess, where it again pauses and almost alights. Each succeeding bee flies in the same direction and visits the same spots. If these bees be caught, it will be found that they are all males ^ith^r o{ B . pratorum or B. hortoritm. This strange behaviour ot the male humble-bee has puzzled many observers, but I have noticed certain facts about it that point to an explanation. A sweet fragrance, like the perfume of flowers, is perceptible about the pausing places. This same fragrance may be detected in the scent produced by a male if he be caught in the fingers, although it is now blended with an odour like that of sting-poison emitted In fear. Evidently, therefore, the males emit the perfume in their pausing places ; and I think it extremely likely that in doing so they attract not only one another, but the queens. The males of the one species do not pause at spots frequented by those of the other species, and we may infer from this that each species emits a different scent. The males of all the species are more or less fragrant when captured, those of B. latreillelliis and B. distinguendus being especially so. The scent, I find, proceeds from the head, probably from the mouth. At the end of August 19 10, my study 14 THE HUMBLE-BEE n was most pleasantly perfumed day after day by the males in a nest of B. Iapida7'his that was standing on a table there. The males of B. derhamellus often disport them- selves around the nest, waiting for the queens to come out ; those of B. latreillelhis will also do this ; and I have seen a male of B. rudej-atus ride away upon a queen as she was flying from the nest.^ Immediately after fertilisation the queen seeks a bed in which to take her long winter sleep. The queens of some of the species hibernate under the ground, others creep into moss, thatch, or heaps of rubbish. I have found B. lapidarins and B. terresh'is and occasionally B. rtideratus and B. latreillelhis in the ground, B. lucoriun and B. hor- torum in moss, and B. pratorum sometimes in the ground, sometimes in moss. My observations have been made chiefly on the underground-hibernating species, lapidarins and terrestris. Both species pass the winter in much the same situations, but terrestris likes best to burrow in ground under trees, while lapidarius prefers a more open position, almost invariably ^ The Rev. A. E. Eaton observed the males of B. nieiidax in the Berner Oberland, at an altitude of over 6000 feet, "resorting to favourite spots to bask (a stone or a spot of bare ground), hovering with a gradual fall like a feather, that ends almost imperceptibly in a dead stop, and standing with wings half spread, ready to dart off in an instant at the least alarm, or the sight of any insect flying past." E. Saunders, in quoting this in the Ento- tiiologist's Monthly Magazine (April 1909, p. 84), called attention to the enormous eyes of the male of B. niendax, and to the fact that the males of the sand-wasp Asiatus, whose eyes are so large that they unite, have exactly the same habit. II LIFE-HISTORY OF BOMBUS 15 choosing the upper part of a bank or slope facing north or north-west, though generally near trees. In such banks I have sometimes found great numbers of queens, chiefly lapidarius, and it is easy to discover them, because in burrowing into the ground each queen throws up a little heap of fine earth, which remains to mark the spot until the rains of autumn wash it away. The burrows are only one to three inches long, and if the bank is steep they run almost horizontally. They are filled with the loose earth that the queen has excavated. The queen occupies a spherical cavity having a diameter of about i^ inch. It is evidently damp and not cold that the queens try to avoid. Indeed, the northern aspect shows that they prefer a cold situation, and the reason is easily guessed. The sun never shines on northern banks with sufficient strength to warm the ground, so that the queens do not run the risk of being awakened on a sunny day too early in spring, for the queen humble-bee is very susceptible to a rise in temperature in the spring, although heat in autumn, even should it amount to 80° F,, will not rouse her when once she has become torpid. The queen easily takes fright while she is excavating her burrow, and I find that many burrows are begun and not finished. The queen always fills her honey-sac with honey before she retires to her hibernacle. This store of liquid food is no doubt essential for the preservation of life, and is especially needed, one would think, i6 THE HUMBLE-BEE during September, when the ground is often very dry and warm. Although the young queens may sometimes be seen flying in and out of the parent nest, I find that the majority of them leave it for good on their first day of flight ; and as they are only occasionally ob- served gathering nectar from the flowers, I think that many, having filled themselves with honey before they leave the nest, become fertilised on the same day and immediately afterwards seek their winter quarters. During the first few weeks the queen sleeps lightly, and if disturbed, for instance, by a visit from an earwig, she wakes up, creeps out of her burrow and flies away ; but when the weather grows cold she folds her legs and bends as in death, sinking into deep torpor, from which she is not easily aroused. The period of torpor lasts about nine months. Early species that commence sleeping in July, such as B. pratoruin, are astir as soon as March and April, while later kinds wait until May and even June. On sunny days in March the queens oi prat or urn, terrestris, and other hardy species may be seen busily rifling the peach-blossom, willow catkins, and purple dead-nettle, but in the afternoon as the sun descends and the air grows chilly they creep into hiding- places, where they relapse into semi-torpor, remaining in this condition until a favourable day again rouses them into activity. LIFE-HISTORY OF BOMBUS 17 The weather improving, the periods of animation become more frequent and last longer. Now each queen sets to work to search for a nest in which to establish her colony. The nest is usually one that has been made and afterwards vacated by a field- mouse, vole, or other small mammal, and consists of fine soft fragments of grass or moss, or it may be leaves, woven into a ball with a small cavity in the middle. Most of the species choose a nest that is under the ground, access to which is obtained by a tunnel varying in length from a few inches to a yard or more, but generally about two feet. The remaining species dwell in nests on the surface of the ground hidden in thick grass or under ivy ; these are often called " carder-bees " because they collect material from around the nest and add it to the nest, combing it together with their mandibles and legs. But some of the underground-dwelling species occasionally occupy nests on or near the surface, often in strange situations, such as under boxes or in old birds' nests, rotten stumps, or out- houses, while some of the surface-dwelling species are sometimes found inhabiting nests under the ground, reached by a short tunnel. In places where there is much moss or soft dead grass the carder-bee queen may sometimes construct the entire nest herself. It often happens that the mouths of the holes leading to the underground nests are overgrown with grass or ivy and half closed with debris, consequently they are not easily discovered, and the queens of the underground- i8 THE HUMBLE-BEE n nesting species may be seen throughout the spring hovering over the ground in woods and meadows making a diligent search for them ; now and then the queen ahghts in a promising-looking spot and makes a closer examination of the ground on foot. Having found a suitable nest, the queen becomes rather excited and visits it frequently. Her first flight from her new home is a momentous one, for from it she has to learn how to find her way back again to it. Having accustomed herself to the ap- pearance of the entrance by crawling around it, she ventures to take wing and poises herself for a moment facing the entrance. Then she rises slowly, and, taking careful notice of all the surroundings, de- scribes a series of circles, each one larger and swifter than the last. So doing she disappears, but soon she returns and without much difficulty rediscovers the entrance. Similar but less elaborate evolutions are made at the second and third departures from the nest, and soon her lesson has been learnt so well that her coming and going are straight and swift. She now spends a good deal of time in the nest, the heat of her body gradually making its interior perfectly dry. If the nest has been long unoccupied and is in bad repair, she busily sets to work to reconstruct it by gathering all the finest and softest material she can find into a heap, seizing and pulling the bits of material with her jaws and passing them under her body backwards with her middle and hind pairs of legs ; then she creeps into the middle of the heap and makes there a very snug and warm cavity, LIFE-HISTORY OF BOMBUS 19 measuring about an inch from side to side but only about five-eighths of an inch from top to bottom, with an entrance at the side just large enough for her to pass in and out. In the centre of the floor of this cavity she forms a little lump of pollen-paste, consisting of pellets made of pollen moistened with honey that she has collected on the shanks (tibiae) of her hind legs. These she moulds with her jaws into a compact pollen and e^y6 ey-pot /ioneypol pollen and e.q^s Fig. 3. — Diagram of commencing Nest. mass, fastening it to the floor. Upon the top of this lump of pollen she builds with her jaws a circular wall of wax, and in the little cell so formed she lays her first batch of eggs, sealing it over with wax by closing in the top of the wall with her jaws as soon as the eggs have been laid. The whole structure is about the size of a pea.^ The method of collecting the pollen employed by the humble-bee and honey-bee, and the apparatus on the legs for carrying it out, are very wonderful and interesting ; and as an essential part of the ^ I think it likely that the eggs are sometimes laid in two lots, separated by an interval of a day or two. Their number varies from 8 to 16 ; generally it is about 12. 20 THE HUMBLE-BEE n process is not mentioned in our text-books on bees I will here refer to it at length. Everybody has seen the loads of pollen, some- times called wax in ignorance, on the legs of the bees. The load is carried on the outer side of the tibia or shank, which is concave, smooth, and bare, and fringed around the edge with long stiff hairs which act, as Cheshire observed, like the sloping stakes that the farmer places round the sides of his waggon when he desires to carry hay. This outer side of the tibia with its surrounding wall of hair is called the corbicula or pollen-basket. In some flowers, such as wallflower and red ribes, the pollen is gathered by the mandibles, as noticed by Crawshaw, but in others it collects among the hairs of the body, especi- ally those clothing the thorax and underside of the body, these being branched and thus admirably adapted for retaining it. According to H offer {^Die Huin- ineln Steiertnarks, p. 2,l)i the humble- bee brushes the pollen with the two first pairs of feet out of the body Corbicula hairs forwards to the mouth, there fluff '^'^^ chews and kneads it with honey and Hairs of Humble-bee, its saliva into a sticky paste, lays magnified. \^q\^ ^f jj- again with the feet, and presses it with the help of the middle legs on to the corbicula. But I believe the process is different in an important detail. LIFE-HISTORY OF BOMBUS 21 In the hind-legs, the next joint below the tibia, called the metatarsus, is enlarged into a sub- rectangular plate, which is densely clothed on the corbicula receiver comb auricle Fig. 5. — Pollen-collecting apparatus in Queen and Worker Humble-bee. A. Hind legs of Bombus terrestris queen. B. End view of apex of tibia, showing arch of hairs covering entrance to corbicula. r, receiver ; s, juncture of metatarsus with tibia (this is a ball-and- socket joint, the socket being here shown). C. Diagrammatic section of receiver and auricle, showing method of working, f, comb ; r, receiver ; a, auricle. inner side with stiff bristles forming a brush. In a pollen-collecting honey-bee this brush is filled with moistened pollen, which is evidently on its way to the corbicula. Cheshire states that the metatarsal 22 THE HUMBLE-BEE .i brush of the right leg transfers its pollen to the corbicula of the left leg, and vice versa, but he goes on to say that the transfer is effected by the metatarsus scraping its brush on the upper edge of the tibia/ My own belief is that the pollen is scraped off the metatarsal brush by a comb, situated at the end of the tibia on the inside, into a concave receiver there. When the leg is straightened a pro- jection on the metatarsus called the auricle enters the receiver, compresses the pollen, and pushes it out on to the lower end of the corbicula, where there is a break in the surrounding wall of hair, and plasters it to the mass of pollen already collected in the corbicula. Finally, the metatarsus of the middle leg is used to pat the pollen down on the corbicula. This opinion is supported by (i) the structure of the parts, (2) the fact that when the bees are collect- ing pollen from the flowers they rub their hind-legs together in a longitudinal direction and do not cross them, and (3) an examination I made of the load of a honey-bee, which consisted partly of white and partly of orange-coloured pollen. The orange pollen (which had evidently been gathered last, because the metatarsal bushes were filled with orange pollen) was found only on that part of the corbicula that was nearest to the auricle, where it had been forced in as a wedge between the white pollen and the corbicula, causing the whole mass of pollen to swell .and rise and also to buckle in the middle. The cuter side of the lump of pollen was tinged on the ' Bees a7id Bee-keeping, by F. R. Clieshire, iSSS, vol. i. page 131. II LIFE-HISTORY OF BOMBUS 23 surface with orange, showing where the metatarsus of the middle leg, which bore orange pollen grains, had patted it. The same organs are present in the hind-leg of the humble-bee (see Fig. 5).^ To test the working of the apparatus I placed some pollen in the receiver of a leg of a dead queen of B. lapidarius, and then straightened the leg ; the pollen was at once transferred to the corbicula. When the pollen is being collected it always begins to gather at the lower end of the corbicula, and the reason is now clear. Also the smooth and slippery surface of the corbicula is explained, for the pollen slides up it, as the result of the numerous little contributions delivered on to it by the auricle. The few hairs that obstruct the entrance to the corbicula number about three ; they stand a little distance inside the entrance and are widely separated from one another. They provide a means of attachment for the pollen until the accumulated mass has grown large enough to be supported by the hairs at the sides of the corbicula. The eds^e .of the entrance to the corbicula is densely clothed with fluff (seen under the microscope to be moss-like hairs), which probably serves the same purpose. The surface of the receiver is smooth except 1 In the honey-bee the bristles in the brush of the hind metatarsi are arranged in ten transverse rows, and are about as wide apart as the tips of the teeth of the tibial comb, but in the humble-bee they are not arranged in rows. In many pollen-collecting humble-bees the brush contains only a little dry pollen, and the moisture is confined to its upper corner, which is probably the only part that is much combed by the tibia. 24 THE HUMBLE-BEE h along the margin bordering on the corbicula, where it is finely striate, the little furrows and ridges running in the direction in which the pollen moves. The auricle bears a tuft of hairs which helps to guide the pollen on to the corbicula. Long hairs spring from either side of the entrance to the corbicula and form over it an arch which helps to support the accumulated mass of pollen without interfering with the delivery of fresh pollen from below. The arch is also of service in guiding the pollen on to the corbicula.^ Humble-bees working on the white dead nettle may be seen brushing the pollen out of the hairs on the front of the thorax, where it chiefly gathers, with the middle pair of feet, the instrument used being the metatarsus or basal joint of the foot, which is modified into a brush like the metatarsus of the hind leg. I have occasionally found a minute ball of moistened pollen in the mandibles, which seems to support H offer's view that the pollen is moistened in the mouth. The wax of the humble-bee is much softer and ^ See my paper, " How pollen is collected by the Social Bees, and the part played by the Auricle in the process," in the British Bee Jomnal for Dec. 14, 191 1, and " Further Notes on how the Corbicula is loaded with Pollen," in the B.B.J, for April 11, 1912. In the latter article the receiver is named the excipula {Lat. receptacle), and the entrance to the corbicula the limeii {La/, threshold). In Bombiis confiisus, a native of Central Europe, the obstructing hairs on the limen are reduced to one ; in the honey-bee the fluff on the limen is scanty, and there are no obstructing hairs, except one, situated some way inside the entrance. In the humble-bee the working surface of the auricle is finely rugose, but in the honey-bee it is covered with pointed teeth inclining in the direction that the pollen moves. In Bombiis lapidarius, terrestris, hicoriim, pratorum, lapponicits, latreillcllns, and distingiieiidus the auricle is hairy on the inner si