It must have been a very dead ditch in which you held your first hunt, or among the spoils is one, or perhaps more than one, large, dark olive-green beetle. I must now assume that you can tell by a not too small insect whether it is a beetle; besides, the hard shields, which cover the top of the abdomen and with it the wings, are a fairly easy feature of the vast majority of beetles; that is why they are also called coleopterous insects in the textbooks.
Now see if the great beetle which you have caught has[ 26 ]the following description matches; this is more than likely, because the beetle, which I mean, the Banded Water Beetle, is almost everywhere. Separate it in a small bottle for easy comparison (fig. p. 7 ).
As has been said; its color is olive green, almost black, it gleams in the sun with a purple or red hue; its length is about 3 cm; its width will be 2; much more not, or it is a different species. His name will immediately be explained to you, if you notice the yellow frame of the bust; the elytra are not completely surrounded by the yellow band: it tapers towards the top of the shields, that is, towards the tip of the abdomen, and disappears just before the greatest width.
Those elytra provide a means of distinguishing the females from the males. In the males they are smooth and shiny; in the females, on the other hand, this brilliance is dulled by a number of furrows or furrows, which run parallel to the wing seam from the bust and become progressively shallower towards the posterior end; so that about a third of the shields, counted from the tip of the abdomen, are smooth in the females as well. Yet, on close inspection, you can also distinguish a few rows of dots or dimples on the shields of the males.
If you look at the animal from below, it appears to be almost entirely yellow there, and you detect a wobbling of limbs, which at first glance is inconceivable.
When the beast stands still for a moment, you distinguish 3 pairs of legs, (although a characteristic of an insect, at least in an adult animal) and between them a formidable weapon of defense or attack of our beetle, a short two-pointed spear; try its sharpness on your finger.[ 27 ]
Perhaps you thank you for taking the animal alive in your hand—well, you can’t be blamed for that either; although you have not yet found that our fringed friend has a very ugly habit, which often helps him out, but does not please us , people with sensitive olfactory nerves, at least. But let’s not beat around the bush with fancy words; who wants to study nature should not be too dirty. He secretes, when he is cornered, at the edge of the breast shield and the abdomen a liquid, which gives off the most foul odor; if he has sprayed your fingers, you can just use green soap or soda, otherwise the stench will not be wiped off your hands all day long; clean water does not help.
If he has sprayed liquid once, he will not do so again at first; besides, it’s not poison, never let that fool you. If you will believe the farmers who see you create, all those ditches, even salamanders and frogs, are poisonous. You can also make our beetle spray, without letting yourself be sullied; for if you lay him on a smooth surface, so that he scratches wildly with his paws, without being able to move forward, and then gently tap him on the back.
But, though you are not frightened or vile, seizing our beetle might still make you make an ugly face. Besides the stinky fluid and the skewer on its chest, the fringed water beetle has another weapon that is not to be disrespected either. He delights in possessing a pair of jaws, which are a “nice to meet you!” can yell that you might say with a polite “ouch, ouch!” will answer. The pain does not last very long, and it does not bother you any further, a thousand to one, either. Yet, however brave I think you, I may not advise you to take the test; and i need you too[ 28 ]strongly advise against trying another. Those jaws, a few crooked hooks on the eye, usually don’t penetrate the skin, but it could well be the case with fine hands—and then one never knows what one is vaccinated with; such a brindle beetle is not very picky about his food, he may have eaten on an animal in a state of decomposition, and thus he might one day introduce contaminant into your blood with his jaws; which light can cause an ulceration.
Now you will perhaps remark that I am busy scaring you from the study of ditches, after having first imagined great pleasure in those observations. I would be very sorry if this were so; not that you made that remark, but that you were put off.
You understand that to avoid this I could have omitted the above light; yet I wanted to say it, even if the chance of infection is 1 in 1000; I heard only once that it happened; and I myself have often been bitten, without suffering any consequences.
Let it urge you to caution, without avoiding the investigation. Always grasp a beetle between thumb and finger, in its loins, and if it is one that exudes moisture, use tweezers rather; a double folded strip of tin is very suitable for this. Holding a beetle in the cupped hand never hurts; such an animal only bites when it feels itself to be grasped.
But let me not digress, there is so much to tell. It really pays to consider how the arrangement of our beetle—the whole body shape and the construction of the body parts themselves—are related to the way of life. Those two, way of life and arrangement, usually fit together so wonderfully that even [ 31 ]someone, who has not yet done much in nature study, can often infer from the interior much of the way of life.
Under the table: plant canister, landing net and bottle.
Even on a superficial view of the hull, one will have to recognize that there is hardly a more efficient form for movement over and through the water. From above the body is weakly arched, from below sloping towards the middle, and descending in a projecting frame, a keel, as in a ship. Head, chest and abdomen form a continuous mass; quite different from most land beetles, where constrictions occur between the three main parts. There is nothing to hinder his speed in the water. It is a light boat of elongate-ovoid shape, topped with a smooth, convex deck, which needs only a few oars to shoot through and over the water.
It is curious that in the same ditch or pool from which you have fished your beetles, you will find a still faster aquatic animal, which, in shape of top and bottom, is just the opposite of what is seen in the edged water beetle. seems effective.
It is the back swimmer (fig. 19); you probably also got it with the first shovel, because it is everywhere and in abundance in our country. Its beautifully yellow, gray and brown underside is convex, its darker upper side, on the other hand, is shaped like the underside of the ridged beetle, so blunt roof-shaped.
In connection with the foregoing, this can therefore be called ineffective, you will say. Wait a minute, that depends on the lifestyle. So take a look at that first. Scoop it out of the bottle with your full hand. Beware, he is as big a robber as the brindle, and though he has no jaws like this, he carries on his head a long, pointed awl, which he can pierce you deep into the flesh.[ 32 ]
Let’s rather use the tin pincers; that’s more sensible. Behold, now lay him straight on the water. seesaw! did you see that? He has thrown himself upside down with a little jump, and quickly swims down on his back. He almost always moves that way through the water; thus you see that in order to understand the efficient arrangement it is also necessary to know the way of life. Few ditches, unless it were the skater, (fig. p. 43 ) have such a fitting name as this backswimmer, and few such a singular way of moving about.
Oh, just to trace the way the aquatic animals move through or over their element is such an interesting study of nature. Take a hundred ditches of different kinds, and you will not find two that do it in the same way; as everywhere in nature, here is immeasurable richness of form and means, endless variety, which makes the study a pleasure.
But to any of your questions, how is this or that possible? eg, that the water snail creeps upside down against the sky or the surface of the water—you will not always be able to get an answer at once; it does not make the study of nature any less pleasant, however, that there are still so many riddles to be solved.
Sometimes you cannot find a name for a mode of locomotion.
Thus there is a golden-green, elongated land beetle, or rather a shore beetle, whose larvae pupate under water; His name is Donacia (see drawing p. 19 ); you will find it in May among hundreds of reeds; in a little book (following this) we shall perhaps discuss him at length with animals which are more common on the ditch-side, such as frogs, grass snakes, etc.; take a look[ 33 ]something to note. When this little creature, newborn, comes up, it moves in an indescribable way over the water to the shore; though you throw ten back into the water to see how it goes, you cannot name it; it is no swimming, no drifting, no flying, no rowing, no running, no sliding—it is all at once and yet something else.
But to return to our edged beetle and backswimmer. I said they were boats that needed only a few oars to be perfect.
And those oars are not missing. A look at the hind and middle legs, or rather at the feet of those legs, will teach you at once what they are for; however strange it may at first seem to you, to watch closely a swimming insect, you will find in it much like the swimming feet of a swan or a frog. Just as these excellent swimmers, in the backstroke that propels them, spread their webbed feet wide—and in the retrieval of the leg the webs collapse to minimize the drag of the water—so does the double-rowed water beetle act. hairs, close together like the beard of a feather, on his hind and middle feet. During the thrust stroke the rows of hairs spread out into a step, when drawn in they collapse into a thin membrane,
When we row a little boat, we take the oars out of the water on the return, that is just as effective; but if one day a man wanted to make a Jules Verne-style boat to row underwater like our beetle , he could do no better than to use the row-legs of the brimmed beetle as a model for his oars.
The chip must then be lengthwise, but only to one[ 34 ]side, can snap together on the hinges and fold open on recoil. Such a trowel can really be made, and can also be used with advantage with our ordinary rowing boats. Who knows, one of you might even invent an improved rowing method! Men have learned to sail and steer and swim from the birds, fish and frogs, why should not our beetle or the backswimmer, in turn, teach men a new way of rowing.
That the edged water-beetle can swim nimbly, though it is not the swiftest of rowing insects, you notice when, in a not-too-large water-bowl, it hunts for a stickleback; in spite of the much more complex mechanics of the swimming apparatus of that swift little fish, it loses out to the beetle. When he has caught up, the rowing feet are put out of service, the middle and forelegs become pincers,—Look at the thorns and claws they have,—and the crooked jaws begin their murderous work.
The males of the water-edged water beetle have another formidable means of preventing such slippery prey from escaping, in case the legs or jaws cannot get a grip so soon—among other things, on the smooth, hard scales of a fish. Two tars of the foot of the forelimbs are widened into a disc; this acts as a suction cup; it works in much the same way as the piece of leather on a rope with which you can lift stones from the street. The females do not have this disc, and can be distinguished from the males by this lack (even better than by having grooves in the elytra), because females have been found without or almost without grooves, but never with adhesive discs on the legs. . Those discs are easy to examine on a dead specimen, and then it turns out[ 35 ]it is that such an instrument is composed again, and consists of a number of small and one large suction cup, or rather: ‘sticking disc’.
That these adhesive discs have yet another service to perform may be deduced from the fact that only the males possess them. The females can also handle a fish.
If you hold out a small piece of flesh to your beetle while it floats dead still on the surface of the water, you notice that the sight of the beast does not appear to be particularly sharp; it does not move as long as you do not move it; but now touch one of his two blades with your piece of flesh—the long threads at the front of the head—and at once he strikes the claws of one of the forelegs into the flesh; he suddenly bends the foot so that the piece is pressed against the adhesive discs, and quickly rows it to the bottom to munch it on at his leisure.
Now try the same with a piece of bread or a piece of fruit, the beetle does not like it; if you make it too much trouble for him, he will dive without heeding the crumbs you throw after him. He stirs up the sand from the bottom of your bottle; if he succeeds in catching a worm there, you will see him in his gluttony; while the animal holds its head up a little more than when it is at rest, the jaws become clearly visible; they work from right and left to each other, not from top to bottom, as with the larger animals and with us.
You notice that his teeth are excellently arranged, if you notice how quickly he devours a dead thorn. In our beetles, however, this arrangement is more complex than appears superficially. A description of it will not be able to make it clear to you—I’m afraid—but perhaps it will work if the accompanying drawing, which has been greatly enlarged,[ 36 ]takes it, and at the same time seeks out the designated parts of a dead beetle. A good loupe is not superfluous.
Mouthparts of a beetle.
Mouthparts of a beetle.
If things get too complicated for you, skip these two pages; but if you think of setting up a beetle collection in time, better put in some effort; for very often particulars of the mouth implements of a beetle serve in the determination of the species.
Like all good things, those mouth implements come in threes. For the sake of clarity, the drawing shows the head of a ground beetle, whose jaws protrude far forward, seen from below. Here each of the parts has been given its own hue; the two circular upper jaws form the background of the drawing—they are white and dotted; at the top of those jaws you see inwardly sharp teeth or jaws. The two lower jaws lie over it : everything that is darkest (black) tinted in the drawing belongs to those lower jaws. The third division, (again lighter) runs partly across it; that’s the bottom lip .
A lower jaw.
A lower jaw.
A lower jaw.
A lower jaw.
The (dotted) upper jaws are not further articulated; they, like the two blades of a pair of scissors, move towards each other, and serve to seize, kill and retain the prey.[ 37 ]
The lower jaws (black), however, are so much more compound. Each half of such a mouth part consists of a lower part: the root (indicated with w on the right half of the drawing ); then the thick handle ( st ) can move a little to the right or left. Sprouting from the top of that stipe, directed outwards: the jaw probe ( kt. ) and, directed inwards, an inner jawpiece ( k ). That inner piece is provided with stiff, horn-like pins, which process the food before it passes through the throat. The service of the jaw probes ( kt) cannot yet be stated with absolute certainty. They are constantly in motion when eating, the pitch-black beetle and also the edged water beetle keep bringing them into contact with the food. Perhaps they contain senses of taste. As if that wasn’t complicated enough, a second set of jaw probes ( kt′ ) can be found on the inner jawpiece of many beetles .
The third section (the lower lip) is also already articulated. It consists of: the chin k , on top of which the actual lip with the tongue l , and this sends out another articulated feeler ( lt ) to the right and left , called lip feeler.
The lower, untinted part of the head is the horn-like throat piece.
The jaw system in the various beetle species is essentially the same as that described. Now for practice look up the corresponding parts on the two small, separately drawn lower jaws of a few other beetles. Then you immediately notice some small deviations. Thus, in one on the left, the inner jaw probe ( kt′ ) is provided with its own stem, and the inner jaw portion has a supporting extension that extends to the root ( w ). The other mandible (it belongs to a sandcrab) bears on that inner part ( k ) a movable tooth ( td ), and that part lies flush against the stipe ( st ) of the mandible.[ 38 ]
That has become quite an anatomy, but I hope that I have done a service to some of my readers who collect beetles, and to whom such names have hitherto been abacadabra.
If you have now discovered predators in your beetles from which no animal is safe in your bottles, you may think that another beetle of about the same shape, but an inch larger than the beetle, and which you may have seen at the same time as caught it, is an equally large monster.
And yet you are sorely mistaken; in nature you must always be prepared for surprises, and not be quick to draw a line from a few examples; that generalization might fool you here; perceiving alone can give truth. That other beetle, for which you search in vain for the yellow framing of the shields, and which therefore rightly bears the name of “pitch-black water-beetle,” has a different character from the rimmed one (see fig. p. 9 ).
They are as dissimilar in disposition as a half-feral domestic cat, who now and then goes birding, with the lobes of a Newfoundland or St. Bernard’s dog, who makes the wildest boys ride a horse on his back. without even grunting or showing his teeth.
Yet you cannot leave such a beetle in the bottle with your sticklebacks or salamanders without trial, it is possible that it will do them no harm. If you present him a piece of meat or egg white, in most cases he will politely thank you. If he does this, your big, thick pitch-black beetle, dangerous though it looks, is really a good-natured lob—biting the dummy does as good as never.
The way of life of the animals in the wild provides[ 39 ]sometimes strange, often contradictory phenomena. So it can happen that you find in your bottle or your aquarium a pitch-black water beetle, which likes meat and also hunts for spines or other fish, but the rule is that our beetle only eats plants or dead animals. It is also possible that he eats meat in the spring. One is not the other here.
His way of life is highly interesting; he has therefore become the object of study for many. He is, therefore, easy to study because he is not particularly quick in his movements, at least not nearly as agile as his neighbor the rimmed.
Immediately you notice a difference with these in the way of swimming. He does not knock out both his swimming legs at the same time, but rows with the legs alternately; this gives us the impression that he is walking or tripping through the water.
Also in this beetle species, the males are easy to distinguish from the females at first glance. As with the margin beetles, the males have adhesive disks on the front pair of legs, but of different shape; which are absent in the females. These females are also slightly larger than the males. The underside is not yellow, but appears greyish, because that side is denser and finer haired. Under water, through the air, that side seems to be silver plated; that silver sheen contrasts beautifully with the deep black of the upper body, making this beetle a desirable ornament for any aquarium.
If your aunt or grandmother has big, big goldfish, get her a pair of hydrophilus (that’s what the pitch-black is called in Latin, water lover means it) and add some water plants. But give a pair which you have been looking for a while, and which you are sure will despise meat-food, even in the spring. Otherwise they are never allowed in with the fishes.[ 40 ]
At first, your aunt might have a thing for those creepy critters. However, if you let her have a good look at them and set them aside so that they can do no harm to the fish, she will soon be at peace with your having set some silver, emerald, and black next to her gold. She will perhaps find as much pleasure in it as in the goldfish; especially now that she finds that the green makes her darlings live longer, become much more frisky, and that the water does not spoil so easily, even if she forgets to change it.
You will learn in the second half of this booklet what aquatic plants you should take, how you can obtain them and plant them, and also what that benefit for the fishes consists of. I will tell you this, that you have thus turned a torture prison into a piece of real nature.
When your Edged Torch just went to the safe depths with the morsel of flesh you offered him, you may have noticed that it took a bubble with it from the tip of its abdomen and let one or more escape along the way. If you watch your creatures from time to time, you will surely notice that the water beetles can stay under water for a very long time, but that they come every now and then to get some fresh air.
The gerande, however, does this in a very eccentric way; not with his head, but with his hindquarters he takes a breath. He takes that air down, as a reserve for breathing; and it also gives him a means of descending more slowly or more rapidly at will; for by ejecting air he can suddenly make himself much heavier. He therefore proceeds in much the same way as an air traveler, releasing gas.
Where the beetle stores that air? Well, the gently arched elytra forms a roof over his abdomen,[ 41 ]that has enough space to hold a hefty stock. The edges of this roof fit very well around the slightly raised lateral edge of the body; and that edge is furthermore provided with a row of fine hairs which prevent the ingress of water . Only at the extremity of the body do you see a fine opening in a dead beetle; that opening, however, is closed in the living, in the water, by an air bubble; also the two halves of the roof, the two elytra, close watertight against each other in the middle of the back, so that the seam between them appears only as a fine line.
Strange as it may seem to you, yet it is true that without this curious arrangement our water-beetle would drown in its own element.
Lift those elytra and close to the lateral edge of the body, on either side you see fine elongated openings, which are the breathing openings—his nostrils, so to speak. Through these slits enters the breathing air, passing further through branching tubes, supplying the whole body.
Now the beetle wants to get some air, then it brings its abdomen to the surface, it lifts the elytra for a moment and immediately closes them again; if he presses those shields strongly against the resilient hairs when descending, he can let as much air escape through the opening as he wants to get rid of. The remaining air bubble on its abdomen is thus related to the air above the breathing openings.
This arrangement saves our beetle from suffocation and drowning. In it he also has a means of reaching the safe bottom quickly in the event of danger; there it is among the dark aquatic plants, because of its own dark color, difficult to distinguish for its enemies: pike and perch, heron and stork.[ 42 ]
But what about the pitch black one? It doesn’t come up nearly as often and never with its hindquarters, but with its head. Does it breathe like we humans do? No, as far as I know there is not a single insect that breathes through the mouth. They only use their beaks to take in food. But how? Well, careful observation is the only means of finding out, or at least getting on the way to the truth. If there is still something to clarify, then we ask the naturalists.
Examine first whether your pitch-black beetle brings the whole head to the surface. No, isn’t it? Only one of the blades, now the right, now the left. And strangely, he first puts them above the water and immediately , then he knocks the top half of them, that thick knob with a few more limbs, down back into the water; the blade seems broken, and the fracture touches the surface.
So far the observation is quite easy, but now further. You and I are already satisfied when we have come so far that we know that that pitch-black one takes the air in that strange way with his blades.
But the naturalists do not stop at such a thing, they must know the intricacies of the matter, the how, the wherefore, and by what means; and they found out. He who first found the seam of this stocking has had a lot of troubles and troubles with it; You can convince yourself of that, if you want to make the effort, with the help of the accompanying drawing, to check out that remarkable arrangement.
The figure on the left represents the blade at rest, the other in the breathing position. The sections 7, 8 and 9 thereof[ 43 ]are knocked down, 6, 5, 4, 3, 2, and the root member 1, which is attached to the head, have remained erect; the upper limbs 9, 8, 7, are distinguished from the others, as you see, by strong hairs and projections; the air hangs between them, the three of them form a tube; the top part 7 thereof touches the surface of the water; the lower end—the tip of the last ( 9th) member of the blade—is slightly submerged; the arrow points the way of the air current, which is carried to its terminal point by movements of the limbs of the blade. Now that terminus brings the beetle under the rim of the breast shield, where the largest breathing openings are, and so fills the air tubes in its body; or he carries a supply of air to the underside of his body, where a good amount may be hidden among the long, silky hairs.
Blades of the spinning water beetle; right while breathing.
Blades of the spinning water beetle; right while breathing.
It is that air that silvers the beetle’s belly under water. On none of the eleven parts of the blade of a rimmed water beetles do you notice anything like it; they get a little shorter towards the end; only the last member is a bit elongated and budding.[ 44 ]
Why now the pitch-black has to draw in his life air in such a complicated way, very different from the rimmed? This is most likely related to the position of the air tube openings. In the rimmed, the largest and most lie on the back under the elytra, in the pitch black, as has been said, on the underside of the breast shield. Be that as it may, you can be sure that here too the way of life fits perfectly with the arrangement of the body.
Methinks you will see something more in our beetles than ghastly beasts by now; you must have acquired a little respect for the life of such curiously arranged animals, and with it respect for the creation, the whole Living Nature, in which they could develop in the course of centuries.
To admire and revere Living Nature, we don’t even need to dissect or examine it microscopically. Even a little more than superficial contemplation shows us all around us that wonderful correspondence, that harmony between the arrangement, between the colors and forms, and the way of life.
When we have made clear to ourselves the arrangement and significance of such a pair of blades or elytra for respiration, we are content with it, and it is wonderful enough for us—yet you can be sure that you are only lifted a corner of the veil which, for most people, conceals that wonderful institution.
Under those elytra you have no doubt found in your search a pair of brown membranous objects folded and partly turned inwards—the wings.
Wings? you ask now; what are wings for an animal that spends its whole life in water?[ 45 ]
Again a fine opportunity to point out the eternal connection between way of life and arrangement.
Where did you catch your beetle? In a standing water, a ditch, closed on two sides by a dam or a level crossing. But where will the beetle go and find its food, when the summer brings little rain and much heat? When the ditch dries out? Without those wings, his last refuge in that case, he would have to perish miserably. And where better, safer from damage or getting wet, could those indispensable resources be stored than in the watertight air chamber under the shields?
Even before the beetle is in need, because of drought or scarcity of food, it climbs up against a water plant or against the side of a ditch, whereby the thorny projections on the shins are of use to it; there he thoroughly pumps himself full of air, the hollow veins in the wings too; the twilight breaks, he spreads his wings, and seeks a good refuge. Growling, purring, as loud as a cockchafer, he sails with the wind behind the elytra, until he catches sight or nose of a pool of water that promises habitation and food; that nose is in the blades.
Thus it is that we often find our beetle in small and very shallow pools of water, in open cisterns or water barrels, sometimes in village gutters. In the dry summer of ’92, the walkers in the Utrechtschestraat in Amsterdam were repeatedly startled on warm evenings, and a whirring water beetle knocked off them.
People often force him to use his wings too. When the wide ditch behind the Leeuwenhoekstraat near the Staatsspoorstation was filled in a few years ago, the area around ‘t Amstelhotel teemed with all kinds of water beetles in the evenings. They flew against the balloon of the electric light and fell to the ground.[ 46 ]
The boys of my class brought several alive in the morning, both different kinds of brindles, as well as the large and the small pitch-black.
Now you know at once that you must cover your aquarium towards evening, if you are not fond of such a move of your prisoners.
A gardener told me long ago that he often found great water-beetles on the glasses of his greenhouses, lying there thrashing about on their backs. Perhaps those beetles have mistaken the glasses, glistening by the setting or rising sun, for a pool of water.
If you have found room in your tank of edged water beetles for a few aquatic plants with fairly thick stems, you may be lucky enough to have one of the captive beetles give you something else to see.
Watch carefully the movements of the females; if you see them from time to time clinging to a stalk with their forelegs , pulling the swimming legs obliquely upwards, and the hindquarters bending violently or moving quickly, then they intend to lay eggs. If the prison is not too inconvenient, or not wholly devoid of aquatic vegetation, they take what little there is for granted and begin the task of ensuring the survival of the species.
The tip of the abdomen is strongly extended; two pointed blades emerge, and between them a small ovipositor, with which a slot or hole is inserted in a stem: in or near each hole, which is difficult to distinguish, an egg is fixed. Not many, a thirty at most, at least in captivity. The eggs are sometimes white, sometimes orange, sometimes red, elongated and relatively large: 2 to 3 millimeters.