Most were scampering a few feet behind the idling machine. Since we were collecting spiders on an oil-producing island, this seemed fair. The diesel vibration technique is brand-new, and these arachnologists are among the group that stumbled upon the phenomenon a few years ago. They received a suggestion from a farmer in Adelaide, who noticed that when he sat idling in his tractor, he often got uninvited visitors. Nobody's had time to publish scientific papers yet, and the arachnologists have divergent theories about what works when, where and why.
Ground rumbling seems the most obvious answer to the why question.
These animals live under rocks or leaves or in the top few inches of the earth, and they're programmed to equate vibrations with food. But the technique doesn't seem to work as well in heavy wind. Julianne thinks the smell of diesel actually adds to the appeal, and that's why the spiders don't come out when the fumes are dissipated in a breeze. I think the ground spiders simply know not to venture into a Western Australian coastal gust, lest they become little legged Frisbees. And tonight we're a fast-food restaurant for the arachnids.