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Super spiders

September 29, 2011

As autumn approaches and temperatures begin to drop, it is increasingly common to see spiders in our homes, where they occasionally seek refuge at this time of year. One of the largest, and therefore potentially alarming, is the fishing spider.

Dolomedes is a genus of spiders of the family Pisauridae. There are over a hundred species of Dolomedes throughout the world, with nine species in North America. Also known as raft spiders, dock spiders or wharf spiders, most are semi-aquatic.

They feed primarily on small insects and are opportunistic ambush hunters that typically feed at night to avoid their primary predators, which are birds. While most fishing spiders frequent waterways, the brownish-gray fishing spider depicted here is frequently found in woodlands at some distance from streams or ponds.

A chief characteristic of female fishing spiders is the construction of an egg sac, which is carried in the chelicerae (jaw-like or fang-bearing appendages), even when hunting. It is discarded when the spiderlings emerge.

Similar in appearance, wolf spiders are members of the family Lycosidae. Wolf spiders are generally large hairy spiders patterned with a mixture of black, gray and brown. An obvious difference is that they carry their egg sacs by attaching them to spinnerets at the rear of their bodies.

Both spiders play important roles in any ecosystem because they are numerous and are voracious insect predators.

Encountering spiders in our homes is not reason for panic. They can easily be relocated outdoors by gently placing a cup over the spider and carefully sliding a firm piece of thin cardboard under the cup’s opening.

Patient observation of any creature that we find frightening is an effective technique for overcoming such fear. To read a fascinating account of such an experience, see Mary Oliver’s essay, “Swoon,” in her collection “Winter Hours.”