Insects of the Thames
Except among the select few, generally either enthusiastic boys or London mechanics of an inquiring mind, who keep fresh-water aquariums and replenish them from ponds and brooks at “weekends,” few persons outside the fancy either see or know much of the water insects, 1 or are aware, when floating on a summer day under the willows in a Thames backwater, of the near presence of thousands of aquatic creatures, swift, carnivorous, and pursuing, or feeding greedily on the plants in the water garden that floats below the boat, or weaving nests, tending eggs, or undergoing the most astonishing transitions of form and activity, on or below the surface. Many of them are perhaps better equipped for encountering all the chances of existence than any other creatures. They can swim, dive, and run below water, live on dry land, or fly in the air, and many are so hardy as to be almost proof against any degree of cold. The great carnivorous water-beetle, the dytiscus, after catching and eating other creatures all day, with two-minute intervals to come up, poke the tips of its wings out of the water and jam some air against its spiracles, before descending once more to its subaqueous hunting-grounds, will rise by night from the surface of the Thames, lift again those horny wing-cases, unfold a broad and beautiful pair of gauzy wings, and whirl off on a visit of love and adventure to some distant pond, on to which it descends like a bullet from the air above. When people are sitting in a greenhouse at night with no lamp lighted, talking or smoking, they sometimes hear a smash as if a pebble had been dropped on the glass from above. It is a dytiscus beetle, whose compound eyes have mistaken the shine of the glass in the moonlight for the gleam of a pond. At night some of the whirligig beetles, the shiny, bean-like creatures seen whirling in incessant circles in corners by the bank, make a quite audible and almost musical sound upon the water. The activity of many of the water insects is astonishing. Besides keeping in almost incessant motion, those which spend most of their time below water have generally to come up constantly to breathe. Such are the water-bugs, water-scorpions and stick insects, which, though slender as rushes, and with limbs like hairs, can catch and kill the fry of the smaller fishes. Most of these are like divers, who have to provide themselves with air to breathe, and work at double speed in addition.
If a group of whirligig beetles is disturbed, the whole party will dive like dabchicks, rising to the surface again when they feel the need for breathing-air again. The diving-bell spiders, which do not often frequent the main Thames stream, though they are commonly found in the ditches near it, gather air to use just as a soldier might draw water and dispose it about his person in water-bottles. They do this in two ways, one of which is characteristic of many of the creatures which live both in and out of the water as the spider does. The tail of the spider is covered with black, velvety hair. Putting its tail out of the water, it collects much air in the interstices of the velvet. It then descends, when all this air, drawn down beneath the surface, collects into a single bubble, covering its tail and breathing holes like a coat of quicksilver. This supply the spider uses up when at work below, until it dwindles to a single speck, when it once more ascends and collects a fresh store. The writer has seen one of these spiders spin so many webs across the stems of water plants in a limited space that not only the small water-shrimps and larvae, but even a young fish were entangled. The other and more artistic means of gathering air employed by the spider is to catch a bubble on the surface and swim down below with it. The bubble is then let go into a bell woven under some plant, into which many other bubbles have been drawn. In this diving-bell the eggs are laid and the young hatched, under the constant watch of the old spider. Few people care to take the trouble to gaze for any time into a shallow, still piece of water, in which the bottom is plainly discernible, and a crop of water-weeds makes a wall on either side of some central “well.” If they do find some such pond near the Thames banks or a shallow backwater, they may see after a few minutes much that is new and suggestive of strange activities. Everything will be quiet and motionless at first, for water beasts are very suspicious of movement above them, and all sham dead, or lie quite still, and are strangely invisible. On the other hand, they have none of the power of remaining motionless for half-an-hour like land animals. Soon what look like sticks, but are caddis larva, begin to creep on the bottom. Then more brown objects, larvae of dragon-flies and water-beetles, detach themselves from the stems of the plants and cruise up and down seeking what they may devour. Other creatures feeding and swimming among or beneath the plants crawl out on to the upper surface, and the water-beetles come up to breathe, or to play upon the surface. One of the largest of these is a very fine black beetle, a vegetable-feeding creature. It is most interesting to see two of them—they generally live in pairs—browsing on one of the fern-like plants of the Thames. This plant has leaves like fern blades, each having in turn its own small spikelets. The big beetles work along the leaf like a cow in a cabbage yard, biting off, chewing, and swallowing each in succession, and leaving the stem perfectly bare. Sometimes it looks as if the two beetles were eating for a match, like the beef-eating contests held in country public-houses, in which the winner once boasted that he won easily “afore he came to vinegar.”
The number of carnivorous creatures found in the water seems out of all proportion to the usual order of Nature. But this is perhaps because the minute, almost invisible creatures, or entomostraca, of which the rivers and ponds are full, and which are the main food of the smaller water carnivora, live mainly on decaying vegetable substance, which is practically converted and condensed into microscopical animals before these become in turn the food of others. It is as if all trees and grass on land were first eaten by locusts or white ants, and the locusts and white ants were then eaten by semi-carnivorous cows and sheep, which were in turn eaten by true carnivora. The water-weeds, both when living and decaying, are eaten by the entomostraca, the entomostraca are eaten by the larvae of insects, the perfect insects are eaten by the fish, and the fish are eaten by men, otters, and birds. Thus we eat the products of the water plants at four removes in a fish; while we eat that of the grass or turnips only in a secondary form in beef or mutton.
The water-shrimp is a very common crustacean in the small Thames tributaries, and valuable as fish food. It has a very rare subterranean cousin known as the well shrimp. A lady in the Isle of Wight, who in a moment of energy went to the pump to get some water to put flowers in, actually pumped up one of these subterranean shrimps into a glass bowl. The well was eighty feet deep. The shrimp was absolutely white, and probably blind.
Flesh-eating insects are fairly common on land; wasps will actually raid a butcher’s shop, and carry off little red bits of meat, besides killing and eating flies, spiders, and larvae. Dragon-flies are the hawks of the insect world, and slay and devour wholesale, when in the air as well as when they are larvae on the water, though few persons actually witness their attacks on other creatures, owing to the swiftness of their flight. Some centipedes will attack other creatures with the ferocity of a bulldog. An encounter between one of the smaller centipedes and a worm is like a fight between a ferret and a snake, so frantic is the writhing of the worm, so determined the hold which the hard and shiny centipede maintains with its hooked jaws. But the ferocity and destroying appetite of some of the water creatures would be appalling were it not for their small size. The desire of killing and devouring appears in the most unexpected quarters, among creatures which no one would suspect of such intentions. Of two kinds of water snail found in the Thames, and among the commonest molluscs, one is a vegetable feeder. It is found living on water plants, the snails being of all sizes, from that of a mustard seed to a walnut. The other will feed not only on dead animal substances, but on living creatures, and is equipped with sharp teeth, which work like a saw. One of these kept in an aquarium fastened on to and slowly devoured a small frog confined in the same vessel. The large dytiscus beetle is the great enemy of small fish. If the salmon is ever restored to the Thames these creatures will be among the worst enemies of the fry, though in swift rivers they are not plentiful. Frank Buckland states that in Hollymount Pond they killed two thousand young salmon. One of these was put into a bowl with a dytiscus beetle, which, “pouncing upon him like a hawk upon an unsuspecting lark, drove its scythe-like horny jaws right into the back of the poor little fish. The little salmon, a plucky fellow, fought hard for his life, and swam round and round, up and down, hither and thither, trying to escape from this terrible murderer; but it was no use, he could not free himself from his grip; and while the poor little wretch was giving the last few flutterings of his tail, the water-beetle proceeded coolly to peck out his left eye, and to devour it at once.” The larva not only of the carnivorous dytiscus but also of the vegetable-feeding water-beetle are ferocious and carnivorous, and deadly enemies of young fish and ova.
“Now when you’ve caught your chavender,
(Your chavender or chub)
You hie you to your pavender,
(Your pavender or pub),
And there you lie in lavender,
(Sweet lavender or lub).”
Mr. Punch.
I went into the Plough Inn at Long Wittenham in mid-November to arrange about sending some game to London. The landlord, after inquiring about our shooting luck, went out and came back into the parlour, saying, “Now, sir, will you look at my sport?” He carried on a tray two large chub weighing about 2-1/2 lbs. each, which he had caught in the river just behind the house. Their colour, olive and silver, scarlet, and grey, was simply splendid. Laid on the table with one or two hares and cock pheasants and a few brace of partridges they made a fine sporting group in still life—a regular Thames Valley yield of fish and fowl. The landlord is a quiet enthusiast in this Thames fishing. It is a pleasure to watch him at work, whether being rowed down on a hot summer day by one of his men, and casting a long line under the willows for chub, or hauling out big perch or barbel. All his tackle is exquisitely kept, as well kept as the yeoman’s arrows and bow in the Canterbury Tales. His baits are arranged on the hook as neatly as a good cook sends up a boned quail. He gets all his worms from Nottingham. I notice that among anglers the man who gets his worms from Nottingham is as much a connoisseur as the man who imported his own wine used to be among dinner-givers.
Drifting against a willow bush one day, the branches of which came right down over the water like a crinoline, I saw inside, and under the branches, a number of fair-sized chub of about 1 lb. or 1-1/2 lbs. It struck me that they felt themselves absolutely safe there, and that if in any way I could get a bait over them they might take it. The entry under which I find this chronicled is August 24th. Next morning when the sun was hot I got a stiff rod and caught a few grasshoppers. Overnight I had cut out a bough or two at the back of the willow bush, and there was just a chance that I might be able to poke my rod in and drop the grasshopper on the water. After that I must trust to the strength of the gut, for the fish would be unplayable. It was almost like fishing in a faggot-stack. Peering through the willow leaves I could just see down into the water where a patch of sunlight about a yard square struck the surface. Under this skylight I saw the backs of several chub pass as they cruised slowly up and down. I twisted the last two feet of my line round the rod-top, poked this into the bush with infinite bother and pluckings at my line between the rings, and managed to drop the hopper on to the little bit of sunny water. What a commotion there was. The chub thought they were all in a sanctuary and that no one was looking. I could see six or seven of them, evidently all cronies and old acquaintances, the sort of fish that have known one another for years and would call each other by their Christian names. They were as cocky and consequential as possible, cruising up and down with an air, and staring at each other and out through the screen of leaves between them and the river, and every now and then taking something off a leaf and spitting it out again in a very independent connoisseur-like way. The moment the grasshopper fell there was a regular rush to the place, very different from what their behaviour would have been outside the bush. There was a hustle and jostle to look at it, and then to get it. They almost fought one another to get a place. Flop! Splash! Wallop! “My grasshopper, I think.” “I saw it first.” “Where are you shoving to?” “O—oh—what is the matter with William?” I called him William because he had a mark like a W on his back. But he was hooked fast and flopping, and held quite tight by a very strong hook and gut, like a bull with a ring and a pole fastened to his nose. I got him out too—not a big fish, but about 1-1/2 lbs.
This showed pretty clearly that where chub can be fished for “silently, invisibly,” they can still be caught, even though steam launches or row-boats are passing every ten minutes. This was mid-August; my next venture nearly realised the highest ambitions of a chub-fisher. It also showed the sad limitations of mere instinctive fishing aptitudes in the human being as contrasted with the mental and bodily resources of a fish with a deplorably low facial angle and a very poor morale. There was just one place on the river where it seemed possible to remain unseen yet to be able to drop a bait over a chub. A willow tree had fallen, and smashed through a willow bush. Its head stuck out like a feather brush in front and made a good screen. On either side were the boughs of the bush, high, but not too high to get a rod over them, if I walked along the horizontal stem of the tree. It was only a small tree, and a most unpleasant platform. But I had caught a most appetising young frog, rather larger than a domino, which I fastened to the hook, and after much manoeuvring I dropped this where I knew some large chub lay. As the tree had only been blown down a day before, I was certain that they had never been fished for at that spot.
I was right; hardly had the frog touched the water when I saw a monster chub rise like a dark salamander out of the depths. Slowly he rose and eyed the frog, moving his white lips as if the very sight imparted a gusto to the natural excellence of young frogs. I nearly dropped from the tree stem from sheer suspense, when he made up his mind, put on steam, and took it! He was fast in a minute, and kindly rushed out into the river, where I played him. Then I wound in my line and hauled him up till his head and mouth were out of the water. As there was an impenetrable screen of bushes between him and me I laid the rod down, trusting to the tackle, and ran round to where close by was a farm punt, made fast. It had been used during harvest time, and was full of what in the classics they call the “implements of Ceres.” All of these that do not seem made to cut your leg off are designed to run into and spike you. Besides scythes and reap hooks, there were iron rakes (sharp end upwards), wooden rakes, pitchforks, and garden forks, and the difficulty was to move in the punt without getting cut or spiked. The last users of the punt had also taken peculiar care to fasten it up. It was anchored by a grapnel, and by an iron pin on a chain, the pin eighteen inches long and driven hard into the bank. In a desperate hurry I hauled up the grapnel, did a regular Sandow feat in pulling up the iron peg, seized a punt pole apparently weighted with lead, but made out of an ash sapling, and started the punt. It would not move. I found there was another mooring, so picking my way among the scythes, spikes, rakes, &c., I hauled this in. It was most infernally heavy, and turned out to be a cast-iron wheel of a steam plough or other farming implement. Then I was under weigh, and got round to the fish. It was still there. I could see its expressionless eye (about as big as a sixpence) out of the water and its mouth wide open, when I remembered I had forgotten the landing-net in my hurry. Then came the period of mental aberration common to the amateur. The fish was certainly 4 lbs. in weight, yet I tried to get him in with my hands. Of course he gave one big flop, slipped out, and disappeared—the biggest chub I ever shall not catch.
Notes
1 In mentioning some of the Thames insecta I have also noticed some of the mollusca and crustacea. It is a pity these have not some common names. One cannot write easily of “pulmonate gasteropods.”