It is one of the great mysteries of life: from whence come spiders and insects? What is the origin of life itself? At the beginning of the Scientific Revolution, there were theories of spontaneous generation. When I check Wikipedia, it goes back to Aristotle who believed that aphids sprang from the dew on roses, mice from dirty hay, and (one would think) fruit flies from aging fruit. Clearly from this photo, Aristotle would think that spiders sprang from unused bathtubs.
The bathtub is in our summer cottage and the spiders just appear. It's not like there are masses of webs on the ceiling, with thousands of wannabe Charlottes angling and dangling for a chance at pictorial fame on Blogger. No! The ceiling is quite finished and well maintained. So from whence come all these spiders? Inquiring minds want to know!