You know what a "White Miller" is? No, you probably don't. Know why you don't know what a "White Miller" is? I do.
White Millers are a common name for some very light colored Caddis...they look white in flight. They get over the water, especially the water's edge, in massive courting flights which the common angler calls a hatch. They aren't hatching though and they aren't landing on the water and the fish don't give a shit about White Millers. The only thing on this earth, that I know of, that cares about White Millers are people that fish the Firehole.
(Full Disclosure here...I know nothing about the life cycle or importance of White Millers...technically speaking, so these deductions are based solely on my experience. The last tine I fished Horseshoe Bend on the Firehole, I did so in in Surf Shorts and a Dead Kennedy T-shirt on opening day while smoking unfiltered Pall Malls. I wanted to get pool toy out and tie up to a mid-river rock the water was so hot. Never did understand why people think they need waders to fish the Firehole!)
White MIller's are out thick right now on the lower and upper Madison too. Still, nobody comes in talking about the White Millers. Guides are texting each other that the White Millers are out. Fish aren't podding up to gorge themselves on White Millers. The White Millers are, in fact, so uninteresting that even the White Miller's dont seem to care about each other. They just fly upriver in frantic randomness. I've never even seen birds eating White Millers.
I sat under a tree yesterday, in a lightning storm, watching White Millers and thought to myself that this is a truly worthless hatch. The Brown Drake nymphs should focus on eating White Miller larva next year and replace them in the food web. Brown Drakes are cool bugs that do interest fish, birds, and anglers.
In my 25 years of hanging around this part of the world, I have only ever met one type of character that cares about the White Mille. It's the occasional Fireholer. They can be smack dab in the middle of PMD or Black Caddis Hatch with fish rising all around them and they are frantically searching for a White Miller Pattern. They pester fly shops and troll consumer fly fishing shows back east trying to prod some reel-known fly tying celeb to tie them up some White Millers. My eyes rollback and I get some palsy stuff in my right cheek when someone comes in and asks me if we have White Millers.
Th truth is, we carry plenty of little, light colorer and even a few white size 16 dry flies (small spruce Moth patterns) that accurately represent a Whiter Miller. They don't work, though, for that occasional Fireholer though as the bin is not labeled "White Miller." I know we could put a "White Miller" label on a size 16 yellow stimulator and rell it to that angler just as well though.
Fish don't care about White Millers and thats why fly shops and guides generally don't care about "White Millers" either. If you are fishing on the Firehole, and the fish are rising madly...they aren't eating White Millers. Quit lying to yourself and come to terms with the fact that a small PMD dun or emerges is really what you need on 5X or 6X. Of course, the real trick is to get the fly to the fish. Quit wasting gas and oxygen, looking for a the mythical White Miller fly pattern and focus your energy on learning to cast 25' with some degree of accuracy and delicacy. It's not the fly, asshole and it certainly isn't the White Miller!