The Common Spiders of the United States

by J. H. Emerton

THE GENUS MISUMENA

The Misumenas are the most conspicuous spiders of their family, and are among the few that are popularly noticed. They grow to a large size and are white or brightly colored, and live in open places on flowers. The males and females differ widely. The males mature early and remain small, and are marked with a variety of colors in spots and bands, while the females grow several times as large, lose in great part their markings, and become white or yellow. In both sexes the two front pairs of legs are much longer than the two hinder pairs, and often differently colored. In the young the colors are variable and there is less difference between the sexes. The Misumenas live on plants, among the flowers, especially on large flat clusters, like those of carrot and thoroughwort. They stand among the flowers, holding by the hind legs, with the front legs extended or bent in stiff and awkward positions, and wait for insects to alight on the flowers within their reach. Whether spiders prefer flowers colored like themselves is an unsettled question; at any rate, Misumenas of all colors and both sexes have been found on white flowers. Occasionally individuals are found on flowers of exactly the same color as themselves; for example, deep yellow M. aleatoria on the wild indigo, Baptisia tinctoria, and the reddish M. asperata on the flowers of sorrel, Rumex acetosella. The adult females of vatia and aleatoria are easily mistaken for each other. Both vary in color from white to deep yellow, and grow to a large size, but they can be distinguished by the difference in the shape of the head. Asperata is perhaps the most common species. The female seldom grows as large as the others, and does not lose entirely the red markings of the abdomen and legs. The scattered stiff hairs also distinguish it from the others. The males of the different species are distinct enough one from the other, though they differ widely from the females. The shape of the head and the markings around the eyes are much the same in both sexes, and by these males and females of the same species may be recognized.

Misumena vatia is the largest species and lives all over this country and Europe. It is sometimes half an inch long, and the first legs spread an inch and a half [(fig. 77)]. It is white, with sometimes a crimson spot on each side of the abdomen and another on the front of the head between the upper eyes. The sides of the thorax are a little darkened with yellow or brown, which extends around the head to a distinct opaque white spot under and between the eyes [(fig. 76)]. This white spot widens below over the mandibles and above under the eyes and around the eyes of the upper row. The shape of this mark and the greater height of the head distinguish this species from aleatoria (figs. [79, 80]). On the back of the thorax is also a distinct opaque white spot. The first and second legs have usually a light brown mark on the upper side, but this is sometimes absent.

The male [(fig. 78)] is only a quarter or a third as long as the adult female. The front legs are proportionally longer than in the female, and the abdomen smaller and more pointed behind. The males are strongly marked with reddish brown on a light ground. The thorax is dark at the sides, while the front of the head is white like that of the female.

Misumena aleatoria.—The female of this species grows nearly as large as vatia, and in some places is much more common. It is white or yellow, but does not have the crimson markings at the sides of the abdomen or between the eyes. The head [(fig. 79)] is rounder than in vatia and much lower in front, and there is a narrow white stripe under the eyes that divides at the sides, one branch passing around over the mandibles and the other close under the eyes. The sides of the cephalothorax are gray or green. The abdomen usually has no markings except a little gray color in the middle, but sometimes it has two rows of dark brown spots [(fig. 81)], and in such individuals the legs are also marked with brown at the ends of the joints. The males are very small and strikingly colored [(fig. 82)]. The two front pairs of legs are brown, the cephalothorax green, and the abdomen yellow. The shape of the head and the white under the eyes are the same as in the female.

Misumena asperata.—The males and females of this spider are more alike than in vatia and aleatoria. The adult females are always pale and sometimes white, but seldom lose entirely the reddish bands around the legs. Both sexes are covered with short stiff hairs about their length apart all over the upper part of the body and legs. The usual color is pale yellow, with dull red markings. The thorax is reddish at the sides. The abdomen has two red bands or rows of spots on the hinder half, meeting behind. In front are a middle pair of spots and two side bands that spread apart in the middle and meet again at the spinnerets. The tibia and tarsus of the front legs are marked with a narrow red ring at the base and a wider ring near the end of each joint. The female is a quarter of an inch long and the male about half that length. The markings of the male are like those of the female, but the spots are larger and more deeply colored. The male palpi are larger than in the other species.

The male M. spinosa of Georgia resembles asperata, but the legs are much longer and the ends of the palpi smaller.

Synema parvula.—A common species in the South. Length about one-eighth of an inch. The thorax is as wide as long, round and high in the middle. The abdomen is as wide as long, widest across the middle, and a little pointed behind. The third and fourth legs are not more than two-thirds as long as the first and second, and lighter colored. The thorax is orange-colored, a little darker at the sides, and with a dark brown line on the edges over the legs. There are light rings around the eyes. The abdomen is white or light yellow in front, and has a wide black or brown band across the hinder half, not reaching back to the spinnerets, and sometimes partly divided by a notch in front. On the front half of the abdomen are some small dark spots and usually several opaque white marks. On the under side of the abdomen there is a dark band on each side extending back to and partly surrounding the spinnerets. The front legs are orange brown, with the femora darker on the front and rear edges. The other joints are a little darker at the ends. The males are a little smaller and darker in color, but differ little from the females.