The Nocturnal Stone also known as the Midnight Stone or “Mr. Midnight,” is one of the lesser known stonefly hatches we see on the water around Southwest Montana. Nocturnal’s will hatch on most freestone rivers in Southwest Montana. However, if you like to sleep in or get off the water early you’ve probably never seen any of these bugs!  

When Nocturnal Stones Hatch:
Nocturnal stoneflies will typically get started around the end of July to the beginning of August; however the last few years we’ve seen them get started in early to mid-July because of light snowpack and early heat waves. The hatch generally lasts a month, ending in mid to late August.  

Just like their name implies, nocturnal stones hatch at night which is why a lot of anglers have never seen or heard of the bug at all. They crawl out of the water at night onto dry river rocks where they shed their exoskeleton and transform into adults. The males are completely incapable of flying which is another reason that a lot of anglers haven’t actually seen the bugs themselves. What they lack in flying ability they make up for in their ability to skitter across the top of the water which makes them an ideal bug to imitate with fly patterns. If you arrive at the river and see stonefly shucks on the rocks but don’t see any adults, this is a good indication that the nocturnals have been out and fish will usually be keyed into them.

What Patterns to Use:
The most popular pattern to imitate the nocturnal stone is the Chubby Chernobyl. This fly pattern works so well because it is offered in a number of darker colors such as royal, black and tan, and the most popular color, purple. The Chubby is also a great skater and floats well making it incredibly effective at imitating the skittering nature of the nocturnal stone. Ideal sizes are eight and ten but you can fish them from a size four up to size twelve. Because the nocturnal hatch is not well known, there aren’t a large variety of patterns tied specifically for them. The Yellowstoner Mr. Midnight is one of the only commercially tied patterns specifically imitating the nocturnal stone. That’s not to say you are limited in the flies you can use, you’re mainly looking for a pattern with a dark body, some rubberlegs, and foam to make it float. Dig through your golden stone or salmon fly box and don’t be afraid to take a sharpie to your favorite stonefly pattern to achieve a nice dark body!  

If you’d like to target trout with nymphs you can fish your standard rubberleg stonefly patterns in darker colors. Patterns such as Pat’s Rubberlegs, Delekta’s Mega Brown Stone, and Mega Pheasant Tail are great imitations of their nymph form.  

How to Fish the Hatch:
Because nocturnal stoneflies don’t hatch during the day, the best time to target fish using nocturnal patterns is during the first and last hours of daylight. If you can get to the river before the sun breaks the top of the mountains you’ll be fishing in prime time. The same goes for when the sun tucks itself behind the mountains at the end of the day. Once on the water aim your cast as tight to the bank as possible and twitch/strip it off the rocks into the feeding lanes. Casting tight against the rocks and making a big ugly mend is another good technique. The mend will pull your bug off the rocks in one quick motion, just be ready to set as you’ll have a lot of trout strike just as your bug stops moving. The best part about fishing this hatch is the fact that you can pop, skate, swing, and twitch your fly to entice hungry trout. Dead drifting is actually much less effective than giving your fly movement making this a great hatch for beginners who don’t have their mending down.

The nymph stage of nocturnals crawl around the rocks with extreme vigor so again, twitching and swinging your nymphs can be very effective. Dead drifting nymphs will also work but fishing these nymphs under your dry fly while giving your dry plenty of action will usually bring the most fish to hand.

If you have the determination to get up at dawn or fish until dark the nocturnal hatch is an extremely fun hatch- it’s my personal favorite hatch of the summer!