Dark fishing spider

Dark fishing spider is a large, robust, nursery web spider. It is the largest of all fishing spiders, the second largest spider in North America, and the largest spider in Minnesota.

The adult female body is ⅝″ to 1″ long. It is light brown with light and dark brownish-gray markings.

The front part of the body (cephalothorax) is about the same size as the rear part (abdomen). The covering (carapace) of the cephalothorax has dark markings that resemble the face of an ant. On the front on the cephalothorax there are eight eyes in two rows of four. Both rows of eyes are moderately curved. The inner eyes in the back row are only slightly larger than the outer eyes.

The abdomen is rounded in the front, widest in the middle, and tapers toward the rear. On the rear half of the abdomen there are three conspicuous, dark, W-shaped markings, each mark ending in a light brown mark. The W marks may be somewhat outlined in white but the outline will be broken and incomplete.

Each leg is conspicuously banded and has long black spines. The femur is light brown with black bands and the tibia are reddish-brown with black bands. The last leg segment (tarsus) has 3 claws. The legs are very long in proportion to the body size. The legspan of the female can be over 3″.

The male is similar to the female but only about half the size, ¼″ to ½″ long, and one-fourteenth the weight.

Male: ¼″ to ½″
Female: ⅝″ to 1″

Dark fishing spider does not produce a web to catch prey. The female produces a nursery web for its young.

Striped fishing spider (Dolomedes scriptus) is similar but smaller. The “W” markings on the rear of the abdomen are outlined in white all across the abdomen. The legs appear longitudinally striped, not horizontally banded.

Wolf spiders (family Lycosidae) have three rows of eyes, including a pair of very large posterior median eyes. The anterior median eyes are not visible from the front. Wolf spiders are most often seen perched horizontally.

Deciduous forests, often far from water; human houses near deciduous forests.

Early May through September

Dark fishing spider is most often seen perched vertically. It hunts for prey mostly at night, remaining motionless on a tree trunk, wall, or other vertical surface.

Dark fishing spider reproduces in mid-summer. A 2013 study shows that the male never survives the mating process. The male is monogamous, not out of loyalty, but because it spontaneously dies after mating while still attached to the female. The female then eats the dead male. In June the female produces a large egg sac into which she begins laying eggs. She carries the egg sac around with her mouth as she wanders about. The egg sac will eventually contain up to almost 1,400 eggs and be up to ⅝″ in diameter. When the eggs are about the hatch she attaches the sac to foliage well above the ground, builds a nursery web around it, and stands guard near it. The newly hatched spiderlings remain in the nursery web until they molt, and then they disperse.

Immature adults hibernate under stones, under loose bark, in tree cavities, and in human dwellings. Males mature and mate in the spring of the first year. Females mature in two years.

Large insects and small vertebrates