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AN

INTRODUCTION

TO

ENTOMOLOGY:

on

ELEMENTS

OF THE

NATURAL HISTORY OF INSECTS

WITH PLATES.

By WILLIAM KIRBY, M.A. F.R. and L.S.

RECTOR OF BARIIAM, AND

WILLIAM SPENCE, Esq. F.L.S.

THIRD EDITION. VOL. II.

LONDON:

I'ltlNTED run LONGMAN, HURST, REES, ORME, AND BROWN, PATERNOSTER ROW.

1823.

PRINTED BY RICHAIll) TAYLOR, SHOE LANE, I.ONnON.

CONTENTS OF VOL. II.

Letter

XVI. Societies of Insects. Page

1. Imperfect Societies, 1 25

XVII. Societies of Insects continued.

2. Perfect Societies.

JVIiile Ants. Ants, 26—106

XV'III. Perfect Societies of Insects continued.

Wasps. Himhle-heeSj 107—120

XIX. Perfect Societies of Insects continued.

Hivebee, 121—170

XX. Perfect Societies of Insects concluded.

Hivcbee, 171—217

XXI. Means by which Insects defend themselves, 218 269 XXII. Motions of Insects.

Larva and Papa, 270 303

XXIII. INIotions of Insects continued.

Lnago, 304~ 374<

XXIV. Noises produced by Insects 375 408

XXV. Luminous Insects 409—429

XXVI. Hybernation and Torpidity of Insects ,. 430 465

XXVII. Instinct of Insects 466—529

AN

INTRODUCTION

TO

E N T O JM O L O G Y.

LETTER XVI.

SOCIETIES OF INSECTS.

IMPERFECT SOCIETIES.

1 SEE already, and I see it with pleasure, that you will not content yourself with being a mere collector of in- sects. To possess a cabinet well stored, and to know by what name each described individual which it contains should be distinguished, will not satisfy the love that is already grown strong in you for my favourite pursuit ; and you now anticipate with a laudable eagerness, the discoveries that you may make, respecting the history and economy of this most interesting department of the works of our Creator. I hail wuth joy this intention to emulate the bright example, and to tread in the hallowed steps of Swammerdam, Leeuwenhoek, Redi, Malpighi, Vallisnieri, Ray, Lister, Reaumur, De Geer, I^yonct, Bonnet, the Hubers, &c.; and I am confident that

vol.. II. B

2 IMPKRFECT SOCIETIES OF IXSECTS.

a man of your abilities, discernment, and observation will contribute, in no small degree, to the treasures al- ready poured into the general fund by these yoin- illus- trious predecessors.

I feel not a little flattered when you inform me tliat the details contained in my late letters relative to this subject, have stimulated you to this noble resolution. Assure yourself, I shall think no labour lost, that has been the means of winning over to the science I love, the exertions of a mind like yours.

But if the facts already related, however extraordi- nary, have had pov/er to produce such an effect upon you, what will be the momentum, when I lay before you more at large, as I next purpose, the most striking par- ticulars of the proceedings of insects in society, and show the almost incredibly wonderful results of the combined instincts and labours of these minute beings ? In com- parison with these, all that is the fruit of solitary efforts, though some of them sufficiently marvellous, appear tri- fling and insignificant : as the works of man himselfl when they are the produce of the industry and genius of only one, or a few individuals, though they might be re- garded with admiration by a being who had seen no- thing similar before, yet when contrasted with those to which the union of these qualities in lai'ge bodies has given birth, sink into nothing, and seem unworthy of attention. Who would think a hut extraordinary by the side of a stately palace, or a small village when in the vicinity of a populous and magnificent city ?

Insects in society may be viewed under several lights, and their associations are for various purposes and of difTei'ent jdurations.

IMPERFECT SOCIETIES OF INSECTS. 3

There are societies the object of wliicli is mutual de- fence ; while that of others is the propagation of the species. Some form marauding parties, and associate for prey and plunder ; others meet, as it should seem, imder certain circumstances, merely for the sake of com- pany ; again, others are brought together by accidental causes, and disperse when these cease to operate ; and finally, others, which may be said to form proper socie- ties, are associated for tlie nurture of theii' young, and, by the union of their labours and instincts, for mutual society, help, and comfort, in erecting or repairing their common habitation, in collecting provisions, and in de- fending their fortress when attacked.

With respect to the duratioji of the societies of insects, some last only during their first or larva state ; and are occasionally even restricted to its earliest period ; some again only associate in their perfect or imago state ; while with others, the py'ojJer societies for instance, the asso- ciation is for life. But if I divide societies of insects mto perfect and imperfect, it will, I think, enable me to give you a clearer and better view of the subject. By jperfect societies I mean those that are associated in all their states, live in a common habitation, and unite their la- bours to promote a common object ; and by imperfect societies, those that are either associated during part of their existence only, or else do not dwell in a common habitation, nor unite their labours to promote a common object. In the present letter I shall confine myself to giving you some ^cco\a\\. oi imperfect societies.

Imperfect societies may be considered as of five de- scriptions : associations for the sake of company only

B 2

4 IMPERFECT .SOCIETIES OF INSECTS.

associations of males dining the season for pairing associations formed for the purpose of traveUing or emi- grating together associations for feeding together and associations that undertake some common work.

The first of these associations consists chiefly of insects in their perfect state. The httle beetles called whirlwigs {GT/ri?i7is, L.)y which may be seen clustering in groups under warm banks in every river and every pool, and wheeling round and round with great velocity ; at your approach dispersing and diving under water, but as soon as you retire resuming their accustomed movements, seem to be mider the influence of the social principle, and to form their assemblies for no other purpose but to enjoy together, in tlie sunbeam, the mazy dance. Impelled by the same feeling, in the very depth of win- ter, even when the earth is covered with snow, the tribes. of Tipulidce (usually, but improperly, called gnats) as- semble in sheltered situations at midday, when the sun shines, and form themselves into choirs, that alternately rise and fall with rapid evolutions^. To see these little aery beings apparently so full of joy and life, and feeling the entire force of the social principle in that dreary sea- son, M^hen the whole animal creation appears to suffer, and the rest of the insect tribes are torpid, always con- veys to my mind the most agreeable sensations. These little creatures may always be seen at all seasons amu- sing themselves with these choral dances ; which Mr. Wordsworth, in a late poem^, has alluded to in the fol- lowmg beautiful lines :

See also Markwick in White's Nat. Hut, ii. 256^

^ The Excursion.

iMri'.inECT sociKTits or inmxts. 5

** Nor wanting here to entertiiin tlu* tliought. Creatures that in coiiinuinitics exist, Less, as might seen), for general guardianship Or through ilcpenihmce upon mutual aid, Than by participation of tielight. And a striet love of fellowship combined. Wiiat other spirit can it be that prompts TIic gilded summer Hies to mix and weave Their sports together in the solar beam, Or in the gloom and twiliglit hum their joy?"

Another association is that of males during the season of pairing. Of this nature seems to be that of the cock- chafer and fernchafer [Mcloloniha vulgaris and solstiti- alis, F.), vhich, at certain {periods of the year and houis of the day, hover over the summits of the trees and hedges Uke swarms of bees, affording, when they ahght on the groimd, a grateful food to cats, pigs, and poultr3\ The males of another root-devouring beetle [Hoplia «;- gentea^ F.) assemble by myriads before noon in the mer- dows, when in these infinite hosts you will not find even one female ^. After noon the congregation is dissolved, and not a siufjle individual is to be seen in the air"*: while those of Mclolontha xndgaris and sohtitialis are on the wing only in the evening.

At the same time of the day some of the short-lived E})hemera3 assemble in numerous troops, and keep rising and falling alternately in the air, so as to exhibit a very amusing scene. Many of these also are males. They continue this dance from about an hour before sun-set, till the dew becomes too heavy or too cold for them. In the beginnuig of September, for two successive j'ears,

The females (SraraSceits argenlctts. Marsh.) have red legs, and the males (Scfirabccnx pitlrenilrntus, Mar->h.) black. '■ Kirh\ in Linn. Trans, v. ~.j6.

6 IMPERFECT SOCIETIES OF INSECTS.

I was SO fortunate as to witness a spectacle of this kind, which afforded me a more sublime gratification than any work or exhibition of art has power to communicate. The first was in 1811 : taking an evening walk near my house, when the sun declining fast towards the hori- zon shone forth without a cloud, the whole atmosphere over and near the stream swarmed with infinite myriads of Ephemerae and little gnats of tlie genus Chirono- mus, Latr., which in the sun-beam appeared as nume- rous and more lucid than the drops of rain, as if the heavens were showering down brilliant gems. After- wards, in the following year, one Sunday, a little before sun-set, I was enjoying a stroll with a friend at a greater distance from the river, when in a field by the road-side the same pleasing scene was renewed, but in a style of still greater magnificence ; for, from some cause in the atmosphere, the insects at a distance looked much larger than they really were. The choral dances consisted prin- cipally of Ephemerae, but there were also some of Chi- ronomi ; the former, however, being most conspicuous, attracted our chief attention alternately rising and fall- ing, in the full beam they appeared so transparent and glorious, that they scarcely resembled any thing mate- rial— they reminded us of angels and glorified spirits drinking life and joy in the effulgence of the Divine fa- vour^. The bard of Twickenham, from the terms in which his beautiful description of his sylphs is conceived in The Rape of the Lock, seems to have witnessed the pleasing scene here described ;

» The authors of this work were the witnesses of the magnificent scene here described. It was on the second of September. The first was on the ninth of that montli.

I.MI'KKl liCT SOCIETIES OF INSECTS. 7

" Sonic to the sun their insect wings uni'uUI, Waft on the hree/.c, or sink in clouds of gold j 'JVansparcnt forms, too fine for mortal sight, Their fluid boilics half dissolv'd in light ; Loose to the wind their airy garments flew, Thin glitterring textures of the filmy dew, Dipt in the richest tincture of the skies. Where liglu disports in ever mingling dyes. While every beam new transient colours flings, Colours that change whene'er they wave their wings."

1 wish yoii may have the good fortune next year to be a spectator of this all but celestial dance. In the mean time, in May and June, tlieir season of love, you may often receive nuich gratification from observing the mo- tions of a countless host of little black flies of the genus £/nj)is, {E. maura, F.) which at this period of the year assemble to wheel in aery circles over stagnant waters, with a rush resembling that of a hasty shower driven by the wind.

The next description of insect associations is of those that congregate for the purpose of travelling or emi- grating together. De Geer has given an account of the larva? of certain gnats {Tijjulce, L.) which assemble in considerable numbers for this purpose, so as to form a band of a finger's breadth, and of from one to two yards in length. And, what is remarkable, while upon their march, which is very slow, they adhere to each other by a kind of glutinous secretion ; but when disturbed they separate without difiiculty*. Kuhn mentions another of the Tipulidcc (from the antennae in his figure, which is very indifferent, it should seem a species of agaric-gnat [Mycctophila), the larva- of which live in society and

•" Dc Geer, \i. 338.

8 IMPERFECT SOCIETIES OF INSECTS.

emigrate in files, like the caterpillar of the procession- moth. First goes one, next follow two, then three, &c., so as to exhibit a serpentine ajipearance, probably fi'oni their simultaneous undulating motion and the continuity of the files ; whence the common people in Germany call them (or rather the file when on march) heerisciirmy and view them with great dread, regarding them as ominous of war. These larvae are apodes, white, sub- transparent, with black heads'. But of insect emigrants none are more celebrated than tlie locusts, which, when arrived at their perfect state, assemble as before related, in such numbers, as in their flight to intercept the sun- beams, and to darken whole countries; passing from one region to another, and laying waste kingdom after kingdom : but upon these I have already said much, and shall have occasion again to enlarge. The same tendency to shift their quarters has been observed in our little indigenous devourers, the Aphides. Mr. White tells us, that about three o'clock in the afternoon of the first of August 1785, the people of the village of Selborne were surprised by a shower of Aphides or smother-flies, which fell in those parts. Those that walked in the street at that juncture found themselves covered with these insects, which settled also upon the hedges and in the gardens, blackening all the vegetables where they alighted. His annuals were discoloured by them, and the stalks of a bed of onions quite coated over for six days after. These armies, he observes, were then, no doubt, in a state of emigration, and shifting their quar- ters ; and might have come from the great hop-planta- lions of Kent or Sussex, the wind being all that day in " Nafnrforsch. x\ ii. 1'2Q.

IMPERFECT SOCIETIES OK INSECTS. 9

the east. They were observed at the same time in njreat clouds about Faruhuni, and all along the vale from l''arn- ham to Alton". A similar emigration of these flies I once witnessed, to my great annoyance, when travelling hiter i\\ the year, in the Isle of Ely. The air was so full of them, tliat they were incessantly flying into my eyes, nostrils, &c. ; and my clothes were covered by them. And in 1814, in the autunm, the Aphides were so abundant for a few days in the vicinity of Ipswich, as to be noticed with surprise by the most incurious observers.

As the locust-eating thrush [Tardus gii/llivorus, L.) accompanies the locusts, so the Coccihellae seem to pur- sue the A})hides; for I know no other reason to assign for the vast number that are sometimes, especially in the autumn, to be met with on the sea-coast or the banks of large rivers. Many years ago, those of the Ilumber were so thickly strewed with tlie common Lady-bird (C septempwictata^ L.), that it was difficult to avoid treading upon thejn. Some years afterwards I noticed a mixture of species, collected in vast numbers, on the sand-hills on the sea-shore, at the north-west extremity of Norfolk. ]My friend tlie Rev. Peter Lathbury made long since a similar observation at Orford, on the Suffolk coast ; and about five or six years ago they covered the cliffs, as I have before remarked'-, of all the watering- places on the Kentish and Sussex coasts, to the no sn)all alarm of the suj)orstitious, who thought them forerunners of some direful evil. These last probably emigrated with the Aphides iVom llie hop-grounds. Whether the latter and their dcvourers cross the sea has not been ascer- ' Xal. f/ist. ii. 101. '- Vol.. J. Itii Va]. :g:\

10 IMPERFECT SOCIETIES OF INSECTS.

tained; that the Coccinellae attempt it, is evident from theii* alighting upon ships at sea, as I have witnessed mysel£ This appears clearly to have been the case with another emigi'ating insect, the saw-fly {Tenthredo) of the turnip (which, though so mischievous, appears never to have been described ; it is nearly related to T. Centifolice^ Panz.)'. It is the general opinion in Norfolk, Mr. Marshall in- forms us^, that these insects come from over sea. A farmer declared he saw them anive in clouds so as to darken the air ; the fishermen asserted that they had re- peatedly seen flights of them pass over their heads when they were at a distance from land ; and on the beach and cliffs they were in such (juantities, that they might have been taken up by shovels-full. Three miles in-land they were described as resembling swarms of bees. This was in August 1782. Unentomological observers, such ' as farmers and fishermen, might easily mistake one kind of insect for another ; but supposing them correct, the swarms in question might perhaps have passed from Lincolnshire to Norfolk. Meinecken tells us, that he once saw in a village in Anhalt, on a clear day, about four in the afternoon, such a cloud of dragon-flies {Li- hellulcB^ L.) as almost concealed the sun, and not a little alarmed the villagers, under the idea that they were lo- custs '^ ; several instances are given by Rbsel of similar clouds of these bisects having been seen in Silesia and other districts '^ ; and Mr. Woolnough of Hollesley in Suffolk, a most attentive obser\er of nature, once wit- nessed such an army of the smaller dragon-flies [Agrion^ F.) flying in-land from the sea, as to cast a slight shadow

« Fn. Genu. Iiiif. xHx. 18. •' P/dhs. rraiis. Ixxiii. 'Jl/.

y Xalurfursch, vi. 110. „• " li. 1.35.

IMPERFECT SOCIETIES OF INSECTS. 11

over a field of ibur acres as they passed. Professor Walch states, that one night about eleven o'clock, sitting in his stiuly, his attention was attracted by what seemed the pelting of hail against his window, which surprising him by its long continuance, he opened the window, and found the noise was occasioned by a flight of the fi'oth frog-hopper [Cicada spumaria, L.), which entered the room in such numbers as to cover the table. From this clrciunstance and the continuance of the pelting, which lasted at least half an hour, an idea may be formed of the vast host of this insect passing over. It passed from east to west ; and as his window faced the south, they only glanced against it obliquely^. He afterwards wit- nessed, in Ausfust, a similar emijjration of myriads of a kind of beetle [Carabiis vulgaris^ L.)**. Another writer in the same work, H. Kapp, observed on a calm sunny day a prodigious flight of the noxious cabbage-butterfly {Papilio Brassictc, L.), which passed from north-east to south-west, and lasted two hours *^. Kalm saw these last insects midway in the British Channel'^. Lindley, a writer in the Royal Military Chronicle, tells us, that in Brazil, in the beginning of March 1803, for many days successively there was an immense flight of white and yellow buttei-flies, probably of the same tribe as the cal> bage buttei-fly. They were observed never to settle, but proceeded in a direction fiom north-west to south-east. No buildings seemed to stop them from steadily pursuing their course ; which being to the ocean, at only a small distance, they must consequently perish. It is remarked that at this time no other kind of buttei-fly is to be seen,

» Xaltiiforsc/i. \ i. 111. '' ll)i(l. xi. 95.

'^^ Ibid. 9-1. <* Tiavc(s,\. 13.

12 IMPERFECT SOCIETIES OF INSECTS.

though the country usually abounds in such a variety*. Major Moor, while stationed at Bombay, as he was playing at chess one evening with a friend in Old Wo- man's Island, near that place, witnessed an immense flight of bugs [Chnices), which were going westward. They were so numerous as to cover every thing in the apartment in which he was sitting. When staying at Aldeburgh, on the eastern coast, I have, at certain times, seen innumerable insects upon the beach close to the waves, and apparently washed up by them. Though wetted, they were quite alive. It is remarkable, that of the emigrating insects here enumerated, the majority for mstance the Libellula?, Coccinellae, Carabi, Cicadae, gtc. are not usually social uisects, but seem to congre- gate, like swallows, merely for the purpose of emigration. What incites them to this is one of those mysteries of nature, which at present we cannot penetrate. A scarcity of food urges the locusts to shift their quarters ; and too confined a space to accommodate their numbers occa- sions the bees to swarm : but neither of these motives can operate in causing unsocial insects to congregate. It is still more difficult to account for the impulse that lu'ges these creatures, with their filmy wings and fi*agile form, to attempt to cross the ocean, and expose them- selves, one would think, to inevitable destruction. Yet, though Ave are unable to assign the cause of this singular instinct, some of the reasons which induced the Creator to endow them with it may be conjectured. This is clearlv one of tlie modes by which their numbers are kept within due limits, as, doubtless, the great majority of these adventurers perish in the waters. Thus, also, a * n. Mihl. Clinm. tl.r March 181,1, p. 4u'3.

IMPKHllU')' SOCIETJKS Ol INSECTS, 13

gro.it suiiply of food is furnished to those fisli in the sea itself, which at other seasojis ascend the rivers in search of thcni ; and this probably is one of the means, if not the only one, to which the numerous islands of this f^lobe are indebted for their insect population. Whether the insects I observed upon the beach wetted by the waves, had flown from our own shores, and falling into the water had been brought back by the tide; or whether they had succeeded in the attempt to pass from the continent to us, by flying as far as they could, and then falling had been brought by the waves, cannot certainly be ascertained ; but Kalm's observation inclines me to the latter opinion.

The next order of imperfect associations is that of tliose insects which feed together: these are of two de- scriptions— those that associate in their Jirst or last state only, and those that associate in all their states. The first of these associations is often very short-lived : a patch of eggs is glued to a leaf; when hatched, the little larvae feed side by side very amicably, and a pleasant sight it is to see the regularity with which this work is often done, as if by word of command; but when the leaf that served for their cradle is consumed, their society is dissolved, and each goes where he can to seek his own fortune, re- gardless of the fate or lot of his brethren. Of this kind are the larvae of the saw-fly of the gooseberry, whose ra- vages I have recorded before*, and that of the cabbage- butterfly ; the latter, however, keep longer together, and seldom wholly separate. In their final state, I have no- ticed that the individuals of T/irips Phj/sapus, the fly that causes us in hot weather such intolerable titillation, are very fond of each other's company when tliey feed. To- » Vol.. I. 4fh EtI. 1.05.

14 IMPERFECT SOCIETIES OF INSECTS.

wards the latter end of last July, walking through a wheat- field, I observed that all the blossoms of Convolvulus arvensis, though very numerous, were interiorly turned quite black by the infinite number of these insects, which were coursinsr about within them.

But the most interestino; insects of this order are those which associate in all their states. Two populous tribes, the great devastators of the vegetable world, the one in warm and the other in cold climates, to which 1 have al- ready alluded mider the head of emigrations you per- ceive I am speaking of Aphides and Locusts are the best examples of this order : although, concerning the societies of the first, at present we can only say that they are merely the result of a common origin and station : but those of the latter, the locusts, wear more the appearance of de- sign, and of being produced by the social principle.

So much as the world has suffered from these animals *, it is extraordinary that so few observations have been made upon their history, economy, and mode of proceed- ino-. One of the best accounts seems to be that of Pro- fessor Pallas, in his Travels into the Southern Provinces of the Russian Empire. The species to which his prin- cipal attention was paid appears to have been the Grryllus italicus^ in its larva and pupa states. " In serene warm weather," says he, " the locusts are in full motion in the morning immediately after the evaporation of the dew ; and if no dew has fallen, they appear as soon as the sun imparts his genial warmth. At first some are seen run- ning about like messengers among the reposing swarms, which are lying partly compressed upon the ground, at the side of small eminences, and partly attached to tall ' See Vol.. 1. 4tii Ed. 212.

IMPERFECT SOCIETIES OF IXSE.CTS. 15

plants and shrubs. Shortly after the whole body begins to move forward in one direction and with little deviation. They resemble a sAvarm of ants, all takin<r the same coarse, at small distances, but without touchiufr each other : they uniformly travel towards a certain region as fast as a fly can run, and without leaping, unless pursued ; in which case, indeed, they disperse, but soon collect again and follow their former route. In this maimer they advance from morning to evening without halting, frecjuently at the rate of a hundred fathoms and upwards in the course of a day. Although they prefer marching along high roads, ftxjtpaths, or open tracts; 3'et when their progress is o})posed by bushes, hedges, and ditches, they penetrate through them : their way can only be im- peded by the waters of brooks or canals, as they are ap- parently terrified at every kind of moisture. Often, how- ever, they endeavour to gain the ojiposite bank with the aid of overhanging boughs; and if the stalks of plants or shrubs be laid across tlie water, they pass in close columns over these temporary bridges ; on which they even seem to rest and enjoy the refreshing coolness. Towards sun- set the whole swarm gradually collect in parties, and creep up the plants, or encamp on slight emmences. On cold, cloudy, or rainy days they do not travel. As soon as they acquire wings they progressively disperse, but still fly about in large swarms ^. "

*' In the month of May, when the ovaries of these in- sects were ripe and turgid," says Dr. Shaw^, "each of these swarms began gradually to disappear, and re- tired into the Mettijiah, and other adjacent plains, where » Pallas, ii. 422-(>. '- Travels, \S7.

16 IMPERrF.CT SOf'IETlES OF INSECTS.

they deposited their eggs. These wore no sooner hatched in June, than each of the i)roods collected it- self into a compact body, of a furlong or more in square; and marching afterwards directly forwards toward the

sea, they let nothing escape them tlicj/ kept iheir

ranks^ like men of 'nccn- ,- climbing over, as they ad- vanced, every tree or wall that was in their way; nay, they entered into our very houses and bed-chambers,

like 50 many thieves. A day or two after one of these

hordes was in motion, others were already hatched to

march and glean after them. Having lived near a

month in this manner they arrived at their full

groAvth, and threw off their mjmpha-state by casting their outward skin. To prepare themselves ft)r this change, they clung by their hinder feet to some bush, twig, or corner of a stone ; and immediately, by using an undu- latinir motion, their heads would first break out, and then the rest of their bodies. The whole transformation was performed in seven or eight minutes ; after which they lay for a small time in a torpid and seemingly in a lanauishing condition ; but as soon as the sun and the air had hardened their wings, by drying up the moisture that remained upon them after casting their sloughs, they reassumed their former voracity, with an addition of strength and agility. Yet they continued not long in this state before they were entirely dispersed." The species Dr. Shaw here speaks of is probably not the Gryllus migraforius, L.

The old Arabian fable, that they are directed in their flights by a leader or king % has been adopted : but I 3 Bochart, Hierozoic. ii. 1. 4. c. 3. 460.

IMPERFECT SOCIKTIES OF INSECTS. 17

think without sufficient reason, by several travellers. Thus Benjamin BuUivant, in his observations on the Natural History ot" New England *, says that " the lo- custs have a kind of reginiental discipline, and as it were some commanders, which show greater luid more splen- did wings than the common ones, and arise first when pursued by the fowls or the feet of the traveller, as I have often seriously remarked." And in like terms Jackson observes, that " they have a government amongst them- selves similar to that of the bees and ants ; and when the [Sultan Jcrraad) king of the locusts rises, the whole body follow him, not one solitary straggler being left behind ^." But that locusts have leaders, like the bees or ants, di- stinguished from the rest by the size and splendour of their wings, is a circumstance that has not yet been esta- blished by any satisfactory evidence ; indeed, very strong reasons may be urged against it. The nations of bees and ants, it must be observed, are housed together in one nest or hive, the whole population of which is ori- ginally derived fi-om one common mother, and the leaders of the swarms in each are the females. But the armies of locusts, though they herd together, travel together, and feed together, consist of an mfinity of separate families, all derived from different mothers, who have laid their eggs in separate cells or houses in the earth ; so that there is little or no analogy between the societies of locusts and those of bees and ants ; and this pretended sultan is some- thing quite different fi-om the queen-bee or the female ants. It follows, therefore, that as the locusts have no common mother, like the bees, to lead their swarms, there

* In Philos. Trans, (or 1698. '' Jackson's Morocco, 51.

VOL. II. C

18 IMPERFECT SOCIETIES OF INSECTS.

is no one that nature, by a different organization and ainjjler dimensions, and a more august fonn, has destined to this high office. The only question remaining is, whe- ther one be elected from the rest by common consent as their leader, or whether their instinct impels them to fol- low the first tliat takes flight or alights. This last is the learned Bochart's opinion, and seems much the most rea- sonable*. The absurdity of the other supposition, that an election is made, M'ill appear from such queries as these, at which you may smile Who are the electors ? Are the myriads of millions all consulted, or is the elec- tive franchise confined to a few ? Who holds the courts and takes the votes ? Who casts them up and declares the result? When is the election made? The larvae appear to be as much under government as the perfect insect. Is the monarch then chosen by his peers when they first leave the egg and emerge from their subter- ranean caver-ns ? or have larva, pupa, and imago each their sejiarate king ? The account given us in Scripture is certainly much the most probable, that the locusts have no king, though they observe as much order and regu- larity in their movements as if they were under mili- tary discipline, and had a ruler over them''. Some spe- cies of ants, as we learn from the admirable history of them by M. P. Huber, though they go forth by common consent upon their military expeditions, yet the order of their cx>lurnns keeps perpetually changing; so that those who lead the van at the first setting out, soon fall into llie retir, and others take their place : their successors do the same: and such is the constant order of their march.

_, * Hoohart, Hiernzoiv. iibi supra. '' Proverbs xxx. 37.

IMPEKFF.CT SOCIETIKS OF INSECTS. 19

It seems probable, as these eolinnns nie exteiuled to a con- siderable length, that tin- object of this successive chann-e oi'leaders is to convey constant intelligence to those in the rear, of what is going forward in the van. M'hether any thing like this takes place for the regulation of their motions in the innumerable locust-armies, which aie sometimes co-extensive with vast kingdoms ; or whether iJieir instinct simply directs them to follow the first that moves or flies, and to keep their measured distance, so tliat, as the prophet speaks, "one does not thrust another, and they walk every one in his path^, " must be left to future naturalists to ascertain. And I think that you will join with me in the wish that travellers, who have a taste for Natural History, and some knowledge of insects, would devote a share of attention to the proceedings of these celebrated aninuils, so that we might have facts in- stead of fables.

The last order of imperfect associations approaches nearer to perfect societies, and is that of those insects which the social princi}ile urges to imite in some common work for the benefit of the community.

Amongst the Coleoptcra, Atcuckits pilularius, F., a bee- tle before mentioned, acts under the influence of this prin- ciple. "I have attentively admired their industry and mutual assisting of each other," says Catesby, " in roll- ing those globular balls tVom the place where they made them, to that of their interment, which is usually the di- stance of some yards, more or less. This they perform breech foremost, by raising their hind parts, forcing alonjr the ball with their hind feet. Tv.o or three of

» Joel ii. 8. C 2

20 IMPERFfiCT SOCIETIES OF INSECTS.

them are sometimes engaged in trundling one ball, which, from meeting with impediments from the unevenness of the ground, is sometimes deserted by them : it is how- ever attempted by others with success, unless it happens to roll into some deep hollow chink, where they are con- strained to leave it ; but they continue their work by roll- ing off' the next ball that comes in their way. None of them seem to know their own balls, but an equal care for the whole appears to affect all the community ^. "

Many larvae also of Lejndoptera associate with tliis view, some of which are social only during part of their existence, and others during the whole of it. The first of these continue together while their united labours are beneficial to them ; but when they reach a certain period of their life, they disperse and become solitary. Of this kind are the caterpillars of a little butterfly [Papilio Cinxia) which devour the narrow-leaved plantain. The families of these, usually amounting to about a hundred, miite to form a pyramidal silken tent, containing several apartments, which is pitched over some of the plants that constitute their food, and shelters them both from the sun and the rain. When they have consumed the provision which it covers, they construct a new one over other roots of this plant ; and sometimes four or five of these encamp- ments may be seen within a foot or two of each other. Against winter they weave and erect a stronger habitation of a rounder form, not divided by any partitions, in which they lie heaped one upon another, each being rolled up. About April they separate, and continue solitary till they assume the pupa.

Catesbv's Carolina, ii. 111. See above. Vol. I. 4th Ed. 349.

IMPERFECT SOCIETIES OF INSECTS. 21

Reaumur, to whom I am iudebted for this account, has also given us an interesting history of another in- sect, the gokl-tail-moth before mentioned, whose cater- pillars are of this description. Tliey belong to that family of Bombyces, which envelop tiieir eggs in hair plucked from their own body. As soon as one of these young caterpillars is disclosed from the egg, it begins to feed ; another quickly joins it, placuig itself by its side ; thus they proceed in succession till a file is formed across the leaf: a second is then begiin ; and after this is completed, a third and so they proceed till the whole upper surface of the leaf is covered : but as a single leaf will not contain the whole family, the remainder take their station upon the adjoining ones. No sooner have they satisfied the cravings of hunger, than they be- gin to think of erecting a common habitation, which at first is only a vaulted web, that covers the leaf they in- habit, but by their united labours in due time grows into a magnificent tent of silk, containing various apart- ments sufficient to defend and shelter them all from the attack of enemies and the inclemency of the seasons. As our caterpillars, like eastern monarchs, are too deli- cate to adventure their feet upon the rough bark of the tree upon which they feed, they lay a silken carpet over every road and pathway leading to their palace, which extends as far as they have occasion" to go for food. To the habitation just described they retreat during heaA^ rains, and \Vhen the sun is too hot: they 'likewise pass part of the night in them ; and, indeed, at all times some may usually be found at home. Upon any sudden alarm they retreat to them for safety, and also when they cast their skins : in the winter they are wholly confined

22 I.AIPEIU'ECT SOCIETIES OE INSECTS.

to them, emerging again in the spring : but in May and June they entirely desert them; and, losing all their love for society, live in solitude till they become pupae, which takes place in about a month. When they desert their nests, the spiders take possession of them ; which has given rise to a prevalent though most absurd opinion, that they are the parents of these caterpillars*.

With other caterpillars the association continues during the whole of the larva state. De Geer mentions one of the Tefithredinidce of this description which forn^ a common nidus by connecting leaves together witl silken threads, each larva moreover spinning a tube o the same material for its own private apartment, in whicl it glides backwards and forwards upon its back^. I have observed similar nidi in this country; the insects that form them belong to the Fabrician genus Lyda.

The most remarkable insects, however, that arrange under this class of imperfect associates, are those that observe a particular order of march. Though they move without beat of drum, they maintain as much regularity in their step as a file of soldiers. It is a most agreeable sight, says one of Nature's most favoured admirers. Bonnet, to see several hundreds of the larvae of P. B. Neustria marching after each other, some in straight lines, others in curves of various inflection, re- sembling, from their fiery colour, a moving cord of gold stretched upon a silken ribband of the purest white; this ribband is the carpeted causeway that leads to their leafy pasture from their nest. Equally amusing is the progress of another moth, the Pityocampa^ before no-

Vol, I. 4tli Ed. 1/7. Reaumur, ii. 125. >• De Gecr,ii. 1029.

IMI'KHKlA.r SOdLTlKS OF INSKCTS. 23

ticed; they march l<)»^ttlicr IVdiu ihcir coniinon citadel, consisting of pine-leave* united and iinvovcn with ihc silk which they spin, in a single line: in lollowinjr each otiier they describe a nuiltitude of graceful curves of varying figure, thus lijrniing a series of living wreaths, which change their sluij>e every moment : all move with a uniform pace, no one pressing too forward or loitering behind ; when the first stops, all stoj), each defiling in exact military order*.

A still more singular and pleasing sj)ectacle, when their regiments march out to forage, is exhibited by the Proccssionarj/ Bombijx, This moth, which is a native of France, and has not yet been found in this country, in- habits the oak. Each family consists of from 600 to 800 individuals. When young, they have no fixed luibitation, but encamp sometimes in one place and some- times in another, under the shelter of their web : but when they have attained two-thirds of their growth, they weave for themselves a common tent, before de- scribed''. About sun-set the regiment leaves its quar- ters ; or, to make the metaplior harmonize with the trivial name of the animal, the monks their ccrnobium. At their head is a chief, by whose movements their proces- sion is regulated. When he stops, all stop, and pro- ceed when he proceeds; three or four of his immediate followers succeed in the same line, the head of the second touching the tail of the first; then comes an equal series of pairs, next of threes, and so on as far as fifteen or twenty. Tiie whole procession moves regularly on

' Bonnet, ii. o/. '' Vol. I. 1th Kd. l/H.

24 IMPERFECT SOCIETIES OF INSECTS.

with an even pace, each file treading upon the steps of those that precede it. If the leader, arriving at a par- ticular point, pursues a different direction, all march to that point before they turn. Probably in this they are guided by some scent imparted to the tracks by those that pass over them. Sometimes the order of procession