More than you need to know about sulfurs.

I'm back in Lafayette helping my wife restore order to the house after the instillation of new carpeting. Jean has gone to the store so it's a good time for a break. 

Jim N. asked about the sulfur hatch and if the "Sulfur Zone" was starting to come alive.

 First of all, there are two different sulfurs that make up the bulk of the sulfur hatches on the Delaware River System. The Invaria is the larger one and it appears as early as the middle of May (some years even earlier down near Callicoon). It is one of the banes of my existence. I spend more time unsuccessfully  looking for the Invarias than any other hatch. I seem to have no trouble wading into places where great numbers of their empty nymph husks are floating by but being in the right place at the right time for the hatch seems to escape me. The hatch generally moves up stream but is temperature related so it can jump ahead and then reappear again downstream the very next day. The invaria are a good sized bug (think 16's), taste good and the trout love them. Unfortunately a good deal of the feeding is on the nymphs as they approach the surface rather than on the duns themselves.

The Dorothea is the smaller of the two and is the one primarily responsible for the "Sulfur Zone" fishing of July and August. My fishing logs show them well established sometimes as early as the 20th of June but most years it's the first of July before they really turn on up in Deposit.

At present both flies are hatching, often in the same place at the same time. Unfortunately a good deal of the feeding is on nymphs as they swim towards the surface to hatch. During the latter portion of the day's hatch when nymphs are harder to find, the trout will be more likely to take the duns. I don't think the trout feed on one type of fly to the exclusion of others. They are opportunistic feeders and will eat what appears before them as long as it doesn't have a hook in it. If you are looking for a sulfur hatch below Hale Eddy you are most likely to find it late in the evening as the water cools. Above Hale Eddy think mid afternoon when the water warms up above 50 degrees.

 The spinner falls most nights come at  dark. Listen for the "glups".  They are a sure sign the trout have switched to the spinners. A well placed spinner will be taken readily, just be sure you make the fly change to a spinner while you can still thread the tippet through the eye of the hook. If you wait until you hear the glups it's too late.