As I write the rain is lashing down. I think of all those insects that can be trapped in a drop or two of water and drown in a pool of just a few drops. They can’t evade the rain by flying between the drops. Why are there any left after a hard shower?
On the underside of things, mainly. The underside of leaves, under bark, under cracks in walls or rock…and under stones.
The itsy-bitsy spider crawled up the water spout…
I know, I know, you didn’t ask how arachnids survive downpour.
I’m guessing that most insect can sense the impending rain and seek refuge before it begins. If you take notice, they usually seem pretty scarce just before it starts.
Surface tension also plays a part.