Bob Dispenza, Director of Education, Allen County Parks, Fort Wayne, IN
They lie patiently in wait, their many eyes glittering. At the first opportunity, they pounce upon unsuspecting people, delivering death through fangs dripping with poison. All you have to do is see Shelob in “The Return of the King” to realize how many people view spiders. Just their names conjure up fear: Black Widow, Brown Recluse, Daddy-Long-Legs.
What? Daddy-Long-Legs? Yes, thanks to the Internet and urban legends, the humble daddy-long-legs has been promoted to the most “poisonous spider” in the world. Before we explore this further, let’s get our terms straight. Spiders can be venomous, but rarely poisonous. Venom is injected, poison is ingested. If you want to know if a spider is poisonous, you have to eat it. Daddy-long-legs are in the order Opiliones and are also called harvestmen. They live many places outside, and are recognized by their long, thin legs, undivided body with segments on the rear half, and lack of silk. There is also a true spider called daddy-long-legs, family Pholcidae, which frequents basements (and therefore is sometimes called the cellar spider). The way the story goes, daddy-long-legs are the most venomous “spiders”, but their short fangs don’t penetrate human skin, so they can’t hurt us. Stop and think about that for a minute – how would scientists find that out? They would have to extract venom and inject it into people to see if they die. Who’s going to pay for or support that research? As it is, harvestmen are mostly scavengers and not venomous at all, and no Pholcid spiders have been shown to be harmful.
For both of the following spiders, severity of a bite depends on immune reaction to the venom, quantity injected and bite location, along with the age and condition of the victim. As with any spider bite, collect the spider and seek medical attention. Both spiders are shy and will only bite as a last resort or in the process of being crushed, and both may be found in association with human dwellings.
Black widows (Latrodectus mactans) are quite rare over most of our region, and entirely absent from much of it, especially northward. Only mature females are venomous, and they are somewhat variable in appearance. In spite of their name, females only rarely eat males after mating. Usually black with a red hourglass shape on the underside, they can also be brown and have indefinite markings. I once shared a park entrance booth with some in North Dakota – they lived under the floorboards and kept to themselves. Their webs appear unorganized, without a definite form. Venom is neurotoxic, and is fatal less than 1% of the time. Symptoms include pain (especially in the back and abdomen), nausea, fever, tremors, breathing difficulties and elevated blood pressure.
Brown recluse (Loxosceles reclusa) spiders are also called violin or fiddleback spiders, referring to the violin-shaped marking on the cephalothorax. They have six eyes in 3 pairs, as opposed to the 8 eyes that many spiders have. At home in the lower Mississippi valley and southern Great Plains, the range of the brown recluse extends into the southern half of Indiana and southwest corner of Ohio, but they are rare even there. Occurrences outside this range are likely the result spiders of being moved accidentally by human activity. Brown recluse venom is hemotoxic, causing destruction of tissue and blood at the bite site, though there may be some systemic symptoms also. Fatalities are extremely rare. These spiders eat mostly dead insects found while roaming – the unorganized web is a daytime retreat. In areas where they are native, brown recluses may be quite common, almost communal in their habits. They may be found under beds or running through houses in Kansas, Missouri and Arkansas, where schoolchildern frequently collect them while looking for insects. People in these areas live in close association with brown recluses without dire consequences. Most necrotic lesions diagnosed as brown recluse bites are something else entirely, especially in our region, but many medical professionals are unaware of the spider’s range. I have never seen a live brown recluse, and the only dead one I’ve seen was caught in far southern Indiana. Wolf and nursery web spiders are often mistaken for brown recluses, and while they are large and dramatic, they are not dangerous.
Most spiders are venomous, but most are also harmless to people. They’re not the Gary Larson Far Side spiders, weaving a web at the bottom of a playground sliding board and telling each other “If we pull this off, we’ll eat like kings!” Their benefits in insect control far outweigh their negative aspects. Learn to love them – remember, you’re never more than three feet away from a spider.
Web resources:
Black widow (at Ohio State – Go Buckeyes!)
Brown recluse (Ohio State strikes again!)
Spiders - Great site dedicated to correcting spider misinformation (take the Brown Recluse Spider Challenge, and look for the Monty Python quotes!)
Arachnology web
