Insect behavior

Front matter

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R\UL GRISWOLD HOWG

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Preface

IN preparing this little volume my object has been to produce a work written in a light enough vein to be entertaining to the reader, however casually interested he may be in insect life, but at the same time, one that is in every way scientifically accurate.

In the chapters which follow, I have endeavored to describe as vividly as it lies within my power to do, various phases of insect behavior which I have been fortunate enough to observe and record during many years spent in active field work.

Chapters II to VIII inclusive, treat exclusively of South American insects, studied in the jungles of British Guiana, and while they are interesting species, whose habits have heretofore remained unrecorded, they possess no more wonderful life stories than our insects of the Eastern States, whose habits, for the most part, make up the remainder of this book.

Wherever one searches in the world of insects there is something new to be found. Perhaps only an unrecorded habit, or a slight problem to be solved, yet each problem leads to another, and soon one is led unconsciously into the depths of the study. Once in, there appears to be no way out, and I for one do not wish to retrace my steps to the freedom I knew before the fascination of this study laid hold of me.

If this book leads others into the world of insect study or, in some measure, brings home to the reader, the same fascination that these life stories hold for the author, then its object will be fully realized.

For the use of chapters II to VIII inclusive, which originally appeared in Volume I of Tropical Wild Life in British Guiana, I am lo PREFACE

greatly indebted to the New York Zoological Society, and to those

magazines who have published other chapters as separate articles,

and have now given their consent to their use in this book, I wish

also to acknowledge my grateful thanks.

Last but not least, to Lillian Carey Howes, upon whom has fallen

the main burden of preparing my manuscript for the printer, I make

grateful acknowledgment.

Paul Griswold Howes.

Stamford, Conn.,

January i, 1918.

Contents

CHAPTER PAGE

I The Insect World at Close Range 19

II The Black Reed-Wasp 27

II List Of Illustrations

FACING PAGE

iEschnid dragon-fly preying upon a house fly Frontisfiece

A centipede greatly enlarged 21

Grasshoppers fighting 21

Staphylinid beetle preying upon a fly 22

An assassin bug laying her eggs 24

A handful of vegetation at close range 26

A photograph made under asparagus plants 26

Plough furrows are as mountain ranges to the insects 31

A greatly enlarged hemipterous insect . 31

Male black reed-wasp guarding nesting tube 33

Female black reed-wasp arriving at the tube 33

Glass tube removed from box, showing plugs, egg and spiders .... 33

Old nest of wasp used by the black reed-wasp . 33

Stages in the larval sacrifice 35

Newly transformed pupa of the roach-killer 35

Spider used as provender by the white-footed wasp 40

Cocoon of white-footed wasp . 40

Tangle of reeds and razor grass in British Guiana 40

Two common bugs which do great damage to squash vines 49

Open nest of the forest shell-wasp 56

Open nest and larva of the forest shell-wasp 56

Newly emerged one-banded dauber 65

Suspended hatching egg of the forest shell-wasp 65

One-banded dauber working upon her nest 65

Four types of nests made by the one-banded dauber 65

Spider prey and egg of the blue huntress 68

Pupa of the blue huntress showing T-shaped jacks 68

A queen paper wasp at her nest 72

A cabbage butterfly depositing an egg folio-wing 76

14 LIST OF ILLUSTRATIONS

FACING PAGE

Cocoons of ichneumon parasite of cabbage butterfly larva 76

Male and female paper-wasps hatching in July 81

Paper-wasp worker with unusually large pellet of paper 81

The cannibal's nest layed open 85

A cannibal wasp at her nest 85

The cannibal and her diggings 86

A complete lead model of the cannibal wasp's burrow 86

A wasp of the sphecid's size compared to a rove beetle 88

Sphecid wasp dragging a paralyzed cicada to her burrow 88

Common cicada, upon which the sphecid wasp preys 88

Comparative wing expanse of cicada and sphecid wasp 90

Hole in cicada through which the young sphecid entered 90

Young sphecid wasp two days old feeding on its host 90

Queen paper wasp in the act of depositing an egg following 92

Photomicrograph of eggs of the paper wasp . following 92 .

Paper wasp cells showing young and silken cocoon-caps 95

Life size nest of paper-wasp 95

Cells of the paper-wasp with caps removed to show young 97

Paper wasp cells in section showing larva and pupa 99

Epeira insularis, an orb-building spider, laying eggs I02

A spider using a cicada's shell as a hiding place 104

An example of spider strategy 104

The fishing net of a hydropsychid and its maker ........ 106

Ants surrounding and pillaging a larger one following 108

Brown ants transporting aphids to their underground nest . . following 108

Actual debris gathered up after an ant battle following 108

Carpenter ants tending their aphid "cattle" following 108

Paralyzed and dying South American leaf-cutter ants ill

A group of dead ants all linked together lii

Carpenter ants proceeding to battle 113

A severed head of an enemy clinging to a dead ant 113

A train of South American army ants 113

Leaf-cutter ants with heads and abdomens eaten away 113

Young brown ants carefully tended by their nurses 115

Young brown ants brought up beneath a sun-warmed stone 115

LIST OF ILLUSTRATIONS 15

FACING PAGE

A snowy tree cricket singing ii8

The typical dragon-fly face 120

A robber-fly with its prey 120

Photomicrograph through the eye windows of a fly . . . . . . . . 122

A harvestman following 124

Egg mass of the greenbottle fly following 124

A greenbottle laying eggs upon the head of a dead bird 127

Greenbottle laying eggs in the bill of a starling 1 27

Young greenbottle flies at work 129

Skeleton of a muskrat cleaned by young greenbottle flies . 131

Test tubes containing foods liquefied by young flies 131

Nest of the mound-building ants 134

Cecropia caterpillars twenty-five days old 138

Cecropia caterpillar casting its skin 138

Caterpillars of the cecropia just after the second cast 138

Eggs of the cecropia on an apple leaf 138

Female cecropia moth 143

The full grown cecropia caterpillar 143

Newly completed cocoon of the cecropia caterpillar 143

Squash flower opened to show nectar cup 147

How the honey bee reaches the nectar in a squash flower 147

A beetle at the entrance of the nectar cup 147

Fertilized blossoms of the squash plant 148

The yellow gaping throat of a squash flower 148

Foamy dwellings of immature spittle bugs 150

Growth of the spittle mass 150

A dried spittle mass and the mature insect 152

Huge spittle mass found in the jungle of British Guiana 152

A thread-legged bug laying eggs 154

A stampede of thread-legged bugs 156

Greatly enlarged head of the thread-legged bug following 156

A characteristic attitude of the thread-legged bug following 156

A thread-legged bug casting its skin 157

Spring-tails in their tiny world 159

Spring-tails showing spines upon their bodies 159 i6 LIST OF ILLUSTRATIONS

FACING PAGE

A tiny solitary bee resting between journeys i6i

Making a plaster cast of the bee's burrow i6i

Entrance to the bee's tunnel showing surroundings i6i

Model of the bee's nest made from a plaster cast 163

Interior of the bee's burrow showing cell and food 163

Excavating the cast of the burrow 163

Caterpillar of a geometrid moth which resembles a twig . . . following 164

Caterpillar which mimics the excretia of a bird following 164

Chrysalis of the mourning cloak butterfly 168

Cochlidiid caterpillar which mimics a leaf-bud 168

Thread-legged bug in its original environment following 170

Poison spines of the lo caterpillar following 170

Wood lice or pill bugs 173

A thysanuran or bristle-tail 173

Chapter I The Insect World At Close Range

NOT SO long ago my world was commonplace; even dull at times. Tranquil and uninteresting, until one day a tiny voice broke the silence of my study. It led me from my dusty chimney corner, dropped me suddenly into the new and fevered world of insects, and there it left me.

Who can tell how long this new world had lain before me unnoticed, a world of tiny people within our own big world, fighting out their destinies beneath our very feet? I found it a land of marvels and excitement, where great geographical upheavals are but momentary matters; where changes, rivaling those wrought by a million years in our environment, occur from day to day, a land where there is no uniformity of change. I found disorder and repose walking hand in hand, neither more of one than the other, yet much of both. I stopped; marveled, became fascinated, with this land so new and mysterious, into which I could step without effort, from my study door.

There were jungles, immense ones, rank and tangled, grown with gigantic trees whose bark was an armor of thorns. Myriad life inhabited them, and a thousand different creatures prowled about hunting one another. In the tree tops, along their swaying trunks and in the tangles below, every living thing was fighting for existence. Were our ears attuned to the vibrations of this jungle, a terrifying sound, dwarfing all others, would reach them, a grinding of life between myriad jaws, merciless, endless, for such is life in this new world.

Such an existence in such a forest is'beyond our comprehension. It is the exception to survive long here. Each species preys upon, or fights to exterminate the next. There are serpents of great length and colossal rodents that comparatively dwarf a mastodon, which add to the excitement of life. It is fortunate that the creatures peopling such a world possess little if any intelligence. Indeed it is possible that they were purposely deprived of it lest they fear to venture forth.

Now this jungle may flourish into a great wilderness, a forest whose real floor the sun never reaches. Here among the buts of the trees, weird creatures are encountered. Ugly crab-like things that suck the blood of others, minute horny creatures and indescribable crawling ones whose life story and functions nobody yet knows.

Above the dead fallen stems that cover this tomb life, a second group of living things is encountered. Larger creatures capable of utterances of a harsh nature, hard shelled beasts and triangularbodied ones that emit disgusting odors.

One night the jungle flourishes, green and rich with swaying, surging life and energy, but the next night it has vanished. Every tree has fallen by some mysterious hand; millions of creatures perish and all is confusion. What has occurred claims a greater toll than war, yet, as we shall see, it is by no means a miracle.

Beyond the vanishing jungle lies a country of another type, the like of which no human being has ever seen.

Imagine a series of parallel mountain ranges, three hundred in number, of great length, with as many narrow valleys lying between. The country is nearly barren yet strangely rich in soil. At great distances some green thing finds courage to lift its head, standing

'Minute horny creatures and indescribable crawling ones whose hfe story and functions nobody yet knows'

A centipede greatly enlarged i[ I ""Mi"

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THE INSECT WORLD AT CLOSE RANGE 21

out like a palm in an oasis, giving its mite of shelter from the sun. Lying about in no order, one sees great boulders, some rounded, others with jagged dangerous edges and many bearing white wounds as though a giant hammer had tried to cleave them.

There is a scarcity of animal life here just as there is a scarcity of vegetation, but one or two creatures revealed by the hunt are interesting.

One possesses a bony orange head that glistens like polished armor. It is armed additionally with heavy curved tusks, working sidewise with great strength, but for all this war-like apparatus its body is fat and pudgy. Such a hypocrite could be attacked from behind with safety. The creature rolls about aimlessly and one is forced to wonder how it obtains its food.

Another is a hairy eight eyed creature, possessed of as many agile legs that carry it rapidly from place to place. It lives in damp caves beneath boulders, darting out upon the unwary. In the seclusion of its cave it sucks its victim's blood casting out the skeleton as a warning to others.

We pass on. The journey brings us through another jungle of immense fruit trees bearing large objects resembling cocoanuts and thence to a lake of great extent, backed up by a group of mountains. Over the water one sees large flying creatures, with tremendous eyes and slender, plated bodies. They hover over the expanse below, occasionally swooping down upon creatures of lesser bulk, whom they consume greedily.

In front of us there are slimy flats sloping toward the lake. Pufis of tainted air lead to the discovery of a mass of carrion near the water's edge. Here is something of interest.

Upon the manna a multitude of animals are gorging. Most of them are similar in body, being long, fleshy and alert. They appear to be fighting greedily for the repast upon which they are exuding a strange fluid to assist digestion. They move continually about by means of grapnels which enable the animals to progress either forward or backward by repeated contractions of their muscles.

Other animals are attracted by the odor of decay and from far and near they come to seek the cause. Some to their advantage, others to their detriment, for a cannibal lies in wait for them.

It is a powerful animal, slender and supple-bodied, with a coat of glossy bronze velvet. It is perhaps the most active of all the weird creatures that we have come to know, moving like a flash in response to stimulae. It could not exist were patience a necessity, at least one is so impressed upon observing it.

There are many tunnels twisting into the carrion, excavated by other creatures, and one of these the cannibal selects for its abode, until the flesh becomes too dry to act as lure. In this grewsome cave the creature rests, its eyes roving and its whole body ready to spring at an instant's notice, which it does upon all who venture within its range. Indeed we have found a veritable dragon in this creature so fiery and ready for battle. Its prey is helpless before the onslaught and its teeth sink easily through armor.

Leaping upon the back of its victim, the dragon tears deep into its body, grinding flesh and skeleton, sucking every drop of blood until the broken creature curls, dry like a leaf. In a few seconds the unlucky one has disappeared before our eyes. A minute ago we saw a living creature come to the carrion to stay its appetite. Next we heard a crunching noise and saw a splash of blood. Now there is nothing but the retreating cannibal and we gaze dumbfounded at the spot where the scene was enacted.

From the lake we journey on, through a wide and heavy section of woodland, on our way to the desert that lies beyond. As we go we have many weird experiences and see many curious sights, but lack of time prevents their proper observation. We must reach the

THE INSECT WORLD AT CLOSE RANGE 23

desert at once, lest we arrive too late to see the pitfalls of the desert lions.

At length the broiling sands are reached and none too soon. The lions only build their traps at certain times of the year and few signs of them are encountered. A search reveals four pits, however, placed in the neighborhood of a colony of burrowing creatures common to the desert.

The pits are deep conical excavations in the sand, so cunningly constructed as to compel admiration despite the clumsy makers, who walk backwards in preference to forward.

At this time the lions are still youthful and being grotesque and cumbersome of body, must therefore secure their prey by strategy. Each individual excavates a pitfall, cone-shaped as we have seen. At the apex of the cone, which is deep in the ground, the creature conceals itself with only the sabre-like, sand-colored mandibles protruding.

Let us watch from a safe distance the methods employed. We have not long to wait, for a constant stream of animals are pouring in and out of their burrows near by. Many keep at a safe distance; others escape more through good fortune than intelligence, but at length a stupid individual arrives at a pit and heedlessly places one foot over the edge.

At once the footing crumbles and the poor animal starts on its journey. Once, in its frantic struggles, it appears to regain the lost footing, but seeing or expecting this, the lion hurls a multitude of rocks from below, which once more start the sand sliding and the victim meets its death in merciless, waiting jaws.

Now we might travel on and on, from the desert to another valley, lying between inspiring mountain chains, thence to a dried up ocean bed, across a great river into more jungle and so on, indefinitely, witnessing an endless series of geographical and living wonders that would soon bewilder us.

We can go no further now. Our expedition into the new world must needs come to an end. Before we return home, we are, however, to witness the approach and arrival of a new period. We are to see with our own eyes and in a very short time, the temporary death of this curious land.

The period, which is a glacial one, comes rapidly and is marked by great frosts, capable of killing an entire jungle in a single night. With each successive frost, countless millions of creatures perish, the weakest dying at once, the stronger surviving for a slightly longer period. Lakes and oceans freeze solid from surface to their depths, valleys and mountains are buried with snow and in an incredibly short time, perhaps a month or two, life in this lately flourishing land through which we have traveled may be cold and dead.

A glacial period has come, transforming the land into a desolate waste. It has apparently carried all life before it.

A fertile earth today, a barren moon tomorrow, such is this new world within our own!

*******

Let us now see just what this new world is and where our travels have led us. We have barely looked into its treasure house of wonders, but for all that, we have learned something and our eyes have been opened to its possibilities.

Its geography is our own, more minutely seen, analyzed as it were into its smallest parts. To study its wonders one must lose sight of all large unimportant things. Real mountains, lakes, deserts, objects that make our geography, all must be ignored. They are too evident to be considered and to bother with them as a whole would be like hoarding something without value.

If we examine a great painting closely, we see only a melee of mean-

AnotluM' stiMiiiii- cioatun- of the insect world

I'.nlarjicd six tiniis i

THE INSECT WORLD AT CLOSE RANGE 25

ingless strokes; dabs of color placed together like the patches of a crazy quilt. So we may liken this new, or insect world, to these strokes and dabs that collectively make the painting. In a word the new world consists of the particles that, heaped together, compose the mountain, the valley and the desert of our own.

When we were coaxed from our study by the excitement of discovery, we stepped across the lawn into a field of waving hay. It was bordered with a heavy growth of weeds and other vegetation. Stopping to analyze, we found a jungle of the insect world. At the other end of the field the farmers were already swinging their scythes — thus the jungle vanished in a day.

We journeyed on to another field, so recently turned over by the plough that vegetation had only appeared at intervals. There were three hundred furrows, mountain ranges to an insect. There were stones bearing plough wounds, a few drassid spiders under them and here and there a fat white grub rolling helplessly about.

Next we passed through a patch of asparagus with its rounded fruit. Beyond this a clear little puddle was sighted over which dragon flies hovered, occasionally swooping down upon smaller insects. The far bank of the puddle was composed of sand and stones heaped together like conglomerate, but in front was a muddy flat upon which some frightened creature had dropped its animal prey.

In the flesh of this unfortunate we found a swarm of maggots, young flies whose duty it is to liquefy such objects and return death to life. Beneath the carrion a rove beetle lay in wait for unwary mother flies who came to lay their eggs in the game.

Leaving the pond for pastures new, we crossed a sandy field. Here several ant lions had made their pitfalls to entrap blundering ants, in whose formic acid they find nourishment and a pleasing flavor.

And so we might travel on and on, endlessly were it not for winter. Frosts are messengers of death in the insect world. Each drop of the mercury reduces its myriad life until at length there is nothing left. We witness the coming of the frosts, then the snows, exterminating all the little people that we have learned to know, for with winter comes the temporary death of their world. A queer little world that may be a fertile earth today and a barren moon tomorrow.

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Chapter II The Black Reed-wasp

Trypoxylon cinereohirtum, Cam

WHERE man has felled the primitive forest, obliterating nature's labors of half a thousand years, he leaves a wound that is long in healing. Just as a wound in the flesh leaves a scar that stands out distinct from its surroundings, so the forest heals its injury with a new vegetation, distinct from itself, but a mask nevertheless to the ghastly wound lying beneath.

We call the mask second growth. It is made up of trumpet trees, weakly shoots from fallen forest giants, great waves of razor-grass, briars, various types of undergrowth and here and there a patch of canes whose hollow stems are the natural nesting sites of the black reed-wasps.

Abandoning their natural habitat for the advantages afforded by Kalacoon,^ they flocked to our hospitable board, setting up their abodes in our pen-holders, in spools, nail holes, in the handle of my shaving glass, and, in fact, in anything that suggested a hollow tube with a tiny diameter.

To the general rule among Hymenoptera ^ the black reed-wasps are an exception. That is to say, they are neither social, in the usual community sense of the word, nor are they solitary. They came in mated pairs in search of nesting sites, inspecting all the best holes

^ A laboratory in the jungles of British Guiana where the author encountered the subject of this chapter.

^ An order of insects including ants, bees, wasps, etc.

in the house with great care and deliberation. Like so many newly married couples, filled with the enthusiasm of a novel project, they roamed about among the improved property that Kalacoon offered. To facilitate my studies of their life history, I placed several pieces of glass tubing, three or four inches long and a quarter of an inch in diameter, about the laboratory. I inserted the tubes, which were closed at one end, into pasteboard boxes, leaving the open end of each projecting, so that the entrances were in plain view, but the main part of the passages were quite dark, within the boxes. Thus I made conditions in the tubes exactly like those in the reeds that the insects naturally chose for their nests.

They were an instant success, and within an hour or two, all were occupied by enthusiastic couples. In the glass nests, I could watch everything that went on. All that was necessary for me to do in order to observe the occupants' behavior, was to remove the box covers, and replace them when I had finished.

True to the tradition of wasp history, the female proceeds with the hard labor of nest building and providing for her family. The male, while he never actually takes part in the work, sits menacingly in the entrance, during his mate's absence, guarding the nest from intruders of the same species that are ever-ready unbidden to acquire a partly prepared home. He shows great interest in the work, following the female into the tunnel, watching closely whatever she may be doing and squeaking continually in a high pitched key by vibrating his wings. This is a common habit among many wasps during work hours, but the species in question emits this strange little rasping sound during almost all of its occupations. I interpret it as an expression of pleasure or well-being, like a man who whistles at his job. The sound is never heard during fright or anger, but of this I shall treat in another chapter.

Upon occupying a tube, the female's first procedure is to place

THE BLACK REED-WASP 29

a plug of solid mortar in the end of it, doubtless to prevent parasites and ants from entering. This plug is two millimeters in thickness and composed of wet, light gray clay. It dries in a few hours, hardening into a tough cement. Next to this, a second plug, one millimeter in thickness, is placed, containing more moisture than the first and of a much darker shade. This is followed by a third one of the same description, placed five or six millimeters in front of the second plug, so that there is an air space between them which holds moisture in the nest. The tube is now provisioned with small spiders of different species, varying from five to eight in number, which are paralyzed by the wasp's sting and brought in one by one. They are packed tightly into the tube by the insect's broad head which is brought into use as a sort of ramrod. The tube is a tiny muzzleloader, into which she packs her living wads without mercy.

Upon the side or apex of the last, and usually the largest, spider's abdomen, she deposits a milky-white, bow-shaped egg, two millimeters in length. It is less than one-quarter as wide as long and closely resembles a sausage. The spiders and the egg are now enclosed in a substantial cell averaging twenty millimeters in length, by the insertion of a double plug of mortar, six millimeters in thickness, half of damp, dark-colored clay and half of the hard lighter material. The nest is now abandoned by the parent wasps who often start immediately to provision a second one.

In two days the egg hatches, bringing to light a yellow-white grub of thirteen segments. It commences feeding at once upon the spiders, a process which may be observed under the lens as a series of ripples or waves, commencing just behind the head and continuing the entire length of the body, — one wave being completed or spent, before the following one sets in. It grows rapidly, but very steadily, increasing each day in the same ratio until the last twenty-four hours of feeding, when it gains somewhat less than during the previous days.

In all, the larva or grub is full grown in four days from the time it hatches.

Upon finishing its meal, which lasts continuously for four days, the larva spins a flimsy net work of silken threads inside of which the cocoon proper is spun. This inner cocoon resembles a tiny torpedo, rounded at both ends and ten millimeters in length. It is very neatly constructed of delicate silk and coated all over the interior with a brown varnish that hardens in contact with the air.

Within this delicate cradle, ten days later, the budding wasp undergoes pupation — that wonderful process described more fully in the following chapter — by which the footless grub is transformed from a low and ancient form, to the highest order of modern insects. The actual change from gorged grub to a neatly folded, but colorless wasp is affected in ten days, but it still has three hundred and twenty-eight hours of confinement separating it from the light of day, hours which must be passed quietly, lest injury result.

As the hours go by, color at length flows through its body and appendages, transforming opaque yellow to glistening black. Then comes the final gift of nature, the power of motion. The nascent creature, moist with birth, bursts its cocoon, gnaws through the plug " of mortar and issues into the outer world a perfect insect. Only thirty-eight days have passed since I placed the tubes in the laboratory, and since the parents of this new creature arrived, realizing their destiny.

There is an interesting problem to solve concerning the black reed-wasps. Their nests vary considerably in number of cells. Some are complete with one, others contain two, but the majority are complete only after an egg has been laid upon the stores in three separate compartments. The question arises, How will the wasps emerge as perfect insects without disturbing one another?

If the nest is to shelter three insects, the cell farthest from the

Plough furrows are as mountain ranges to the insects