The Dictynas are all small spiders, not more than a sixth of an inch in
length, but are brightly colored and live in webs in open places, where
they cannot fail to be seen by any one who looks for spiders. They are
not easily frightened, and so their habits can be more easily watched
than those of many larger kinds. The heads are high, arching up from the
eyes to the highest part opposite the first legs (fig. 476). The eyes
are higher and the front of the head is more nearly vertical than in
Amaurobius (fig. 489). The head is about half as wide as the thorax and
distinctly marked off from it and usually lighter colored. The abdomen
is sometimes marked with light yellow on a gray ground, as in
Amaurobius, or with a light middle stripe of various shapes, bordered
with brown or gray (fig. 487). The whole body is covered with fine
hairs, and there are often long white hairs in rows on the
cephalothorax. The cribellum is large for the size of the spiders and
can generally be plainly seen just in front of the other spinnerets. The
calamistrum is not so easy to see, but it covers about half the length
of the fourth metatarsus. The peculiarities of the species of these
spiders are more strongly marked in the males. The mandibles of both
sexes are long and a little curved forward at the ends (fig. 476), but
in the males they are sometimes so long that the distance from the ends
of the mandibles to the top of the head is as great as the length of the
cephalothorax, and the lower ends are turned forward at a sharp angle
with the upper part. The mandibles of the males are curved apart in the
middle, and they have at the base a short tooth projecting forward (fig.
477). The palpi of the males have a process on the tibia, usually near
the base, on the end of which are two spines (fig. 478). There is not
much difference in size between the sexes, but they are often very
differently colored, and the males do not have the cribellum and
calamistrum, or have only rudiments of them.
[Illustration: FIG. 472. Web of Dictyna in the corner of a window pane.]
[Illustration: FIG. 473. Web of Dictyna on the end of a twig.]
Some species live on walls and fences, making large webs that become
conspicuous from the dust which they collect. Others prefer the tops of
plants like stiff grass and the tops of golden-rod and spiræa. Others,
like _volupis_ (fig. 474), prefer leaves and the ends of growing
branches. The webs are usually irregular, but sometimes are nearly round
and formed by threads radiating from the spider's hole, crossed
irregularly by other threads (fig. 471).
[Illustration: FIGS. 474, 475, 476, 477, 478. Dictyna volupis.--474,
female. 475, male. Both enlarged eight times. 476, side of male. 477,
front of head of male enlarged sixteen times, showing curved mandibles.
478, palpus of male.]
$Dictyna volupis.$--This species and _frondea_ are brighter colored and
more slender than _muraria_ and _volucripes_ (fig. 484) and live among
the leaves of bushes. The female _volupis_ has the legs pale, almost
white, and the cephalothorax light brown, darker at the sides and light
on the head (fig. 474). The abdomen is yellow in the middle and brown,
sometimes red, at the sides. The middle yellow portion forms a regular
figure differing much in different individuals. The male is quite
differently colored. The cephalothorax, which is larger, is bright
orange brown, without much difference between the head and the sides
(fig. 475). The legs are light orange, darker than those of the female.
The abdomen is dark reddish brown, sometimes over the whole back, but
usually with a yellow irregular middle spot smaller than that of the
female. The ends of the male palpi are dark colored and as large as the
spider's head (fig. 475). The hairs are very fine and light colored and
do not modify the color as much as they do in the brown species. The
length of _volupis_ is not over an eighth of an inch. The abdomen is
oval and not as wide or high as in _volucripes_ and _muraria_. The head
of the male is high, and the mandibles almost as long as the
cephalothorax (fig. 476). The lower half is turned sharply forward and
flattened out at the end. The mandibles are light orange brown, so that
their shape is more readily seen than in the dark species. The tooth on
the front of the base of the mandibles is very large in this species
(fig. 477).
[Illustration: FIGS. 479, 480, 481. Dictyna frondea.--479, markings of
the abdomen enlarged eight times. 480, cephalothorax and palpus of male.
481, palpus of male.]
$Dictyna frondea.$--This resembles _volupis_ and is likely to be
mistaken for it. It is a little smaller, not over a tenth of an inch
long, and there is less difference between the sexes. The legs are pale,
and the cephalothorax light brown, lighter on the head. The abdomen is
gray at the sides, not as red as in _volupis_, and the middle light
stripe is narrower and not as bright yellow (fig. 479). The sternum and
under side of the abdomen are gray, as dark as the upper part and sides,
while in _volupis_ they are generally lighter. The males have the
cephalothorax larger, and that and the legs a little brighter colored
than in the female, and the abdomen darker. The mandibles are not as
long as in the male _volupis_, and the ends of the male palpi are much
smaller and the tibia longer and straighter than in _volupis_ (fig.
481).
[Illustration: FIGS. 482, 483. Dictyna cruciata.--482, female enlarged
eight times. 483, cephalothorax and palpi.]
$Dictyna cruciata.$--About a tenth of an inch long, with the abdomen
large and oval, as in _muraria_. The cephalothorax is light brown above
and below, and the legs the same color, but still lighter. The abdomen
is gray beneath and at the sides, and silvery white on the back,
sometimes over the whole upper surface, but oftener in a stripe widened
in the middle so as to form a white cross on a gray ground (fig. 482).
The males are darker colored, with the light spot on the abdomen
smaller. The male palpi are short and slender, the ends large and
rounded and carried close to the head (fig. 483).
[Illustration: FIGS. 484, 485, 486. Dictyna volucripes.--484, female
enlarged eight times. 485, tibia of male palpus of Dictyna volucripes.
486, tibia of male palpus of Dictyna muraria.]
[Illustration: FIG. 487. Varieties of marking on the abdomen of Dictyna
muraria.]
$Dictyna volucripes and muraria.$--These two gray spiders are the common
Dictynas on walls and fences and on the ends of grass and weeds, where
they make webs shaped according to the places where they live, having
in some part of the web a hole in which the spider usually hides (fig.
473). Some allied species make nearly circular webs on walls, with the
hole near the center, and gather so much dust as to appear like a spot
of dirt (fig. 471). _Volucripes_ is about a sixth of an inch in length,
and _muraria_ an eighth of an inch. _Volucripes_ is browner in color and
more common on plants, and _muraria_ is grayer and more common on
fences. Both species are marked much alike. The cephalothorax is dark
brown, partly covered with light gray hairs, some of which form roughly
three stripes on the head. The abdomen is large and round, in some
females nearly as wide as long. The front half has a middle dark spot of
various shapes, and the hinder half two rows of spots connected in pairs
with a middle line, forming a figure much like the markings of several
species of Epeira (figs. 484, 487). The legs are dark gray or brown,
covered with fine hairs, the first pair not much longer than the body.
In the females the mandibles are a little thickened in the middle. In
the male they are elongated and turned forward at the ends and curved
apart in the middle, and have a small tooth on the front near the base.
The palpi of the males (figs. 485, 486) are short, with the patella as
wide as it is long and wider than the femur and tibia. The tarsus is
half longer than wide and pointed at the end. In the tibia there is a
little difference between the species that can be seen by looking at the
palpi from the side; in _volucripes_ there is a stout process at the
base as long as the tibia itself and pointing upward at a right angle
with it (fig. 485); in _muraria_ the corresponding process is short and
turned forward, and the tibia seems proportionally longer (fig. 486).
The cribellum in both these species is large and can easily be seen in
front of the other spinnerets. The calamistrum extends over half the
length of the fourth metatarsus, which in _volucripes_ is slightly
curved.
[Illustration: FIG. 488. Web of Amaurobius sylvestris on a rough
conglomerate rock. The spider had a nest in a crack at one side.]
[Illustration: FIGS. 489, 490. Amaurobius sylvestris.--489, female
enlarged four times. 490, male palpus without the terminal joint to show
the processes of the tibia.]
$Amaurobius sylvestris.$--This is the common Amaurobius all over the
northern part of the country. It resembles our species of Tegenaria
(figs. 228, 233) and may easily be mistaken for them. It does not have
long upper spinnerets like Tegenaria, and the eyes are lower on the
front of the head. The females (fig. 489) are two-fifths of an inch
long, and the males a third of an inch, but with much longer legs. The
head of the female is almost as wide as the middle of the thorax, and
the eyes cover half its width. The front row of eyes are within their
diameter of the front of the head. The head is low in front and higher
halfway between the eyes and the dorsal groove. The mandibles are much
swelled at the base in front, as they are in _Tegenaria medicinalis_.
The abdomen is oval, widest behind, and usually as long as the
cephalothorax or longer. The legs are not more than a fourth longer than
the body, and slender for so large a spider. The cephalothorax is dark
brown, darkest in front, and the legs are a little lighter brown,
without markings. The abdomen is gray, with a double row of oblique
yellow or white markings on the hinder half and two curved marks of the
same color on the front. These spots sometimes run together, so that the
whole middle of the abdomen is light colored. The males have the head
narrower and the thorax wider and all the legs longer than the female,
and the cephalothorax and mandibles are not so dark colored. The male
palpi have the patella as short as wide, and the tibia very short and
wide, with a short hook on the outer and a longer and more slender one
on the inner side, as shown in fig. 490. The epigynum has a small middle
lobe inclosed by two lateral lobes that meet behind, and by this the
female can be distinguished from the next species,--_Amaurobius ferox_.
The cribellum (fig. 469) is sometimes covered by a fold of the skin, so
that it is not readily seen. The calamistrum (fig. 470) is a close row
of curved hairs on the upper side of the fourth metatarsus, about half
its length. In the male the cribellum is rudimentary, and there is no
calamistrum.
[Illustration: FIG. 491. Fresh part of the web of Amaurobius
sylvestris.]
This spider makes a large loose web under stones and sticks (fig. 488).
In the parts freshly made the loose bands of silk can be seen running
irregularly about on the other threads (fig. 491).
[Illustration: FIG. 492. Tibial joint of male Amaurobius ferox for
comparison with that of Amaurobius sylvestris (fig. 490).]
$Amaurobius ferox.$--This lives in houses and is probably an imported
species, as it is more common in Europe. It grows a little larger than
_sylvestris_ (fig. 489), and the head is a little more narrowed in front
of the legs. The colors and markings are much as in _sylvestris_, but
the abdomen is often darker, and the middle light stripe on the front
more distinct. The epigynum has a larger middle lobe, and the lateral
lobes are straighter and do not meet in the middle. The males are
colored like the females and have the thorax wider and the legs longer.
The palpi of the male have the tarsus short and round. The tibia (fig.
492) has only a small short hook on the inner side, and a large blunt
process on the outer side. The male palpi and the epigynum distinguish
these easily from the last species.
[Illustration: FIG. 493. Amaurobius americana, enlarged four times.]
[Illustration: FIG. 494. Female Uloborus plumipes, enlarged eight times,
showing the tuft of hairs on the front legs and the calamistrum on the
fourth legs.]
$Amaurobius (Titanœca) americana.$--Quarter of an inch long and deep
black, except the cephalothorax, which is dull orange color, but
covered, like the rest of the body, with long black hairs (fig. 493).
Some individuals have a few light gray spots in pairs on the abdomen.
The shape of the cephalothorax and abdomen are like _Amaurobius
sylvestris_, and the legs are of the same proportional length and
stouter. The palpi of the female have the tibia and tarsus a little
thickened. The metatarsus of the fourth legs has the calamistrum more
distinct than in others of the family, and the metatarsus appears
thicker up and down than it is sidewise. The male has the legs longer,
particularly the first pair, of which the tibia and metatarsus are more
elongated than the other joints, and have many small spines on the under
side. The male palpi have the tarsus large and round, supported by a
wide and very complicated tibia. It lives under stones in the hottest
and dryest places.
[Illustration: FIG. 495. Horizontal web of Uloborus near the ground, one
side attached to a fallen tree. The outer spiral is finished over only
half the diameter of the web. A line of loose silk runs across the web,
and in the middle is a peculiar zigzag spiral. The figure is about the
real size.]
[Illustration: FIG. 496. Web of young Uloborus in a raspberry bush. The
lower half of the web is much wider than the upper. A band of silk runs
across the middle and draws up with it some of the lower spirals. Half
the real size.]
$Uloborus plumipes.$--Uloborus makes a round web, like those of the
Epeiridæ, and when hanging in it resembles a Tetragnatha. The adult
female is about a quarter of an inch long, and narrow like Tetragnatha.
The cephalothorax is low in front and extends forward, in the middle,
beyond the mandibles, and the back part is widened and swelled up on
each side where the abdomen extends over it (fig. 494). The abdomen is
slightly notched in front and covers the cephalothorax a quarter of its
length. The abdomen is widest and thickest in the front third and has
there a pair of humps. The eyes are in two rows, those of the upper row
largest and on the top of the head, with the lateral pair farthest back.
The front row are on the edge of the head close to the mandibles. The
first pair of legs is the longest and is twice as long as the second. It
has at the end of the tibia a brush of long coarse hairs. The colors are
various shades of brown, from very light to almost black. The
cephalothorax has a light middle stripe. The legs have the joints light
in the middle and black at the ends, except the first leg, which
sometimes has the tarsus and metatarsus white, and the rest of the leg
dark brown. The fourth metatarsus is curved in on the outer side, where
the calamistrum is placed. The male is smaller than the female, the legs
are longer, the abdomen is smaller and less distinctly humped, the first
legs do not have the brushes on the tibia, and the fourth legs do not
have the calamistrum. The webs resemble those of Epeira and Tetragnatha,
and are horizontal or inclined. They are often left unfinished, with
several turns of the wide temporary spiral still in them (fig. 495).
Sometimes there are zigzag lines of loose silk across the center or in a
middle spiral, and when the eggs are laid the long cocoons are fastened
in a line of silk across the web (fig. 497). When this is done the
center of the radii of the web is usually at the upper part, instead of
in the middle, and the whole web is one-sided. It is found all over the
country, usually in shady woods, in bushes, or in the lower branches of
trees, especially in the lower dead branches of pines.
[Illustration: FIG. 497. Web of old Uloborus. The spider is in the
middle and at the left are three egg cocoons. One-third the real size.]
[Illustration: FIG. 498, 499. Hyptiotes cavatus.--498, female enlarged
eight times. 499, end of hind leg, showing calamistrum.]
$Hyptiotes cavatus.$--This peculiar spider resembles in shape and color
the end of one of the dead pine branches among which it lives. It is a
sixth of an inch long. The cephalothorax is as wide as long, highest in
the middle, and hollowed behind under the abdomen. The abdomen is oval,
thickest behind, and flattened in front, and has on the back four pairs
of slight elevations, on which are a few stiff hairs (fig. 498). The
legs are short and thickest in the middle, tapering toward the claws.
The hind metatarsi are curved in at the calamistrum (fig. 499). The eyes
are arranged as in Uloborus, but are farther apart and farther back on
the cephalothorax. The male is half as large as the female, the abdomen
smaller, and the humps lower.
[Illustration: FIG. 500. Webs of Hyptiotes in the top of a bush. Half
the real size.]
The web (fig. 500) consists of four rays crossed by a dozen or more
threads. The point where the rays meet is attached to a thread which
extends to the spider's roost, usually the end of a twig. Here it holds
on by the hind feet and draws the thread tight with the fore feet. When
an insect strikes the web the spider lets go with the hind feet and is
jerked forward by the contraction of the web, and slides along toward
its center, where it finds the prey and takes it out of the web to its
perch. The making of this web has been described by Wilder in the
_Popular Science Monthly_ in 1875. The cross threads are made
separately, beginning with the longest. They are begun on the upper ray,
the spider walking toward the center, combing out the threads with its
hind legs, until it reaches a point where it can cross to the next. It
is found all over the country, usually in the pine woods.
[Illustration: FIG. 501. Filistata hibernalis, enlarged twice.]
$Filistata hibernalis.$--One of the most common house spiders in the
southern states, making webs in corners and on walls and fences (fig.
501). The body is about half an inch long, but the legs are so long and
stout that it appears much larger. The first leg, which is the longest,
is about twice the length of the body. The palpi are as long as the
cephalothorax and thicker than in most spiders. The maxillæ are inclined
toward each other so that they meet in front of the labium. The
cephalothorax is flat and narrowed in front between the palpi, and the
mandibles are small. The eyes are in one group, close together. The
color is dark gray, without any markings, and the whole body is covered
with fine short hairs. The calamistrum is very short, and near the base
of the fourth metatarsus, where it can easily be seen. The web is like
that of Dictyna, radiating irregularly from the spider's hiding place,
and when this is on a flat wall forms sometimes a circle a foot or more
in diameter, which becomes filled with dust and is enlarged and
thickened as the spider grows.