The Tetragnathas are slender, usually straw-colored spiders, living in
their webs among the long grass in meadows and near water. The legs are
slender, the cephalothorax narrow, and the abdomen long and cylindrical.
The mandibles are large in both sexes, and in the males are very long
and furnished with long teeth at the end and along the inner margin.
When pairing, the male and female hold each other by the ends of the
mandibles. The eyes are in two rows nearly equal and parallel, and the
distance between the lateral pairs varies in different species. The
palpi are long and slender in both sexes, and in the males their
proportions differ according to the species. The legs are also long and
slender, and vary in length from _grallator_, where the female has the
first legs ten times as long as the cephalothorax, to _laboriosa_, in
which they are seven times as long. The webs are generally inclined and
may be nearly horizontal or nearly vertical, according to the place
where they are made (fig. 459). The inner spiral is small and has a hole
in the middle (fig. 460). The spider stands in the web with the legs
extended forward and backward close to each other, except at the ends,
where they are turned outward (fig. 459). On account of their similar
size and color, the species look at first sight much alike, but there
are differences in the arrangement of the lateral eyes and the length of
the legs, palpi, and mandibles.
$Tetragnatha grallator.$--This spider grows to be half an inch long,
with the first legs an inch and a half. The mandibles of the female are
as long as the cephalothorax, and those of the male longer (figs. 461,
465). In both sexes they are inclined forward, so as to be nearly
horizontal and spread apart at the ends. The lateral eyes are near
together, so that they almost touch, and the upper row when seen from
above is nearly straight. The palpi of both sexes are over one and a
half times as long as the cephalothorax, and in the males sometimes
twice as long (fig. 465). The patella and tibia together are nearly as
long as the femur. The color is sometimes light yellow, but often gray,
with a broken middle stripe of darker gray on the abdomen, and three
stripes on the cephalothorax. The abdomen is generally enlarged a little
in the front third (fig. 461). The males are smaller and more slender
than the females, with longer legs and mandibles.
[Illustration: FIG. 459. Web of Tetragnatha in tansy plants, showing the
spider in its usual position.]
$Tetragnatha extensa.$--Female a quarter to three-eighths of an inch
long, with the first leg three-quarters of an inch. The abdomen is
shorter than in _grallator_, about twice as long as the cephalothorax,
and not as much widened in front (fig. 462). The mandibles are
two-thirds as long as the cephalothorax and not much inclined forward.
The lateral eyes are near together. The colors are often dark, dull
yellow brown or gray, with three lines on the cephalothorax and a
middle dark stripe on the abdomen, with a light silvery stripe on each
side.
The male is smaller and more slender, with the legs longer. The male
palpi are one-half longer than the cephalothorax, the femur forming
nearly half its length (fig. 466).
[Illustration: FIG. 460. The same web shown in Fig. 459, treated so as
to show the inner spiral and the hole in the middle of the web.]
$Tetragnatha laboriosa.$--A little smaller than _extensa_, with shorter
legs and mandibles, the latter short enough in the female to be almost
vertical (fig. 463). The abdomen is proportionally longer than in
_extensa_, usually in the females three times as long as the
cephalothorax. The first legs are about seven times as long as the
cephalothorax. The upper row of eyes is a little curved, so that the
lateral pairs of eyes are as far apart as the middle ones (fig. 467).
The general color is light yellow. The abdomen is silvery white, with
some indistinct gray markings along the middle, and dark stripes on the
under side. In the males the mandibles (fig. 467) are short compared
with the other species, and are about two-thirds as long as the
cephalothorax, and the tibia is very little longer than the patella.
[Illustration: FIGS. 461, 462, 463, 464. Backs of females of four
species of Tetragnatha.--461, grallator. 462, extensa. 463, laboriosa.
464, straminea.]
[Illustration: FIGS. 465, 466. Cephalothorax, mandible, and palpus of
males.--465, Tetragnatha grallator. 466, Tetragnatha extensa.]
[Illustration: FIGS. 467, 468. Cephalothorax, mandibles, and palpus of
male.--467, Tetragnatha laboriosa. 468, Tetragnatha straminea.]
$Tetragnatha straminea.$--A quarter to three-eighths of an inch long,
about the same size as _laboriosa_, and the same color. The legs, palpi,
and mandibles are all a little longer than in _laboriosa_, and the
lateral eyes are farther apart than the middle pairs (fig. 464). In the
males the abdomen is shorter and smaller, and the legs longer. The male
palpi (fig. 468) are one and a half times the length of the
cephalothorax. In females the abdomen is usually three times as long as
the cephalothorax and more slender than in _laboriosa_.