Ask The Entomologist

Harvestmen, or Daddy-Long-Legs

Earlier this week, I met a Harvestman while making supper. It had stowed away on some kale from the garden, and was still walking about on it… even after a week or so in the refrigerator.

The refrigerated Harvestman was promptly photographed and released in our garden’s cold frames.

Harvestmen have a rather well-known urban legend. Perhaps you’ve heard people say that “they’re the most venomous spiders in the world, but are harmless to humans because their fangs are too small to puncture our skin.”This myth is mostly untrue. While Harvestmen are harmless to humans, they are NOT spiders – they’re closer kin to scorpions and mites. Additionally, they don’t have venom, though they do have some chemical weapons and chemical defenses. Some species, however, rely more on physical armor than chemicals.

This Ecuadorian Harvestman sees no reason to limit itself:
it has spiny armor and is putting chemicals on an arm, which it will then use as a whip!

While many people call Harvestmen “Daddy-Long-Legs”, this common name is rather vague, and I try not to use it. It can also refer to Crane Flies and Cellar Spiders, and I prefer being specific. Incidentally, the harvestmen myth is equally untrue for those two organisms as well.

Unlike most other arachnids, Harvestmen aren’t primarily hunters. Actually, many Harvestmen prefer to eat things that are already dead… They’re great scavengers, happy to eat dead vertebrates, dead invertebrates, and even droppings. One European species has been claimed to hang about bee hives, eating the dead worker bees that worker bees on the custodial shift are tossing out.

Harvestmen are beneficial for our gardens though, because they can and do hunt small insect pests such as springtails. They use their tiny little pinchers and fancy chemical glue to catch their prey. If you’d like to see their feeding behavior yourself, I’d suggest waiting by a porchlight at night – I’ve found that they like to ambush and eat little moths. If you’re a bit more hands-on, Harvestmen are easy to keep in captivity, and could make a great science project (drop me an email if interested in more details).

As for why my Harvestmen was still alive in the refrigerator, these invertebrates tend to be Cold-Tolerant and Freeze-Avoidant. They’d prefer to be warm, increasing their odds of survival, so in autumn one can find large aggregations of Harvestmen. Sharing warmth, sheltering from the elements, and trying to survive the winter. This overwintering behavior frequently happens in caves, though in eastern North America, Harvestmen also overwinter in leaf litter.

A disturbed aggregation of overwintering Harvestmen from a cave in Northern Tennessee.

What have you observed Harvestmen doing?
Hunting? Mating? Overwintering?

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