As far as I can tell, fireflies and rainbow firefly can also be caught in the morning. I got fireflies at 11 am and a rainbow firefly one hour later along the river (between the two fishing spots) in the forest. I also got some others at night.
As for spawn spots, I noticed three in Deep Woods, one near the herb garden (uncommon insects?) at daytime, one about 15 yards from the head of the Hermit's bed (north-west if you face the bed) near a group of three trees (common insects?) daytime, and one inside the biggest patch of forest with dirt where I could find only Will-o-the-Wisp at night. The Will-o-the-Wisp seem to appear after 8pm and the insects from the other spots disappear at 8 pm.
