The Common Spiders of the United States

J. H. Emerton

The Common Spiders of the United States

Published by Good Press, 2022

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EAN 4064066218614

Table of Contents

PREFACE

INTRODUCTION

THE DRASSIDÆ

THE GENUS CLUBIONA

THE DYSDERIDÆ

THE THOMISIDÆ

THE GENUS MISUMENA

THE GENUS XYSTICUS

THE GENUS PHILODROMUS

THE ATTIDÆ

THE LYCOSIDÆ

THE GENUS LYCOSA

THE GENUS PARDOSA

THE AGALENIDÆ

THE THERIDIDÆ

THE GENUS THERIDIUM

THE GENUS STEATODA

THE LINYPHIADÆ

THE GENUS LINYPHIA

THE GENUS ERIGONE

THE EPEIRIDÆ

THE THREE SPECIES OF THE GENUS ZILLA

THE GENUS ACROSOMA

THE GENUS TETRAGNATHA

THE CINIFLONIDÆ, OR CRIBELLATA

THE GENUS DICTYNA

INDEX

PREFACE

Table of Contents

There are few books on the American spiders, and these are either large and expensive works or else special papers published by scientific societies, and so little known to the public. Since publishing my papers on the New England and Canadian spiders in the Transactions of the Connecticut Academy from 1882 to 1894, I have had frequent calls for a smaller and simpler book to meet the wants of readers who, without making a special study of the subject, want to know a little about spiders in general and especially those species that they often meet with. It is hoped this book will answer the purpose and help to lessen the prejudice against spiders, and lead to a more general acquaintance with them, like the popular knowledge of birds and butterflies. The characters used in the descriptions are, as far as possible, those that can be seen without microscopic examination and without much experience in the handling of small animals. The illustrations, which show the form and markings of every species, are from my own drawings and photographs, a large part of them made new for this book.

J. H. EMERTON.

April, 1902.

INTRODUCTION

Table of Contents

This book is designed to make the reader acquainted with the common spiders most likely to be found over a large part of the United States as far south as Georgia and as far west as the Rocky Mountains. Local collections show that in the neighborhood of any city in the country there are at least three or four hundred species of spiders; but few such collections have been made, and it is not yet possible to tell all the kinds of spiders that live in any particular place, or how far any species extends over the country. The species which are here described and figured are all of them well known and have been described in other books. Rare and doubtful species are omitted, though some of these may in time prove to be among the most common. A large number of spiders are too small to be easily seen, and most of these are omitted, only a few representative species being described. Spiders have, unfortunately, no common names, except such indefinite ones as the garden spider, the black spider, the jumping spider, and the like. Even tarantula has become only a nickname for any large spider. The names of spiders, like those of other animals, have been given to them independently by different persons, so that many of them have more than one name, and the more common the spider the larger the number of names. In this book only one name is usually given to each species, and the name used is one that has been published with a description of the species in some other well-known book. Readers who are interested in the names of species and in comparing the classifications of different naturalists are referred to a Catalogue of the Described Araneæ Of Temperate North America, by George Marx, in the Proceedings of the United States National Museum, 1890, which is a useful index to what has been published on American spiders.

The front half of a spider's body, called the cephalothorax, contains in one piece the head and thorax, the only outward division between them being shallow grooves from the middle of the back to the front legs. In the middle of the cephalothorax is usually a groove or depression, under which, inside, is a muscle that moves the sucking apparatus by which food is drawn into the mouth. At the sides of the thoracic part are four pairs of legs, and on the head part are a pair of palpi and a pair of mandibles. The legs have seven joints: (1) the coxa, the thick basal joint, having little motion; (2) the trochanter, a short joint moving very freely on the end of the coxa; (3) the femur, the largest joint of the leg, moving with the trochanter in all directions; (4) the patella, moving up and down on the end of the femur; (5) the tibia, joined closely to the patella and moving with it up and down; (6) the metatarsus; and (7) the tarsus, moving together on the end of the tibia. The palpi are like small legs and have one less joint than the walking legs. The mandibles are close together at the front of the head (fig. 2). 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 like the stings of mosquitoes and bees, and cases have been known in which it caused serious inflammation which lasted a long time. Spiders seldom bite, and only in defense, the bites so commonly charged to them being often the work of other animals.

Fig. 1.

Diagram of the under side of a spider, with the legs removed except one.

Fig. 2.

Front of head, showing the eyes and mandibles.

On the front of the head are the eyes, usually eight in number, differing in size and arrangement according to the kind of spider. The sight of spiders is distinct for only short distances. Spiders of middle size can see each other, and the insects which they eat, at a distance of four or five inches, but beyond that do not seem to see anything clearly. At the ends of the feet are two claws, curved and with teeth along the inner edge, and in many spiders there is a third shorter claw between them (fig. 212). The claws are sometimes surrounded by a brush of flattened hairs (figs. 104, 114). The basal joints of the palpi are flattened and have their inner edges extended forward so that they can be used as jaws to press or chew the food. These are called the maxillæ. Between the maxillæ is a small piece called the labium, and between the legs is a larger oval piece called the sternum.

The hinder half of the body, the abdomen, is connected with the cephalothorax by a narrow stem (fig. 1). It has at the hinder end the spinnerets, three pairs of appendages having at their ends a great number of microscopic tubes through which the thread is drawn out. When not in use the spinnerets are folded together, so that the smaller inner pair are concealed.

The thread of spiders resembles that spun by caterpillars in making their cocoons, and can be manufactured in the same way into silk cloth. The spider's thread is composed of a great number of finer threads passing from the body through separate tubes and uniting into one before they have time to dry. This can be seen by examining the attachments of spiders' threads to glass. All the spinning tubes are not alike, but on certain parts of the spinnerets are larger or differently shaped tubes, and these are the outlets of glands of different kinds in the spider's abdomen, and are used in making different kinds of threads for certain parts of the webs, nests, or cocoons.

In front of the spinnerets on the under side is a small opening to the tracheæ, or air-tubes (fig. 1). At the front of the abdomen on the under side is a transverse fold of the skin, at the ends of which are the openings of the air-sacs or lungs, and between them the opening of the reproductive organs (fig. 1). The latter is covered in females by an apparatus, sometimes large and complicated, called the epigynum. Its presence shows that the female is full grown. Young spiders do not have it. Male spiders have the ends of the palpi enlarged, and under the terminal joint what is known as the palpal organ, sometimes very complicated in shape. The presence of these organs shows that the male is full grown. Young males that have nearly reached maturity have the ends of the palpi simply enlarged. Male spiders almost always have the body smaller and the legs longer than females of the same species.

The colors of spiders are partly in the skin itself and partly in the hairs and scales that cover it. Almost all spiders are covered with hair of some kind, but in some species it is so fine and short that it has little effect on the color. In others the skin is entirely covered with hairs of various lengths and sometimes with scales somewhat like those of butterflies, flattened and feathered or toothed on the edges. The colors of spiders are very varied, and in many species, especially of the jumping spiders, as brilliant as those of butterflies. The most common colors are grays and browns, resembling the ground or plants and stones among which the spiders live. Sometimes the color is uniform all over the body, except that it is a little darker toward the head and the ends of the feet. The most common marking is a spot on the front of the abdomen over the spider's heart, sometimes merely a translucent part of the skin and sometimes a definite color spot darker in the middle and outlined with a lighter shade or white. The hinder half of the abdomen is often marked with several pairs of spots, becoming smaller toward the end, and these spots may be united into a pair of stripes or a more complicated pattern. (See figures.) The legs are often marked with rings of color, almost always at the ends of the joints. Besides these common markings there are in some spiders strong contrasts of color, such as bright red or yellow spots on a black ground. In the males, especially among the Attidæ, there are often shining scales that reflect different colors in a bright light, and tufts of black or white hairs about the head and front legs.

Spiders live in all kinds of places. Certain species are attached to houses and seldom found far from them, and many of these occur over a large part of the world. The light webs in the corners of rooms are chiefly the work of Theridium tepidariorum (p. 112), occasionally of Steatoda borealis (p. 119) and Steatoda triangulosa (p. 121). In cellars the thin webs about the stairs and shelves are those of the long-legged Pholcus phalangioides (p. 129) or of Linyphia nebulosa or minuta (pp. 144, 145), and the thick flat webs in corners and between the beams are those of Tegenaria derhamii (p. 96). On the outside of houses live two jumping spiders, the most common being Epiblemum scenicum (p. 60), a small gray species the color of weathered wood, and the other, Marptusa familiaris (p. 61). Some of the round-web spiders live in great numbers about houses. The three brown species, Epeira sclopetaria (p. 160), patagiata, and strix, hide in cracks and at night make their round webs in porches, barns, and bridges. In the northern part of the country Epeira cinerea (p. 165) has the same habit. Epeira globosa (p. 174) is often found on the outside of houses, and so are Zilla atrica and Zilla x-notata (p. 185). Amaurobius ferox (p. 215), a large imported species, is sometimes found in cellars, and several Dictyna (p. 206) live in great numbers on the outside of houses, in corners of windows, under the edges of shingles, or in cracks of walls, spreading their webs wherever there is room for them and gathering dust so that they often make a distinct spot on the wall. In the southern states Filistata hibernalis (p. 220) is one of the most common spiders about houses. Its webs often make a round spot of dust a foot or more in diameter. Stones and sticks lying on the ground furnish shelter for a great number of spiders. Steatoda borealis (p. 119), marmorata (p. 121), and guttata (p. 120) and Asagena americana (p. 122) are found in such places, and so, especially in the South, is Latrodectus mactans (p. 122). The large jumping spiders, Phidippus mystaceus (p. 50) and tripunctatus (p. 51), make large nests of white silk under stones near the ground. The ground spiders, Drassus saccatus (p. 6), Gnaphosa conspersa (p. 2), and Prosthesima atra (p. 5), run on the ground and hide under stones. Lycosa nidicola (p. 69), Lycosa communis (p. 75), Lycosa pratensis (p. 69), polita (p. 70), and cinerea (p. 74) are often found under shelters of this kind. The crab spiders of the genus Xysticus live under stones, but oftener under bark farther from the ground.

In the summer, plants of all kinds from grass to trees are full of spiders. The Lycosas (pp. 68 to 84)run among the short grass. The small species of Linyphia (p. 134) and Erigone (p. 148) make their flat webs close to the ground among small plants. Linyphia marginata, communis, coccinea, and phrygiana make theirs among plants and rocks, a foot or two above the ground. The Theridiums (p. 110) live between leaves and on the ends of twigs, covering them with webs that only show when the dew is on them. Agalena nævia (pp. 91 to 95) makes its flat webs on the grass and anywhere else where it can find a place to fasten them. The jumping spiders (p. 41) run about for their prey on plants, and some of them have silk nests among the leaves. The Misumenas (p. 25) live among flowers and wait for insects to alight within reach. The webs of Dictyna (p. 206) are commonest on the ends of grass and twigs, and are known by the dust that they gather. The round-web spiders mature in the middle of the summer, and then Epeira trivittata (p. 166) is found on all kinds of bushes and grass, and later Epeira insularis (p. 169) and Epeira trifolium (p. 171) in hidden nests near their webs. Epeira angulata, sylvatica, and nordmanni (p. 162) live among bushes and trees. Cyclosa conica (p. 183), Acrosoma spinea (p. 190), and Uloborus (p. 216) live among low bushes in openings of the woods. Hyptiotes (p. 218) lives among the lower dead branches of pines, perching on the end of a twig which it exactly matches in color.

The marshes are the home of great numbers of spiders. The Tetragnathas (p. 198) live there, especially along the streams and ditches. Epeira gibberosa (p. 175) and placida (p. 176) make their horizontal and oblique webs among the tall grass in open places. The two species of Argiope (pp. 193 to 198) swarm in marshes and open fields and in autumn become conspicuous by their size and bright colors, and when they disappear leave over winter their brown cocoons (pp. 197, 200) fastened to the grass.

The moss and dead leaves in the woods are alive with spiders; even in summer some species always live there, and in winter the young of those that in warm weather live among the bushes find shelter where they can remain torpid through the cold season without freezing.

The eggs of spiders are covered with silk, forming a cocoon which varies much in shape and color in different species. Some spiders hang it in the web, others attach it to plants or stones, and others carry it about with them either in the mandibles or attached behind to the spinnerets. The young remain in the cocoon until they are able to run about, and after coming out of the cocoon keep together for a short time, sometimes in a web which they make in common, sometimes in a nest made by the mother, and in some species on the mother's back, but they soon scatter and hunt their own food or make cobwebs, according to the habits of the species.

Different kinds of spiders mature and breed at different times of the year, most of them living only one season. Those that mature late, like Agalena nævia and Argiope, pass the winter as eggs, while those that mature early, like Epeira sclopetaria and Lycosa nidicola, pass the winter half grown. Some species, like Theridium tepidariorum (p. 112), breed several times in the year, and old and young are found at all seasons.

The spiders are naturally divided into two groups of families: (1) the hunting spiders, which run on the ground or on plants, catching insects wherever they find them, or waiting among leaves and flowers until insects come within their reach; (2) the cobweb