I've found that springtime is the best time to get your money's worth out of a thermometer. On an April day, blue-winged olives will begin to hatch on cloudy days at around 40 degrees. On that same day, caddisfly pupae begin to drift in 50-degree water, give or take a degree, with an emergence at around 55 degrees.

What time of year do caddis flies hatch?

April through October. Emergence and egg laying commonly occurs during the morning or evening hours.

How often do caddis flies hatch?

Most species of caddis emerge (hatch) intermittently through the day or night, with multiple species (and therefore, color & size) hatching each day. This generally keeps trout from becoming super selective on just one size, color or stage of an insect hatch, and they become opportunistic feeders.