Looking for love

It's spider season, finally. After an almost spider-free winter, suddenly there's one in every corner and under every piece of furniture. Most of them, so far, are small.

Reflected in the kitchen sink. Female, about 1/4 inch long.

The last few nights, a clutter of little runners has been searching my walls and ceilings, searching high and low, back and forth, hurrying, hurrying. Every time one comes close enough, I can see that he is an adult male; it's mate-finding time.

All night, every night this week, they ran and ran. Every time I woke up, there they were. In the mornings, they've been gone; no sign of them anywhere.

Kitchen counter spider.

I told one he was looking in all the wrong places; "There's a female behind the microwave," I said, but he wasn't listening and kept cross-hatching the wall over my desk.

I wonder; how do spiders ever find their mates? The males don't waste time looking for food, and they must run out of energy sooner or later. Jumping spiders have good eyes, but many do not. Jumpers also make noises, tapping and rubbing bristly legs together. Some, the web builders, just have to find a thread of silk and follow it up. But these running spiders? They don't seem to be following a pheromone trail, because their search seems completely random.

I googled it, and found others asking the same question, and not getting much of an answer.

That’s a very good question, in the sense that it’s a request for information which is not so easy to find, but is quite interesting! Many arthropods communicate in various ways by means of chemical cues - such as hormones that are released (often in surprisingly small amounts) and picked up by another individual. These may signal the presence of something dangerous or something desirable, and may lead the receiver to the source of the ‘odor’. Airborne pheromones can lead moths to a willing and receptive female (or to a Bolas Spider who is using these signals to bait a trap). Spiders can add pheromones to silk strands they lay down as they travel, or as part of the web. The former would be encountered and ‘tasted’ by a spider which comes across the strand, and the latter would also be wafted off on the breeze for a male spider to follow to its source. I haven’t seen much work on this yet, and it would make some neat projects. (Answer on Quora, by John Robinson)

I wonder how far a male has to run before he finds his girl?