Unless one is involved in a serious project, it’s rare and very hard to observe, note, and record (photos and videos) detailed aquatic insects‘ activities. I mean, all the serious fly-fishers do pay attention on the stream and try to keep notes but our focus is fishing, especially while insects are hatching and trout are rising. Over the years, I was able to capture some interesting moments while fishing and guiding thanks to this method = stomach pumps. This is another material from my own Bighorn fish trip in early September. As reported in the previous post, I fished for a group of rising trout at a certain spot. Judging from their rise forms, some seemed feeding on PMD spinners (quiet sipping rises), while others seemed feeding on black caddis (splashy rises). According to my journal entry, I caught a fair size trout on a caddis emerged dry-fly. Then I did a stomach pump.
Basically I rescued live insects from the trout’s stomach before digested. With exactly the same way, I have recorded a PMD dun just emerging out of the nymph shuck and a midge adult hatching out of a pupa shuck.
So caddis indeed swim and fly up quickly right after escaping their pupa shucks.
Proper stomach pumping should not harm trout. So learn properly, conduct frequently, and keep your devices handy. You may come up with some interesting samples without sacrificing the fishing part.