Wild Side: Wolf spiders

They really do have eyes in the back of their head.

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The wolf spider. —Matt Pelikan

Among the most plentiful arthropods in very early spring are, perhaps surprisingly, spiders. Finding them takes some astuteness — most spiders active in early April are immature ones, and hence quite small. But, for example, on an outing to Correllus State Forest last weekend, I found four grasshoppers, two beetles, about a dozen flies, and well over 30 spiders of various kinds. In short, these eight-legged predators are quite dominant at this point in the season. Heaven knows, though, what they’re finding to eat.

Several families of spiders were among those I found last Sunday, but the most plentiful group — and the easiest group to find — were wolf spiders, in the family Lycosidae. This is a significant family, with about 240 species known in the U.S. And its members are among the most distinctive, conspicuous, and interesting of all spiders.

While a good bit of variation is evident among the Lycosidae, wolf spiders are generally fairly large (by spider standards) when mature; some of our species approach two inches across the span of their legs. Wolfies tend to be long-legged, robust, and fuzzy. And they have a distinctive eye arrangement: A row of four small eyes right above the jaws, a pair of larger “headlight” eyes pointing forward, and then a pair of slightly smaller eyes set farther back on the sides of the head. (Eye arrangement is a key thing to look at when it comes to spider identification, and a wolf spider’s complement of eight eyes is the typical number for spiders.)

As their name suggests, wolf spiders are capable predators, sometimes taking prey almost as large as themselves. They appear to me to be generalists, that is, taking whatever prey they encounter rather than specializing. Some hunt by day, others by night, but the methodology stays the same: A hunting wolf spider alternates brief periods of slow walking with longer periods of standing perfectly still. Their eye arrangement gives them nearly 360° vision, and their sight is acute and, in particular, sensitive to motion.

When another arthropod (even another wolf spider) wanders within range — wham! the hunter envelops its target in its legs and applies a venomous bite that quickly subdues the victim. As a rule, wolfies don’t spin webs, though they may leave a trail of silk behind them to advertise their presence to other members of their species.

Despite their violent dining habits, female wolf spiders are touchingly devoted mothers. Their eggs are laid into a silken bag that the adult female spins, and she drags this bag behind her until the eggs mature and hatch. At that point, the tiny youngsters pile on top of mom’s abdomen, where they ride for several days until they have grown enough to fend for themselves. A female wolfie with a crop of young’uns on her back is a charming sight, at least to a spider enthusiast.

Wolf spiders are ubiquitous on the Vineyard, though they are not enthusiastic climbers and are generally found on the ground. A few types seem to have very strong and sometimes surprising habitat preferences — one species, for example, appears to be restricted to cobble beaches, where it can be quite common. In general, though, wolfies seem highly mobile and adaptable, able to forage effectively under a wide range of conditions. They turn up regularly inside houses (if you find one, please just capture it in a jar and reintroduce it to the great outdoors).

Still very much a beginner with spiders, I don’t yet have a good sense of how many wolf spider species may live on the Vineyard. But I believe the number is fairly large, dozens at least, perhaps scores. Most species appear to overwinter at an immature stage (like many other arthropods, they grow to maturity through a series of molts, getting larger with each one). So at this point in the season, mostly what you find are half-grown individuals. But at least a few species either overwinter as adults or grow very quickly once they become active in the spring: By mid-April or so, adults start turning up, and by sometime in June, one starts seeing females carrying young or small wolfies that have just set out on their own.

While the name “wolf spider” seems calculated to make these arthropods appear threatening, in fact wolfies are docile animals that prefer to run and hide, rather than fight, when disturbed. Larger ones are capable of giving a painful bite — I’ve heard a wolfie bite described as feeling like a bee sting. But in my experience, these spiders can be handled gently without any problems. A good rule with any arthropod, if you want to handle it, is to encourage it to walk onto your hand, rather than grabbing it; as long as it’s unrestrained and not being squeezed, an arthropod of any kind is unlikely to bite.

Spiders are, admittedly, a tough sell: Many people have a strong, instinctive aversion to them. But they’re fascinating animals, well worth getting used to. And wolf spiders, a diverse, and may I say almost charismatic, group, are a good point of entry for learning more about spiders in general. Keep an eye out.