Roundworm

“ Once such an insect is caught on one of the threads it is lost beyond all hope. There it sticks, struggle as it may. The vibrations caused by its struggles attract the attention of the glow worm which quickly winds up the hanging thread. If it is not hungry at the moment it has been observed to play with its victim, [Pg 5] drawing in and then letting out the line after the manner of a fisherman. Finally the prey is drawn into the silken sheath and entirely devoured, chitinous shell and all. It is not merely sucked, as is the fashion of the spider or the fly. ”

“ One of the most unusual of all luminous creatures is an insect larva found by farmers ploughing damp soil in Brazil and Uruguay. It is a reddish-brown little worm with rows of green lights on both sides and a vivid red lamp on the front of its head. The red light is actually red—not white light shining through a reddish skin. Adult females of the species retain the same luminous pattern. Male adults have only feeble, yellow lights. The larva are extremely vicious little creatures, predators on white grubs which infest the soil. ”

“ He picks out the stones which are of proper size, and he fastens them together with mortar really as men do."
"Pray tell us of him, Uncle Philip."
"I will. The insect I mean is the caddis-worm, [Pg 73] which is to be found sometimes in ponds, and very often in springs of fresh water. There are several sorts of them, but the one I am thinking of now, builds a stone house to live in. These worms are in the habit of making a little tube, sometimes of sand, or shell, or wood, or leaves, or stones, to live in; and their skill consists in joining these perfectly, and making them stick together. ”

“ The hair-worms certainly present the appearance of long, delicate black hairs, which move about with great activity amid the mud of pools and ditches. These worms, in the early stages of their existence, inhabit the bodies of insects, and may be found coiled up within the grasshopper, which thus gives shelter to a guest exceeding many times the length of the body of its host. Sooner or later the hairworm, or Gordius, as the naturalist terms it, leaves the body of the insect, and lays its eggs, which are fastened together in long strings, in water. ”

“ The majority of these larvae live in decaying wood, but some are found in the earth; as a rule the growth is extremely slow, and the life of the larva may extend over two or more years. Some obscurity has prevailed as to their food; it is now considered to be chiefly flesh, though some species probably attack decaying roots; and it is understood that wire-worms destroy the living roots, or underground stems, of the crops they damage. ”

“ I need only mention the canker worm and American tent caterpillar, and the various kinds of cut worms, as instances.
43. Parasite of the American Silk Worm.
We must not, however, forget the good done by insects. They undoubtedly tend by their attacks to prevent an undue growth of vegetation. The pruning done to a tree or herb by certain insects undoubtedly causes a more healthy growth of the branches and leaves, and ultimately a greater production fruit. Again, as pollen-bearers, insects are a most powerful agency in nature. ”

“ Some doubts have occurred as to the food of the glow-worm. From actual observation, it has been ascertained that its larvæ feed on snails, decayed worms, &c., and are decidedly carnivorous. Neither old nor young touch plants as food. The larvæ are very voracious in their habits; but it is supposed that the perfect insect eats but little. If it does eat, it probably feeds on animal substance.
The female is without wings, and is far more luminous than the male. ”

“ Very good illustrations of this kind of work are afforded by the rascal leaf-crumpler and the common bag worm, both of which in the larva state live in cases, and are much affected by parasites, and neither of which can survive if the cases are plucked in winter and placed away from any trees or shrubs, while under these circumstances the parasites will perfect and escape.
It is quite different with the second method of dealing with beneficial insects which I have mentioned, for here man has an opportunity of doing some very effective work. ”

“ As they leave the bodies of their hosts they fall to the ground, and crawl away into the deeper and moister parts of the soil. Threadworms found in the damp earth, in digging up gardens and cutting ditches, have often been brought to me, which presented no external distinctions from the threadworms of insects. This suggested to me that the wandering threadworms of insects might instinctively bury themselves in damp ground, and I therefore instituted a series of experiments by placing the newly-emigrated worms in flower-pots filled with damp earth. ”

“ Earth-worms are more plentiful in moist land, such as pastures, etc., than in that which is cultivated; in gardens, also, they exist in vast numbers. When it is desirable to take worms in quantities, it is only necessary to thrust a stake or three-pronged fork into the ground, to the depth of about a foot, and to move it suddenly backward and forward, in order to shake the soil all around; the worms are instinctively terrified by any motion in the ground, and, when disturbed, hasten to the surface. ”

“ Several species of earth-worms are common in St. Catharina in South Brazil, and Fritz Müller informs me “that in most parts of the forests and pasture-lands, the whole soil, to a depth of a quarter of a metre, looks as if it had passed repeatedly through the intestines of earth-worms, even where hardly any castings are to be seen on the surface.” A gigantic but very rare species is found there, the burrows of which are sometimes even two centimeters or nearly 0.8 of an inch in diameter, and which apparently penetrate the ground to a great depth. ”

“ Everything suits them: ornamental plants and edible plants alike, flower-beds, market-gardens, and plants in fields. When a seedling withers without apparent cause, draw it to you gently; and the dying plant will come up, but maimed, cut from its root. The Gray Worm has passed that way in the night; its greedy jaws have cut the plant. It is as bad as the White Worm, the grub of the Cockchafer. When it swarms in a beet-country, the damage amounts to millions. This is the terrible enemy against which the Sand-Wasp comes to our aid. ”

“ As the acids of the food tube act upon the mineral grains that pass through it, the earthworm renders great aid in forming soil. By burrowing it makes the soil more porous and brings up the subsoil.
Although without eyes, the worm is sensitive to light falling upon its anterior segments. When the light of a lantern suddenly strikes it at night, it crawls quickly to its burrow. Its sense of touch is so keen that it can detect a light puff of breath. ”

“ What advantage the worms derive from plugging up the mouths of their burrows with leaves, &c., or from piling stones over them, is doubtful. They do not act in this manner at the times when they eject much earth from their burrows; for their castings then serve to cover the mouths. When gardeners wish to kill worms on a lawn, it is necessary first to brush or rake away the castings from the surface, in order that the lime-water may enter the burrows. ”

“ There are parasitic plants that flourish only on trees of some few species, and others that have particular animals for their habitats—as the fungus which is fatal to the silk-worm, or that which so strangely grows out of a New Zealand caterpillar. Of animal-parasites various kinds lead lives involving specialities of distribution. We have kinds which use other creatures for purposes of locomotion, as the Chelonobia uses the turtle, and as a certain Actinia uses the shell inhabited by a hermit-crab. ”

“ The very name Earthworm, so distinctive as it is of the habitat of these animals, seems to have been expressly invented in order to crystallise into one word the remarkable distributions of these creatures. They are with very few exceptions the most purely terrestrial animals that we know. There are a few Mammals like the mole and several underground Amphibians and Snakes in the tropics which share this habitat with the worms, probably because they chiefly prey upon them. But there is no group of animals that is characterised by a subterranean existence in the way that earthworms are. ”

“ The colour is saturated green, the eyes are transformed into round, projecting shiny black beads, and the head is erect. The ludicrously dreamy, complacent look has given way to wide-awake alertness. They take all kinds of living food. When they find an earthworm, they first look at it, bending the head sharply down, lift themselves upon the fore-limbs and then pounce upon it, nipping the prey with the jaws, and then poking it down deliberately with the hands. ”

“ Earth-worms are distributed throughout the world under the form of a few genera, which externally are closely similar to one another. The British species of Lumbricus have never been carefully monographed; but we may judge of their probable number from those inhabiting neighbouring countries. In Scandinavia there are eight species, according to Eisen; [8a] but two of these rarely burrow in the ground, and one inhabits very wet places or even lives under the water. We are here concerned only with the kinds which bring up earth to the surface in the form of castings. ”

“ During the day they remain in their burrows, except at the pairing season, when those which inhabit adjoining burrows expose the greater part of their bodies for an hour or two in the early morning. Sick individuals, which are generally affected by the parasitic larvæ of a fly, must also be excepted, as they wander about during the day and die on the surface. After heavy rain succeeding dry weather, an astonishing number of dead worms may sometimes be seen lying on the ground. ”

“ Earth-worms abound in England in many different stations. Their castings may be seen in extraordinary numbers on commons and chalk-downs, so as almost to cover the whole surface, where the soil is poor and the grass short and thin. But they are almost or quite as numerous in some of the London parks, where the grass grows well and the soil appears rich. Even on the same field worms are much more frequent in some places than in others, without any visible difference in the nature of the soil. They abound in paved court-yards close to houses ”

“ The feeling conveyed is that there are no scales: that the external coat is continuous and homogeneous; and one marvels at the reptile's power of gliding rapidly through the fingers. Though the Slow-worm may be found on the edge of the wood, or on the heath, sunning itself early in the spring, and apparently a lifeless casting in bronze, on the slightest alarm it dives into the vegetable soil and speedily disappears. ”

“ Earthworms live underground in burrows that are sunk well below the frost line. In digging they work head downward, gnawing—although they have no hard jaws—and swallowing the earth that is not easily crowded aside and then throwing it out and perhaps heaping it up as "castings." The tunnel must be wide enough to let its occupant turn around in it, and it ends in a deep chamber in which one or more worms may pass the winter without freezing. These worms naturally seek a loose, damp soil, not only for ease of working, but because moisture is a necessity, as they breathe through their skin ”

“ Although worms cannot be said to possess the power of vision, their sensitiveness to light enables them to distinguish between day and night; and they thus escape extreme danger from the many diurnal animals which prey on them. Their withdrawal into their burrows during the day appears, however, to have become an habitual action; for worms kept in pots covered by glass plates, over which sheets of black paper were spread, and placed before a north-east window, remained during the day-time in their burrows and came out every night ”

“ Worms newly freed from their exuviæ are easily distinguished from others by the pale color and wrinkled appearance of their new skin. This latter quality, however, soon disappears, through the repletion and growth of the insect, which continues to feed during five days. At this time its length will be increased to half an inch; when it is attacked by a second sickness, followed by a second moulting, the manner of performing which is exactly similar to the former. ”

“ The earth-worms never behave so ill. The “worms” that people mean, when they speak of this harm done, are the grubs or larvæ of some insects, as of the daddy-long-legs and others.
These grubs and cut-worms will eat living plants, but Mr. Worm likes dead leaves and stems best. He wants his food made soft by decay.
Now we come to the chief work of the true earth-worms. When they make their halls and houses, they fill their long bodies with the earth. Some say it is their food. ”

“ Inasmuch as in every case the Lumbricidae from non-European countries are identical with European species, since it has been shown that these animals are very readily introduced accidentally with plants, &c., and in view of the fact that they are impatient of sea water, it seems clear that the presence of these Lumbricidae in other continents is due to accidental transportation. Most earthworms live in the soil, which they devour as they burrow through it. ”

“ The food of the Slow-worm must of necessity be very small, for the mouth not being dilatable, as in the true Snakes, it cannot possibly receive such prey as Frogs, Toads, and Rats, which have been absurdly assigned to it. Professor Bell has found insects in its stomach, and M. de Sept Fontaines asserts that it will readily feed on earth-worms, even of six or seven inches in length. ”