Ants, bees, and wasps : a record of observations on the habits of the social hymenoptera

Front matter

Plate 1.

1 Fasius mger ^

2. „ fLavus „

Preface

Although the observations of Huber, Fore], McCook, and others are no doubt perfectly trustworthy, there are a number of scattered stories about ants which are quite unworthy of credence ; and there is also a large class in which, although the facts may be correctly recorded, the inferences drawn from them are very questionable. I have endeavoured, therefore, by actual experiments which any one may, and I hope others will, repeat and verify, to throw some light on these interesting questions.

The principal point in which my mode of experimenting has differed from that of previous observers has been that I have carefully marked and watched particular insects ; and secondly, that I have had nests under observation for long periods. No one before had ever kept an ants’ nest for more than a few months. I have one now in my room which has been under constant observation ever since 1874, i.e. for more than seven years.1

1 I may add that these ants are still (August 18S2) alive and well. The queens at least are now eight years old, if not more.

PREFACE.

Vll

I had intended to make my observations principally on bees ; but I soon found that ants were more convenient for most experimental purposes, and I think they have also more power and flexibility of mind.

They are certainly far calmer, and less excitable.

I do not attempt to give anything like a full lifehistory of ants, but I have here reproduced the substance of two Eoyal Institution lectures, which may serve as an introduction to the subject. Many of the facts there recorded will doubtless be familiar to most of my readers, but without the knowledge of them the experiments described in the subsequent chapters would scarcely be intelligible.

I have given a few plates illustrating some of the species to which reference has been most frequently made ; selecting Lithography (as I was anxious that the figures should be coloured), and having all the species of ants drawn to one scale, although I was thus obliged in some measure to sacrifice the sharpness of outline, and the more minute details. I am indebted to Mr.

Vlll

PREFACE.

Bates, Dr. Gunther, ]\Ir. Kirby, and Mr. Waterhouse, for their kind assistance in the preparation of the plates.

As regards bees and wasps, I have confined myself * for want of space to the simple record of my own observations.

I am fully conscious that experiments conducted as mine have been leave much to be desired, and are scarcely fair upon the ants. In them native haunts and under natural conditions, more especially in warmer climates, they may well be expected not only to manifest a more vivid life, but to develop higher powers.

I hope, however, that my volume will at least show the great interest of the subject, and the numerous problems which still remain to be solved.

High Elms, Down, Kent:

Introduction

PAGE

Position of ants in the Animal Kingdom — Ants divided into three families — Number of species — Mode of observation — Nests — Mode of marking ants — Stages in life of ants— Egg, larva, pupa, imago — Length of life — Structure of ants — Head, thorax, abdomen, antennae, eyes, ocelli, mouth parts, legs, wings, sting — Origin of the sting — Character of ants — Wars among ants — Modes of fighting — Queen ants — Workers — Different classes of workers — The honey ant — Soldiers — Origin of the soldiers — Division of labour — Habitations of ants — Communities of ants — Food — Enemies — Character — Industry — Games — Cleanliness . . . . 1

Chapter II. Formation And Maintenance Of Nests

Foundation of new nests — Doubts on the subject — Views of Huber, Blanchard, Forel, St. Fargeau, Ebrard — Experiments with queens- Foundation of a nest of Myrmioa by two queens — Adoption of queens — Fertility of workers — Eggs laid by fertile workers always produce males — Queens seldom produced in captivity — Origin of difference between queens and workers— Longevity of ants — Arrangement of chambers in a nest — Division of labour — The honey ant . . 30

X

Chapter III. On The Relation Of Ants To Plants

PAGE

Flowers and insects — Ants not so important in relation to flowers as bees, but not without influence — Ants seldom promote cross-fertilisation, and hence injurious to flowers — Modes by which they are excluded — Belt — Kerner — Aquatic plants — Moats — Dipsacus — Slippery surfaces — Gentian, snowdrop, cyclamen — Concealment of honey — Antirrhinum, Linaria, Campanula, Ranunculus, Lamium, Primula, Geranium, &c. — Protection of honey by thickets of spines or hairs — Protection by viscid secretions — Silene, Senccio, Linncea, Polygonum, & c. — Milky juice — Lactuca — Nectaries on leaves — -Leaf-cutting ants — Ants as tree guards — Importance of ants in destroying other insects — Harvesting ants— Solomon — The Mischna — Meer Hassan Ali — Sykes — Moggridge — Agricultural ants — Lincecum — McCook 50

Chapter IV. Relations To Other Animals

Hunting ants — The Driver ants — Ecitons — Insects mimicking ants — Enemies of ants — Parisites — Mites — Phora — Domestic animals of ants — Aphides — Eggs of Aphides kept through the winter by ants — Blind beetles — Pets — Progress among ants — Relations of ants to one another — Stenamma — Solcnopsis — Slave-making ants — Formica sanguinca — Polyergus — Expeditions of Polyergus — Polyergus fed by the slaves — Strongylognathus — Degradation of Strongylognathus — Anergates — Explanation of the present state of Strongylognathus and Anergates — Progress among ants — Phases of life — Hunting, pastoral, and agricultural species . . 63

Chapter V. Behaviour To Relations

Mr. Grote on ‘Morality as a necessity of society’ — Behaviour of ants to one another — Statements of previous writers:

CONTENTS.

xi

PAGBJ

Latreille, St. Fargeau, Forel— Difference of character among ants — Experiments — Isolated combats — Neglect of companions if in trouble — Experiments with insensible ants — Drowned ants — Buried ants — Contrast of behaviour to friends and strangers — Instances of kindness — A crippled ant— A dead queen — Behaviour to chloroformed friends — Behaviour to intoxicated friends . . 93

Chapter VI. Recognition Of Friends

Number of ants in a community — They all recognise one another — All others are enemies — Recognition after separation — Strange ants never tolerated in a nest — Experiments — Behaviour to one another after a separation of more than a year — Recognition unmistakable — How are they recognised ?

— Some naturalists have suggested by scent, some by a pass- word — Experiments with intoxicated ants— With pup® removed from the nest and subsequently returned — Separation of a nest into two halves, and recognition as friends by the ants in each half of young bred in the other half — Pup® tended by ants from a different nest treated as friends in the nest from which they were taken, and as strangers if put into the nest of their nurses — Recognition neither personal nor by means of a pass- word . . . .119

Chapter VII. Power Of Communication

Statements of previous writers : Kirby and Spence, Huber, Franklin, Dugardin, Forel — Habit of bringing friends to food — Exceptional cases — Experiments to determine whether ants are brought or directed to stores of food — Scent— Sight — Experiments with different quantities of food — Ants which returned empty-handed and brought friends to assist . 153

CONTENTS.

xii

Chapter VIII. T1ie Senses Of Ants

PAG 3

Sight : — Difficulty of understanding how insects see — Number of eyes — Two theories — Views of Muller, Grenacher, Lowne, Claparede — Appreciation of colour — Sensitiveness to violet — Perception of ultra-violet rays. Hearing : — Antenme regarded by many entomologists as organs of hearing — Opinions as to whether- ants, bees, and wasps hear — General opinion that bees and wasps can hear — Huber and Forel doubt in the case of ants — Experiments with ants— Forel’s observations — Colonel Long — Mr. Tait — Structure of anterior tibia. The Sense of Smell . . .182

Chapter IX. General Intelligence

Statements of previous writers — Economy of labour— Experiments as to ingenuity in overcoming obstacles and economising labour — Experiments with bridges, embankments, and moats — Earthworks — Ingenuity in building nests — Difficulty in finding their way — Experiments with movable objects — Sense of direction — Experiments with rotating disks — Experiments with rotating table — Influence of light 236

Chapter X Bees

Difficulty experienced by bees in finding their way — Communication between bees — Bees do not by any means always summon one another when the}1' have discovered a store of food — Bees in strange hives — Infatuation of bees — Want of affection — Behaviour to queen — Sentinels — The sense of hearing — The sense of colour — Experiments with coloured papers — Power of distinguishing colours — Preference for blue — Influence of bees on the colours of flowers — Blue flowers— Paucity of blue flowers — Blue flowers of comparatively recent origin . . . . 274

CONTENTS.

xin

Chapter XI. Wasps

Communication among wasps — Like bees, they by no means invariably bring companions when they have discovered a store of food — Courage of wasps — Polistes gallica — A tame wasp — Power of distinguishing colours — Wasps less guided by colour than bees — Industry of wasps — A day’s work — Directness of flight of wasps .....

APPENDICES

PAGE

. 437

LIST OF ILLUSTRATIONS.

The sign 3 indicates a worker ; $ a male ; and ? a queen.

PLATE I.

Fig. 1 . Lasius niger 3 . „ 2. „ flavus 3-

„ 3. Formica fusca 3

Fig. 4. Myrmica ruginodis 3 „ 5. Polyergus rufescens 3 •

„ 6. Formica scunguinea 3 •

PLATE II.

Fig. 1. Atta barbara 3 major.

„ 3. Pluidule megacephala 3 major.

Fig. 4. Plicidole megacepkala 3 minor.

„ 5. Formica rufa 3 •

PLATE III.

Fig. 1. (Fcodoma ceplialotes 3 major.

„ 2. CEcodoma ceplialotes 3

minor

Fig. 3. Stenamma Westwoodii 3 „ 4. Solenopsis fug ax 3 .

Fig. 1. Caruponotus infiatus 3 •

„ 2. Tetramori um ccespi-

tum 3 •

PLATE IY.

Fig. 3.

Strong ylognatkus testaceus 3.

Aner gates atratulus 3 .

PLATE Y.

Pig. 1 . Lasius fla vus 2 .

n 3. „ 1. larva.

Fig. 5. Beckia albinos.

6. Aphis.

7. Platyartkrus Hoffman

seggit.

Clavigcr foveolatus.

LIST OF THE

PKINCIPAL BOOKS AND MEMOIRS

REFERRED TO.

Andre, E.

. Desc. des Fourmis d’Europe. Rev. et Mag. de Zool., 1874.

Bates, H. W. .

Belt, T. .

Beet, Paul .

. The Naturalist on the Amazons.

. The Naturalist in Nicaragua.

. ‘ Les animaux voient-ils les mcmes rayons lumineux que nous? ’ Arch, de Physiol, 1869

Blanchard, E.

. Metamorphoses of Insects. Trans, by Duncan.

BUCHNER, L. .

Buckley, S. B.

Physique, vol. i.

. Mind in Animals.

. On Myrmica molefaciens. Proc. Acad. Nat. Sci. Philadelphia, 1860.

Burmeister, H.

Curtis, J.

. Manual of Entomology.

. On the Genus Myrmica. Trans. Linn. Soc., 1864.

Darwin, C.

Delpino, F.

Dewitz, H.

. Origin of Species.

. Suirapporti delleFormiche colie Tettigometre. . Ueber Bau und Entwickelung des Stachels der Ameisen. Zeits. f. Wiss. Zoologie, vol. xxviii

Dujardin, F. .

Edwards, H. .

. Obs. sur les Abeilles. Ann. des Sci. Nat., 1862. . Notes on the Honey-making Ants. Proc. California Acad., 1873.

Elditt, H. L.

Emery, C.

a

LIST OF BOOKS AND MEMOIRS.

Emery, C.

Forel, A.

Gelieu, J. de .

Gould, Rev. W.

Graber, Yitus

Gredleb, Y. .

Grimm

Hagens, Herr von

. Le Formiche ipogei. Ann. Mus. Civ. di St Nat. di Genova.

. Fourmis de la Suisse.

. Le Conservateur des Abeilles.

. Account of English Ants.

. Die Tympanalen-Sinnesapparate der Or* thopteren.

. Der zoologische Garten.

. Die Myrmecophilen. Stettin. Ent. Zeits., 1845. . Ueber Ameisengaste. Berlin. Ent. Zeits., 1865r

Heer, 0.

Huber, P.

Huxley, T. H.

Kerner, Dr. A.

Kirby and Spence Landois, Dr. H.

Ueber Ameisen mit gemisehten Colonien. Berlin. Ent. Zeits., 1867.

. Natural History of Ants.

. On the Reproduction of Aphis. Trans. Linn. Soc., xxii. 1859.

. Flowers aDd their Unbidden Guests. Trans, by Ogle.

Introd. to Entomology.

. Thierstimmen ; also Zeits. fur Wiss. Zool.,

Langstroth, L. L. . Treatise on the Honey Bee.

Latreile, P. . . Hist. Nat. des Fourmis.

Lespes, C. . . Sur les Moeurs de Lomechusa paradoxa. Ann.

des Sci. Nat., 1863.

Lincecum, Gideon . On the Agricultural Ant of Texas. Linn. Journal, 1861.

Long, Col. C. G. . Central Africa.

Lubbock, Sir J. On the Anatomy of Ants. Trans. Linn. Soc., 1879.

„ . Ova and Pseudova of Insects. Phil. Trans.,

„ . Obs. on Ants, Bees, and Wasps. Parts 1-9,

, . On Some Points in the Anatomy of Ants.

Micros. Soc., 1877.

Lund, M . Lettres sur les Habitudes de quelques Fourmis

du Bresil. Ann. des Sci. Nat., xxiii. 1S31.

LIST OF BOOKS AND MEMOIRS.

xix

McCook, H. 0.

. Note on Adoption of a Queen Ant. Proc.

Acad. Nat. Sci. Philadelphia, 1879.

. On the Nat. His. of the Agricultural Ant of

Texas.

>» • Markel, F.

. The Honey Ant of Texas.

. Beit, zur Kenntniss der unter Ameisen lebenden Insecten. Germar’s Zeit. Ent., 1841.

Mate, Dr. G. L.

n •

. Europ. Formiciden.

. Leben und Wirken der einh. Ameisen.

Meinert, F.

Meter, J.

. Ueber conconlose Ameisenpuppen. Stettin Ent. Zeit., 1864.

Muller, P. vV. J.

. Beitrage zur Naturgeschichte der Gattung Claviger. Germar’s Mag. de Zool., 1818.

Ormerod, E. L.

Rambert, M. .

Robert, E.

. Natural History of Wasps.

. Moeurs des Fourmis.

. Observations sur les Moeurs des Fourmis. Ann, des Sci. Nat., 1842.

Roger, J.

. Beit, zur Kennt. der Ameisenfauna der Mittelmeerlander. Berlin. Ent. Zeit., 1867.

St. Fargeau, Lepeletier. Hist. Nat. des Hym6nopt&res. Saunders, Edward Brit. Heterogyna and Foss. Hymenoptera.

Savage, T. S. .

Trans. Ent. Soc., 1880.

. On the Habits of Driver Ants. Trans. Ent. Soc., 1847.

Schenk, Professor

. Beschr. Nassau. Ameisenarten. Stettin. Ent. Zeit., 1858.

Siebold, C. T. von. Ueber das Stimm. und Gehororgan der Or-

Smith, F.

thopteren. Weissmann’s Arch., 1844. . Cat. of Brit. Foss. Hymenoptera.

. Essay on British Formicidae. Trans Ent. Soc., N.S. vol. iii. p. 98.

Sykes, Col.

. Account of Pheidole providens. Trans. Ent. Soc., 1836.

Wesmael, C. .

. Sur une nouv. Esp&ce de Fourmi du Mexique. Bull, de l’Acad. de Sci. de Bruxelles, 1838.

Westwood, J. 0.

. Modem Classification of Insects.

•1

. Obs. on Typhlopone. Ann. Mag. Nat. Hist,, 1841.

ANTS, BEES, AND WASPS.

Chapter I. Introduction

The Anthropoid apes no doubt approach nearer to man in bodily structure than do any other animals ; but when we consider the habits of Ants, their social organisation, their large communities, and elaborate habitations; their roadways, their possession of domestic animals, and even, in some cases, of slaves, it must be admitted that they have a fair claim to rank next to man in the scale of intelligence. They present, moreover, not only a most interesting, but also a very extensive field of study.

Ants are divided into three families : the Formicidae, Poneridae, and Myrmicidse, comprising many genera and a large number of species. In this country we have rather more than thirty kinds ; but ants become more numerous in species, as well as individuals, in warmer countries, and more than a thousand species

B

NUMBER OF SPECIES.

are known. Even this large number is certainly far short of those actually in existence.1

I have kept in captivity about half of our British species of ants, as well as a considerable number of foreign forms, and for the last few years have generally had from thirty to forty communities under observation. After trying various plans, T found the most convenient method was to keep them in nests consisting of two plates of common window glass, about ten inches square, and at a distance apart of from yL- to £ of an inch (in fact just sufficiently deep to allow the ants freedom of motion), with slips of wood round the edges, the intermediate space being filled up with fine earth. If the interval between the glass plates was too great, the ants were partly hidden by the earth, but when tht distance between the plates of glass was properly regulated with reference to the size of the ants, they were open to close observation, and had no opportunity of concealing themselves. Ants, however, very much dislike light in their nests, probably because it makes them think themselves insecure, and I always therefore kept the nests covered over, except when under actual

1 I have had some doubt whether I should append descriptions of the British species. On the whole, however, I have not thought it necessary to do so. They are well given in various entomological works : for instance, in Smith’s Cat. of British Fossoriai Hymenoptera, published by the Trustees of the British Museum ; Saunders’ ‘ Synopsis of British Heterogyna,’ Trans. Entomological Soc. London ; and in Mayr’s Die Ev/rop. Formiciden, all of which are cheap and easily procurable. I have, however, given figures of the principal species with which I have worked.

MODE OF OBSEKVATION.

observation. I found it convenient to have one side of the nest formed by a loose slip of wood, and at one corner I left a small door. These glass nests I either kept in shallow boxes with loose glass covers resting on baize, which admitted enough air, and yet was impervious to the ants ; or on stands surrounded either by water, or by fur with the hairs pointing downwards. Some of the nests I arranged on stands, as shown in

E

JS

E

Cn-J —

Fig. 1.

JJ

J)

^Ti

D

D

n

D

tig. 1. A A is an upright post fixed on a base B B. C C is a square platform of wood round which runs a ditch of water. Above are six nests, D, each lying on a platform E, which oould be turned for facility of observation, as shown in the dotted lines IT and E'. Thus the ants had a considerable range, as they could wander as far as the water ditch. The object of having the platform C C larger than the supports of the nests

ARTIFICIAL NESTS.

was that if the ants fell, as often happened, they were within the water boundary, and were able to return home. This plan answered fairly well, and saved space, but it did not quite fulfil my hopes, as the ants were so pugnacious, that I was obliged to be very careful which nests were placed on the same stand.

Of course it is impossible to force the ants into these glass nests. On the other hand, when once the right way is known, it is easy to induce them to go in. When I wished to start a new nest I dug one up, and brought home the ants, earth, &c., all together. I •then put them over one of my artificial nests, on one of the platforms surrounded by a moat of water. Gradually the outer earth dried up, while that between the two plates of glass, being protected from evaporation, retained its moisture. Under these circumstances the ants found it more suitable to their requirements, and gradually deserted the drier mould outside, which I removed by degrees. In the earth between the plates of glass the ants tunnelled out passages, chambers, &c. (fig. 2, p. 43), varying in form according to the circumstances and species.

Even between the plates of glass the earth gradually dried up, and I had to supply artificial rain from time to time. Occasionally also I gave them an altogether new nest. They seem, however, to get attached to their old homes, and I have still (August, 1882) one community which has inhabited the same glass case ever since 1874.

It is hardly necessary to say that the individual

DIFFEKENCES IN HABITS.

ants belonging to the communities placed on the stands just described, knew their own nests perfectly well.

These nests gave me special facilities for observing the internal economy of ant life. Another main difference between my observations and those of previous naturalists has consisted in the careful record of the actions of individual ants. The most convenient mode of marking them was, I found, either with a small dab of paint on the back, or, in the case of bees or wasps, by snipping off a fragment at the extremity of the wing. This, I need hardly say, from the structure of the wing, gives the insect no pain ; in fact, as it is only necessary to remove a minute portion, not sufficient to make any difference in their flight, they seemed scarcely to notice it. I never found any difficulty in painting bees or wasps ; if they are given a little honey they become so intent that they quietly allow the paint to be applied. Of course too much must not be put on, and care must be taken not to touch the wings or cover up the spiracles. Ants require somewhat more delicate treatment, but with a little practice they could also be marked without any real difficulty.

No two species of Ants are identical in habits ; and, on various accounts, their mode of life is far from easy to unravel. In the first place, most of their time is passed underground : all the education of the young, for instance, is carried on in the dark. Again, ants are essentially gregarious ; it is in some cases difficult to

STAGES IN THE LIFE OF ANTS — EGGS.

keep a few alive by themselves in captivity, and at any rate their habits under such circumstances are entirely altered. If, on the other hand, a whole community is kept, then the greater number introduces a fresh element of difficulty and complexity. Moreover, even individuals of the same species seem to differ in character, and the same individual will behave very differently under different circumstances. Although, then, ants have attracted the attention of many of the older naturalists, — Gould, De Geer, Reaumur, Swammerdam, Latreille, Leuwenhoeek, Huber, — and have recently been the object of interesting observations by Frederick Smith, Belt, Moggridge, Bates, Mayr, Emery, Forel, McCook, and others, they still present one of the most promising fields for observation and experiment.

The life of an ant falls into four well-marked periods — those of the egg, of the larva or grub, of the pupa or chrysalis, and of the perfect insect or imago. The eggs are white or yellowish, and somewhat elongated. They are hatched about fifteen days after being laid. Those observed by me have taken a month or six weeks.

The larvae of ants (PL V. fig. 3), like those of bees and wasps, are small, white, legless grubs, somewhat conical in form, narrowing towards the head. They are carefully tended and fed, being carried about from chamber to chamber by the workers, probably in order to secure the most suitable amount of warmth

LARVA— PUPA.

and moisture. I have observed, also, that they are very often assorted according to age. It is sometimes very curious in my nests to see them arranged in groups according to size, so that they remind one of a school divided into five or six classes.

As regards the length of life of the larvae, Forel supposed1 that those of Tapinoma matured the quickest, and were full-growa in about six or seven weeks. Some of Myrmica ruginodis , however, observed by me, trrned into pupae in less than a month. In other cases the period is much longer. In certain species, Lcisius fiavus, for instance, some of the larvae live through the winter.

“When full grown the larvae turn into pupae (PL V. fig. 4), sometimes naked, sometimes covered with a silken cocoon, constituting the so-called ‘ ant-eggs.’ We do not yet understand why some larvae spin cocoons, while others remain naked. As a general rule, the species which have not a sting, are enveloped in a cocoon, while those which have, are naked. Latrielle was the first to observe that in one species (F. fusca ) the larvae sometimes spin a cocoon, and sometimes remain naked. The reason for this difference is still quite unknown. After remaining some days in this state they emerge as perfect insects. In many cases, however, they would perish in the attempt, if they were not assisted ; and it is very pretty to see the older ants helping them to extricate them-

1 Los Fuurtrm do la Suisse, p. 420.

PUPA— IMAGO.

selves, carefully unfolding their legs and smoothing out the wings, with truly feminine tenderness and delicacy. Our countryman Gould long ago mentioned, and the fact has since been fully confirmed by Forel, that the pupae are unable to emerge from the cocoons without the assistance of the workers. The ants generally remain from three to four weeks in this condition. *!

In the case of ants, as with other insects which pass through similar metamorphoses, such as bees, wasps, moths, butterflies, flies, and beetles, &c., the larval stage is the period of growth. During the chrygalis stage, though immense changes take place, and the organs of the perfect insect are more or less rapidly developed, no food is taken, and there is no addition to the size or weight.

The imago or perfect insect again takes food, but does not grow. The ant, like all the insects above named, is as large when it emerges from the pupa as it ever will be, though the abdomen of the females sometimes increases in size from the development of the eggs.

We have hitherto had very little information as to the length of life in ants in the imago, or perfect, state. So far, indeed, as the preparatory stages are concerned, there is little difficulty in approximately ascertaining the facts ; namely, that while in summer they take only a few weeks, in some species, as our small yellow meadow ants ( Lasius Jlavws ), the autumn larvae

LENGTH OF LIFE.

remain with comparatively little change throughout the winter. It is much more difficult to ascertain the length of life of the perfect insect, on account of their gregarious habits, and the difficulty of recognising individual ants. I have found, however, as we shall presently see, that their life is much longer than has been generally supposed.

It is generally stated in entomological works that the males of ants die almost immediately. No doubt this is generally the case. At the same time, some males of Myrmica ruginodis, which I isolated with their mates in August 1876, lived until the following spring; one of them till May 17.

It has also been the general opinion that the females lived about a year. Christ 1 indeed thought they might last three or even four seasons, but this was merely a suggestion, and Forel expressed the general opinion when he said, ‘ Je suis persuade qu’en automne il ne reste presque plus que les ouvrieres ecloses pendant le courant de l’ete.’ The average life of a queen is also, he thinks, not more than twelve months. I have found, however, that the life of the queens and workers is much longer than had been supposed. I shall give further details in a subsequent chapter, but I may just mention here that I have now (August 1882) two queens which have lived with me since the year 1874. They must therefore be at least eight years old, and seem still quite strong and

1 Naturgoichichte der Imckten.

STRUCTURE OF ANTS.

well. They continue still (1882) to lay a few egg.?, which, I may add, produce workers.1

I have also some workers which I have had since 1 875.

The body of an ant consists of three parts : the head, thorax, and abdomen. The head bears the principal organs of sense, and contains the brain, as the anterior portion of the nervous system may fairly be called. The thorax, ^supporting the legs and, when they are present, the wings, contains the principal muscles of locomotion. The abdomen contains the stomach and intestines, the organs of reproduction, the sting, &c.

Returning to the head : the antennae consist of a short spherical basal piece, a long shaft, known as the scape, and a flagellum of from six to seventeen (generally, however, from ten to thirteen) short segments, the apical ones sometimes forming a sort of club. The number of segments is generally different in the males and females.

The eyes are of two kinds. Large compound eyes, one on each side of the head ; and ocelli, or so-called simple eyes. The compound eyes consist of many facets. The number differs greatly in different species, and in the different sexes, the males generally having the greatest number. Thus, in Formica pratensis there are, according to Forel, in the males about 1,200 in each eye, in the fertile females between 800 and 900, in the workers about 600. Where the workers vary in size

1 Having reference to the facts stated on page 37, this is a result of great physiological interest.

THE HEAD.

they differ also in the number of facets. Thus, again following the same authority, the large workers of Camponotus ligniperdus have 500, the smaller ones only 450; while in the Harvesting ant ( Atta barbara) the contrast is even greater, the large specimens having 230, the small ones only from 80 to 90. The ordinary workers have in Polyergus rufescens about 400 ; in Lasius fuliginosus, 200,; in Tapinoma erraticum, 100; in Plagiolepis pygmcea, 70 to 80; in Lasius jlavus, about 80 ; in Bothriomyrmex meridionalis , 55 ; in Strongylognathus testaceus, Stenamma Westwoodii, and Tetramorium ccespitum, about 45 ; in Pheulole pcdl/idula, about 30 ; Myrmecina Latreillei, 15 ; Solenopsis fugax, 6 to 9 ; while in Ponera contracta there are only from 1 to 5 ; in Eciton only 1 ; and in TypMopone the eyes are altogether wanting.