Monday, March 17, 2008

Monday Myth: Harvestmen

You'd be a rare duck indeed if you haven't, at least for a moment, found yourself falling for one of the common myths about arthropods. So in the tradition of Wordless Wednesday and Friday Beetle Blogging, I have decided to do "Monday Myth". I'll attempt weekly, and be happy if I manage bi. Inaugural myth for debunking: "Harvestmen are spiders". Just not true.
  1. Harvestmen aren't spiders
  2. They can't envenomate you
  3. The majority of species are scavengers or detritus feeders
  4. Their taxonomic (order) name: Opiliones. Harvestmen are sometimes confused with the Pholcidae family of spiders (a.k.a., "Cellar spiders").
Harvestmen are not spiders; however, Harvestmen are arachnids, so you can think of them as sort of a second cousin to spiders. Harvestmen are actually more closely related to another arachnid: scorpions and scorpion-like arthropods.

Harvestmen lack venom glands... They could not envenomate you if they wanted to. The majority of species are scavengers of detritus (decaying plant material), fungi, and dead arthropods or other animals. Very few species of Harvestmen are actually predatory, and even they must resort to ambush. Given their menu of choice, Harvestmen are web-less wanderers; they are often encountered on the ground or a wall searching for a meal, or hiding out in moist and protected environments (under eves, rocks, boards, even shadows of door frames, corners, etc.).

To quickly and easily differentiate between Harvestmen and spiders, look at the body... Note that as with (most) spiders, you can see two body sections: an abdomen (posterior section) and a cephalothorax (anterior section, which includes eyes, mouthparts, etc.). While Harvestmen technically have the same two sections, their body appears to be one contiguous oval rather than two distinct parts.

It's important to make these distinctions, because while Harvestmen are quite benign (to us), they are often mislabeled as something scary or threatening. So rest assured! If you find one, just put it outside...


Max said...


Thanks for visiting the Apartment Site. I will be checking in often on your blog since I have studied arthropods in the Southwest and I love to revisit the area however I can. I think the life stage figures are a great idea, but I am biased as well.

JP said...

Thanks for stopping by, Max, and for your comment/feedback. Hopefully there will be arthropods aplenty covered here as activity rises with the warmth.