Sunday, September 09, 2018

Greedy, Take Two. Or Six.

A week ago I posted the story of a spider and her fruit fly dinner. She had dashed from one end of her web to the other within seconds to catch two flies at once. I wondered then, what would happen if I gave her three flies.

Last night, I took the lid off the fruit fly trap beside her web, and this time a half-dozen flies were caught.

The spider leapt into action, took two steps and stood there, frozen, confused maybe by the signals coming from all sides. She thought about it for a few minutes, then went slowly over to the nearest fly, grabbed it and wrapped it up.

Then she left her dinner hanging, and went for the next, brought it back and wrapped it with the first. Rinse and repeat: she caught all 6 fruit flies and bundled them together before she settled down to eat.

Big meal. The red colouring is fruit fly eyes; 12 of them.

So that question is answered.


  1. And I'm sure those eyes were wide open in fright. I get very few spiders here in the cabin, but a few show up outside around the deck. - Margy

  2. I did similar experiments before in an attempt to better understand how an A. Diadematus spider's injection of venom prior to eating works. Conventional knowledge is that the spider injects venom, which has the dual purpose of beginning the digestion of the insect, then it drinks the soup once digested. But if it were that simple, a collective ball of insects would have some better digested than others.
    My refined theory is that the spider injects digestive fluid as needed. When the insects are proportionally large, the spider would need multiple bites to ensure thorough digestion, giving this theory some plausibility. Similarly, multiple insect-balls would need multiple bites. Furthermore, when insects are proportionally small (like the fruit flies), the entire insect becomes liquified, and some of that digestive juice is bound to come in contact with other the other insects, aiding in digesting the entire ball together.


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