Scorpions are inhabitants of warm countries, and some tropical American species are six inches in length, but those of our Southern States are smaller. They have slender bodies consisting of a cephalothorax and a long abdomen ending in a sharp sting through which two poison glands inject poison into the wound made by it, the effect of which may be very severe on a man, and is fatal to the insects and other small creatures on which scorpions prey; this "tail" with the sting is usually carried curled up over the back. The body is protected by chitinous plates above and below. The legs are four. From the head spring two great, crablike, pincer claws. When these seize an insect they hand it back to two small but powerful appendages at their base which act as jaws. Between them is a small mouth. Scorpions are nocturnal in habit, hiding by day in crevices, and wandering about at night; thus they are likely to seek such dark retreats toward morning as a person's boots; and in hot, dry regions travelers must be cautious about examining their clothing and baggage to avoid being stung. The scorpions retain their eggs until hatched. The young when born differ little except in size from their parents, and are cared for with much solicitude by the mother, who carries them around with her for some time, hanging by their pincers to her body. The race is ancient, fossil remains occurring as early, at least, as the Carboniferous age.
The second order, Pseudoscorpionida, includes the "book scorpions," a series of minute, stingless, scorpion-shaped creatures found in moss, under the bark of trees, or more often on flies. A third order, Pedipalpida, is that of the scorpion spiders, or "whip scorpions" of the tropics; the fourth, Solpugida, contains certain ugly creatures intermediate between scorpions and spiders; and the fifth order, Phalangida, is that of the small-bodied, vastly long-legged things called "harvestmen" in England and daddy longlegs by us, which run about in the summer heat, and feed on minute insects. They abound in all the warmer parts of the world, and in great variety, South America showing some very bizarre forms. This brings us to the sixth order, Araneida—the spiders.
THE SPIDERS AND THEIR WEBS
Spiders are usually thought and spoken of as "insects" by the layman. Many persons call almost every creature an insect that is small and supposed to be useless, or suspected of harmfulness. But spiders are different from insects properly so called in many important particulars of structure and habits. Spiders have four pairs of legs, while insects have six legs. The spherical abdomen, which is cut off from the head by a deep constriction, shows no segmentation, and on its floor are large glands (the arachnidium) producing the silk which is exuded from three pairs of tubes with sievelike openings, at the end of the abdomen, called the spinnerets. Their nervous system is highly developed, and they show much intelligence. Spiders are of two sexes, but the male is usually much smaller than his mate.
When egg-laying time comes the female forms a little silken bed attached to grass, or underneath a stone, or stuck to some object, or placed in a burrow, or hung like a hammock by long guy lines, and deposits in it eggs like drops of jelly. One sort places this under water, forming a nest like an inverted cup and filling it with bubbles of air, and spending much of its time in this real diving bell. A common garden spider (Lycosa) forms globular cocoons, and drags them around attached to the spinnerets, regardless of jars and bumps. In a large section of the tribe this is all the use that is made of the silk, which differs from that of insects (caterpillars) in being made up of a great number of finer threads laid together while soft enough to unite into one.
It is a common habit with spiders to draw out a thread behind them as they walk, and in this way they make the great quantities of threads that sometimes cover a field of grass. This is the gossamer often so annoying to us in late summer, but a thing of beauty when glistening with dew.
The gossamer of autumn, however, is made by the very small spiders of the genus Erigones, which hide in the herbage, but in the fine weather that comes after the first frosts climb to the tops of posts, fences and tall weeds, in company with the young of larger kinds, and "turning their spinnerets upward allow threads to be drawn out by ascending currents of air, until sometimes the spiders are lifted off their feet and carried long distances." These are the "ballooning spiders" of which one hears. In this way the whole country is overspread with lines and tangles of trailing silken threads that whiten our clothes and stick to our faces.
Three or four hundred species of spiders might be obtained in almost any locality in this country by diligent search, and thousands of foreign species are known; hence only a few conspicuous examples may be mentioned here. The tribe may be divided according to habits into two groups of families: 1. The hunting spiders, which run on the ground or on plants, catching insects by chase or by strategy; and 2. The cobweb spiders, which make webs to catch insects, and live all the time in the web or in a nest near it.
In the former group are the Drassidæ, a family of small, varicolored spiders that run about on the ground or in bushes, one large genus of which (Clubiana) includes pale, or purely white species; their cocoons are baglike or tubular. The most conspicuous genus is Misumena, in which the species are white or brightly colored, and which spend their days among flowers, waiting in rigid attitude for an insect to alight near them on which they may pounce. Spiders can see well for four or five inches, but not much beyond that. The Attidæ are small, hairy, or scaly jumping spiders, often brightly colored, that are found in open places and on the tops of low plants, whence they leap on their prey, or make long jumps to escape danger. To the next family, Lycosidæ, belong the large spiders most often seen in fields and pastures. They are fond of dry, sandy places, where the females live in silk-lined holes. These lycosids are long-legged, rapid runners, and capture their game by running it down. To this family belongs the famous tarantula of southern Europe, fabled to produce a madness (tarantism) in a person bitten that could be cured only by dancing to music of a certain lively measure called "tarantella." (The so-called "tarantula" of our southwestern desert region, is, however, another species.) A common northern spider (Lycosa carolinensis) is its equal in size, (the longest legs covering a spread of three inches), and in color, black with gray legs. Still larger is another North American lycosid (Dolomedes tenebrosus), gray with spiny legs ringed with dark and light gray, which spreads four inches.
These big ugly creatures, and the bites of spiders generally, are regarded with unnecessary dread by most persons. The jaws (mandibles) are close together at the front of the head. They are two-jointed, the basal joint stout, and the end joint or claw slender and sharp-pointed. The claw has near its point a small hole, which is the outlet of the poison gland. "The poison kills or disables the insects which are captured by the spider. Its effect on the human skin varies in different persons. Sometimes it has no effect at all; oftener it causes some soreness and itching ... and cases have been known in which it caused serious inflammation which lasted a long time. Spiders seldom bite and only in self-defense, the bites so commonly charged to them being often the work of other animals."