That's a very good possibility, Jeff.
Hydropsyche/Ceratopsyche species are especially prominent during the seasonal "mayfly lull." On most Northeastern streams, after the early season Blue Quill, Quill Gordon, and Hendrickson hatches wind down, caddisflies become the main hatching activity until the first of the large early Sulphurs appear.
On the J, I would expect that
Hydropsyche/Ceratopsyche species comprise some of most important hatches as the Grannoms decline. I often see fly shops posting "olive caddis" on their hatch boards from now through the first weeks of May, and I believe it refers to one of the
Hydropsyche/Ceratopsyche species--probably
C. bronta. Here's Gary LaFontaine's description of the timing of
bronta:
The peak of emergence seems to occur just as the weather turns nice for the season in whatever region it is in.
The current heatwave is forcing earlier emergence. I had hoped to get to the Poconos for the Hendrickson hatch (which typically peaks as April breaks into May on the larger streams up there), but the heat blew most of them out in a two-day blitz. They are already on the wane. Now, I'm preparing for
Hydropsyche/Ceratopsyche hatches.
Although imitations that generally suggest the larvae can be broadly useful as searching patterns, the larvae will be holed up in temporary pupation shelters prior to emergence, so I wouldn't worry about specific larval imitations around the time of emergence. I would focus on imitating the pupae. The female
bronta pupae are typically #14-16 with yellowish abdomens, and the males are #16-18 and more greenish (bright "olive"). (However, several H/C species emerge at this time, so a more tannish or brownish yellow pupa can also be useful.)