Henry Scherren

“ First of all the web is woven in a bell or thimble shape between the sprays of water-weed, or against the bottom or side of the aquarium. It is curious to notice how practices that must be necessary when the creature is at liberty are continued in captivity where they are useless. A web constructed in running water, or even in a pond or ditch, is liable to be swept away or to be emptied of air by a very slight current, so its owner has recourse to a system of guys and supporting threads, which are not required when the spider is safely housed in a small aquarium. ”

“ Sialis larvae occur in most ponds with muddy bottoms. They may be taken by scooping up some of the mud in a long-handled spoon—a most useful instrument for the collector—and washing it, or by throwing in the drag, and bringing to land a mass of water-weed, roots and all. A few may generally be detected near the roots. They may be picked up with a small pair of forceps, or with a brush, and dropped into a bottle; or, better still, into separate tubes; for they are fierce and voracious, and, failing other food, by no means indisposed to prey on each other. ”

“ If we watch a male Dytiscus in life, in a small aquarium, we shall soon be convinced that Lowne and Miall are correct in their statement that the cup-hairs discharge an adhesive substance. We shall see this all the more plainly if there is much floating vegetation. For, in swimming about, the Beetle will often come in contact with some of this, and it will adhere to the cup-hairs. His struggles to free himself from the encumbrance will show that the attachment is not altogether under his control. The offending weed is rubbed against the spines of one of the other legs till it is removed. ”

“ They will interest us while living in the aquarium, and when dead we can put them into pickle, and break them up at our leisure.
The broad shell of the Crab—the crab-cart of children—corresponds to the carapace of the Lobster, the Prawn, and the Shrimp, and bears the same number of appendages—fourteen pairs. To make out the pleon or swimming part, it is only necessary to lay the crab on its back, and, with a needle, or small knife, turn back the flap—or ‘apron,’ as fishermen call it—which lies in a groove on the under surface. ”

“ The larva will sometimes wave the abdomen up and down, just as one may see a Chironomus larva do when it has affixed its dwelling to the side of the glass, and this motion probably assists the process of respiration.
When the larvae have been watched under the conditions above described, I have never been able to detect independent motion of the gills. But it is better that every one should observe for himself, and draw his own conclusions from what he sees.
Now let us examine a specimen more closely with the lens, or under the dissecting microscope. ”

“ Sharp has compared to the action of a rower in feathering his oar. There is, however, this difference, which it is well to note. The oar is feathered after the stroke; the Beetle feathers its legs before the stroke. It is the first motion when it begins to swim, and the action is not peculiar to the male.
We now come to the third region, the abdomen. Like the thorax it is visibly divided into segments, though the division between them is not so great. Much difference of opinion exists as to the number of segments in the abdomen of a typical insect. ”

“ From Fig. 32 we may get a general idea of the appearance presented by a male or female, lying back upwards in a small glass dish, ready for examination with the pocket lens. The female may be distinguished at a glance by her wingless condition—only rudiments of wing-cases being present, and no wings—and her broader abdomen. In life she does not stand so high upon her legs as does the male, and her abdomen trails along the ground. The male does not acquire his wings till the last moult. ”

“ Prawns are exceedingly beautiful, and if we get hold of live specimens, from salt water or fresh, they should be put into an aquarium—the smaller, in reason, the better—so that their motions may be watched with the hand lens. If much weed be put in, the Prawns will use their walking legs in preference, while if there is little vegetation the powerful tail-fan will be employed for motion backwards, while the five pairs of limbs on the abdomen enable their owners to move forwards through the water. ”

“ Now let us put our larva into a small tube, and examine it more closely. The head is large and joined to the first segment of the thorax by a distinct neck. There are twelve small eyes, six on each side, a pair of antennae, two pairs of palps, and a large pair of sickle-shaped mandibles, which Swammerdam calls ‘teeth,’ and says that ‘it is perhaps to contain the muscles such teeth require that Nature has made the head so large.’ Behind the head come eleven segments, of which the first and last are the longest. ”

“ If, however, we wish to rear a beetle, the larva must be plentifully supplied with food, and removed from a bottle to a flat dish, where earth can be placed against the side so as to rise above the water-level. Fig. 77, where a pupa is represented in a bank by the side of a pond, will give us a hint how to go to work. The time occupied in pupation will vary according to the temperature of the room—but is never less than a fortnight. In the open it is probable that the winter is passed in the pupal condition, the perfect insect emerging in the spring. ”

“ It is always safe to look round the sides of the basin for the breathing-tube; if it is not detected in this situation, a glance along the surface of the tiny pools will probably show a break in the film. The Water Scorpion will not be far off.
That the insect really does cover itself with mud may be demonstrated by transferring it from the aquarium described to any shallow vessel, and allowing a fine stream of water—say, from a dipping-tube—to fall gently on it. The mud will be washed away, and in a few seconds will settle at the bottom. ”

“ The ‘Shrimps’—which, by the way, are not really Shrimps—will be dislodged from the weed, and we shall see them wriggling along on their sides, from which habit they and their near relatives are often called ‘Scuds,’ and ‘Screws.’ They are useful inmates of an aquarium, because they feed on decaying animal matter, and so keep the water pure and sweet. Opinions are divided as to whether these animals feed on water-plants; it is probable that when their natural food fails them, they take what comes in their way. ”

“ It is not a very easy matter to take this Beetle with a net, by sweeping in the ordinary way, for it likes to get into the middle of a mass of vegetation, where it is sure of a good food supply, and is probably safe from the attacks of Dytiscus, who not unfrequently makes a meal of his larger relation. A good plan is to pass the net under a mass of weed and then shake it to and fro in the water. ”

“ The only point to which attention need be called in examining the Water Boatman is its method of taking in a supply of air. In looking at a dead specimen we shall see a ridge or keel running down the middle of the under side of the abdomen, and fringed with hair on each side. A similar fringe runs along each side of the abdomen, thus forming two passages along which the air taken in at the end of the body is conveyed to the spiracles, the largest of which are on the thorax. ”

“ Dr. Sharp [63] says, ‘The wings [of the Hymenoptera] are remarkable for the beautiful manner in which the hinder one is united to the anterior one, so that the two act in flight as a single organ. The hind wing is furnished with a series of hooks, and the hind margin of the front wing is curled over so that the [171] hooks catch on to it. In some of the parasitic forms the wings ... have no hooks. The powers of flight, in these cases, are probably but small.’
If we were taking our subjects in consecutive order, the larva of Ptychoptera would properly come here, as being that of a Crane-fly. ”

“ The Pholcus, in spite of its size, is a weak creature, possessing little venom to dispatch its prey with, so that it makes a long and laborious task of killing a fly. A fly, when caught in a web, is a noisy creature, and it thus happens that when the Daddy longlegs—as Anglo-Argentines have dubbed this species—succeeds in snaring a captive, the shrill outrageous cries of the victim are heard for a long time—often for ten or twelve minutes. ”

“ An inch hand lens is quite sufficient to give a general idea of the hairy and spinous clothing of the legs and the position of the claws; but to see the teeth a higher power—a half-inch—will be necessary.
It is a good plan to choose a freshly killed specimen for the examination of its spinnerets. If the spider is laid on its back in a glass dish, gentle pressure on the abdomen away from the cephalothorax will cause the material secreted by the spinning-glands to ooze out. ”

“ Some or other of the members of this class are well known to everybody, if only in the shape of toothsome food—the Prawn, the Shrimp, the Lobster, the Crayfish, and the Crab. The great characteristic of this class of the Arthropod phylum is the so-called ‘shell,’ which differs greatly from true shell in being composed of chitine, hardened with salts of lime. Most of the species live in the water and breathe by means of gills or through the skin. In dealing with these creatures, some long words must be employed, if our present work on them is to be a stepping-stone to something more advanced. ”

“ As soon as the larvae reach the bottom they will walk round and round, giving us a good opportunity of watching them. In swimming—which may be backwards as well as forwards—the abdomen is waved from side to side. To see the backward motion one need only put a dipping-tube or a pencil, or the like, in front of the larva, so as to bar its progress. ”

“ Each egg, as it leaves the oviduct, is received by the hooks mentioned above, and by means of them it is rolled on the soil till a covering of earth adheres to the viscous material with which the egg is coated. The male considers the eggs special delicacies, and devours them whenever he has the opportunity. It is to prevent this that the female covers them with earth, so that the male may not recognize them.
Geophilus is a much longer animal than Lithobius, for its body may consist of from 80 to 180 rings. The species have no eyes. ”

“ When the mouth organs are removed, there will be no difficulty in taking out the stomach. This should be cut open with a needle, and then we shall see the gastric teeth (g g) which grind up the food against the fixed calcareous plate (b b) . The lower end of the stomach is set with fine hairs, which prevent the passage of food into the intestines until it has been ground fine between these living millstones. A similar arrangement is found in all the higher Crustacea. The time spent in comparing the gastric mill of the Crab with the ‘gizzard’ of the Cockroach will not be thrown away. ”

“ Sharp says that though the Earwig ‘is scarcely surpassed in numbers by any British insect, yet it is rarely seen on the wing. It is probable that the majority of individuals of this species may never make use of their organs of flight, or go through the complex process of folding and unfolding them.’
Let us choose our next example from the Leaping Orthop ́tera. They may be distinguished at a glance from their relatives that run, but do not [80] leap, by the peculiar structure of the third pair of legs. These are much longer and stouter than the other two pairs, and the thigh is very muscular. ”

“ Occasionally, however, they may be met with in daylight, leisurely stalking a smaller beetle or a fly; then with a dash seizing the victim in their powerful mandibles, which are quite capable of making an impression on the human skin, as those who handle these Beetles unwarily will discover for themselves. ”

“ The principles on which aquaria should be kept are now pretty generally understood. There should always be a small quantity of growing aquatic vegetation, and a supply of minute life to furnish food for the larger forms. Excess of light should be avoided, and the temperature should not be allowed to rise much above 50° F. Carnivorous beetles and their larvae may be fed with small pieces of meat, small garden worms, or tadpoles. ”

“ At any rate, the creature adopts the same plan as the larva of Chironomus, which has no gills at all, for driving away from its case water that has parted with its oxygen. Water charged with oxygen pours into the case, and so the air-supply is renewed. This plan is nothing more than keeping the fore-part of the body in undulating motion, the tail in both the larvae serving as a point of attachment. One or two that I have kept made their cases against the side of the bottle, and so afforded an excellent opportunity of seeing them in this motion. The Tanypus larva does the same thing. ”

“ The Common Garden Spider (Epei ́ra diade ́ma) is a very good subject, and there can be no difficulty in procuring any number of specimens. The smallest garden will be sure to yield a plentiful supply; and even if we have no garden, a very superficial search among the hedgerows will give us as many as we can possibly want. Every one knows this spider, and the beautifully regular web which it makes. First of all, what one may call the outline of the web is spun—strong threads stretching from [99] point to point, to which are attached lines radiating from a common centre. ”

“ Hill, who annotated the English edition of Swammerdam, says, ‘There is not perhaps in all the animal creation so outrageous or fierce a creature against those weaker than itself as the Water Scorpion. ”