Some Baetis swim to the bottom to lay eggs. But there are several species of stones that do hatch from the water including the ones from this time of the year, but a small minority of them.

Sandfly - I can't see what you posted beyond "...how they hatch:"

Did you forget to paste it in or am I missing something?

I had the same experience on the same day. Trout chasing bugs everywheres on a flat that varied from 18" to about 30" deep.

I tried skittering a black Caddis and had two refusals, I tried a soft hackle(tandem) fished on the swing and nicked one but then nothing. They were leaping out of the water chasing the stones when they would land on the water. It looked to me like they were really chasing something emerging.

It was hard to tell if they are slashing at flies on the surface or chasing emergers.

I finally switched to a bead head Pheasant tail, size 16, fished under an indicator. That was the ticket I caugt five fish in about 35 minutes. Just when I was congratulating myself for being good at this I fell in! Water Temp 43 degrees and that was the end of the stonefly hatch for me.

here it is, they do not swim to surface they might lose their hold on the bottom though.

A Streamside Introduction to Stoneflies • 29

While all stoneflies are herbivores in their early nymphal life, certain types become carnivores soon after attaining about a quarter of their growth. Being herbivorous or carnivorous is not a function of size; it actually depends on when the nymphs accomplish their growth for the year. Winter-spring members are the most active and grow fastest during the first five months of the year. This coincides with that period in which trout streams support liberal amounts of decaying leaves deposited the previous fall. Thus the fierce-looking Pteronarcys nymph is mainly a herbivore at the outset and remains so throughout its entire life. Summer emergers, which enter a long egg diapause, do not hatch until late in the year and will not attain appreciable proportions until the following spring or the beginning of summer. They then become carnivorous, feeding on the abundant aquatic life (mayfly nymphs and caddisfly and midge larvae) that overruns the bottom of most trout streams. The best example is the large Acroneuria (Big Golden) and related types. These are fierce in appearance and carnivorous in nature—a dangerous adversary that all aquatic insects must escape from or be eaten by.

The mechanics of actual emergence, which begin to take place once the desirable water temperature or photoperiod is achieved, are exemplified by the nymphs crawling to shore on the stream bottom and up on half-submerged rocks or any other suitable object at the margin of the stream. If there is one basic consistency among stoneflies, it is this aspect of their life cycle. The adults then will require ten to fifteen seconds to emerge out of the nymphal shuck. The adults must wait some moments before their soft bodies and wings harden, then they will scurry away to a hiding place in the streamside vegetation or simply fly away to nearby trees. Some species of the little Capnia barely venture far and will spend their entire four-week adult life within close proximity of where they appeared from the stream. The larger types capable of good flight usually fly away to the trees. Semiwingless forms have no choice but to remain close by.

The early little stones have been the thickest this year that I can remember. I've been out a couple times in the last few days on big warm water rivers and the stones have been everywhere (no bass, or even fallfish, were feeding on 'em). I watched swarms of 'em on the Juniata yesterday - these were the larger "brown" stones - and they seemed to emerge right out of the water like caddisflies. Perhaps it was an illusion but I watched for a good time as this was one of the densest and largest stonefly hatches I've ever seen in PA.

Hmm...I'm thinking an experimental soft hackle stonefly is in order. But, I still have to believe it was mostly a masking hatch on Sunday. Otherwise I have some wounded pride to deal with

Fished a nice little brookie stream on Sunday, fish were coming out of the water left and right, thought it was a caddis hatch, got 6 nice size brookies on a size 16 caddis x-emerger, and missed 10-15 others. I then realized it wasn't a caddis but a stonefly, switched to a stonefly (dry) near the end of the hatch, and got 3 more, and missed approximately 5 others. Hope to get out this coming Saturday or Sunday and use the right fly this time, which I believe is around a size 16 dry stonefly with a grey body and dark charcoal/black swept-back wings.

There were large brown stones on the west branch of the Delaware today. I didn't see a single rise to them. It wasn't a prolific hatch at all. I took all 3 of my fish on nymphs in fast water 8-10 inches deep.