The spinner fall happens between 10:30 pm and midnight, the hatch usually between 1:00 am and 4:00 am. Depending on the weather those times can change by several hours and the flies don't come everywhere every night. If you are planning on fishing new water after dark get there real early and learn the area; logs, rocks and holes are much harder to negotiate in the dark. The hatch is rolling right now and will last another week or so on th PM, Big Man and AS. Rivers north of there will still be going for a couple of weeks and then the UP.when do the giant caddis hatch in northern michigan? and at what time of day?