The spiders that cause probably more agonistic language on Bonnie’s part around our house than any other arachnid or bug are the nursery web spiders.

I keep telling her their name should actually endear them to her because her No. 1 criterion for evaluating the moral character of everything from bacteria to presidents is how they treat their kids. Nursery web spiders get their name from the fact that for a while the female carries her egg sac around, then builds a silk web where the eggs hatch, and guards the spiderlings for a week or so after they’re born. Anthropomorphically speaking, it’s kind of lovable.

The trouble is, among the 680 or so spider species known to live in Maine, the nursery web spiders are — not to put too fine a point on it — big. Front leg tip to rear leg tip extended can span upwards of an inch, which looks like a monster to an unsuspecting dishwasher who’s suddenly face to face with one on a window screen. They’re hunters, so they roam around brush and sometimes the porch or other startling spots like the kitchen counter, looking for fat arthropods.

Our common species of nursery web spider, Pisaurina mira, practices a remarkable courtship and mating process, and its cousin in Europe, Pisaura mirabilis, has a unique approach that ours, by all accounts, does not share.

In North America, the male P. mira spider wanders around until he detects the silk dragline of a female. He then follows the silk, pausing cautiously for short periods and raising one of his front legs. As long as she keeps watching, he slowly approaches, and the pauses become longer. At some point the female might decide she doesn’t like him, and she runs off to some inaccessible spot.

If she decides she likes him, though, she allows him close enough to gently touch her hind legs with his front legs. After some leg interplay, she scoots to an apparently predetermined mating spot and attaches a dragline. He quickly follows her and takes up a position behind and over her. She then dangles freely on the dragline. He follows, and using his palps — the little handlike appendages spiders have beside their mouths — carefully turns her over. While he’s doing this, he folds her legs in and binds them with a “veil of silk,” as the researchers put it.

Cradling her in his legs, he then positions himself so he can reach around her body with his palps, where sperm is stored. With his left palp, he gently places sperm into her epigynum opening. He then repositions and repeats the insertion with his right palp.

This happens a few times until the female gets restless. He then releases her, just adding a little more binding to the veil and retreating to a safe distance. The female, still dangling, frees herself from the silken bonds. Soon she’ll be carrying around an egg sac in her palps and jaws (called chelicerae).

Very few spider species are known to bind the female with silk during copulation, but it’s an at least superficially understandable practice because in many spiders, the female is apt to eat the male at some point before, during or after sex. It doesn’t happen very often in most spiders, but sometimes. So the male’s binding practice is at least partly insurance against being attacked and consumed.

The European cousin takes a different approach to the affair. P. mirabilis is the only spider species known in which the male courts the female with an offering of food.

The male, which as in most spiders is smaller than the female, usually first catches a bug, such as a fly, and usually wraps it in silk. (Giftless males in studies were by far less successful in mating than gift-bearing males.) He then locates the dragline of a female who might be willing and carefully approaches her, holding the nuptial gift (technical phrase) in his chelicerae. If the female decides to receive him, she moves slowly toward him. He then raises the gift in his palps and leans backward. At some point, the female grabs the gift.

Occasionally she makes off with it without copulating, but usually the male maintains a grip on the gift with his legs and a line of silk. He positions himself over her back, and while she’s eating, he commences the reach-around copulation with his palps. The longer copulation lasts, the more sperm can be transferred.

Sometimes the female interrupts the copulation. When this happens, the whole session might end with the male making a hasty retreat. He might also play dead, which the arachnologists call “thanatosis.” It’s probably a strategy to prolong copulation as well as to avoid being eaten, though it’s not known for sure.

Among nursery web spiders, sexual cannibalism, as it’s called, happens only about 2 to 4 percent of the time and almost always before copulation, which accounts at least partly for the males’ gingerly approach. But it’s been known to happen afterward, and researchers observed one nursery web male eaten during copulation. He had brought no gift.

Why female spiders eat the males sometimes, the scientists aren’t sure. There is some kind of awareness in little arachnid minds that enables them to choose between potential mates. But why they can be overcome by a desire to eat a mate, no one really knows.

I’m not sure how cannibalism practices play in Bonnie’s existentialist philosophy of arachnid life. When I told her about all this, she just swore and said, “Of course they do that. They’re spiders.”

I think I’m in love.

Dana Wilde lives in Troy. He is a contributor to “Pluto: New Horizons for a Lost Horizon” available from North Atlantic Books. You can contact him at [email protected] Backyard Naturalist appears the second and fourth Thursdays each month.


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