While the arrival of the Fourth of July may signify fireworks for many of us, for diehard fly anglers, the Fourth means another explosive event that occurs on Maine’s lakes and ponds: the hatch of the hexigenia limbata, one of Maine’s largest mayflies.

Known to most anglers as the hex hatch, this flurry of insect activity leads to exciting fishing.

“Up this way, it is almost like clockwork come the Fourth of July,” said Tim Obrey, a regional fisheries biologist based in the Moosehead region for the Maine Department of Inland Fisheries and Wildlife. Obrey plans a weeklong fishing trip each year to coincide with the hatch.

“It’s one of the few times of the year when you can catch really big fish on dry flies,” Obrey said. “All the data that we have collected on trout ponds show that the biggest fish of the year come right after ice out, but a lot of those fish are coming from under the surface, not dry flies. During the hex hatch, those big fish will come up to the top.”

Hexes are the largest mayflies that you will find in Maine, and they spend 12 to 24 months as nymphs underwater. You will find them in nearly all Maine waterways. Come the start of July, these nymphs ascend to the surface from the bottoms of lakes and rivers to shed their shells and take flight. They usually mate within 24 hours, and the females deposit their eggs at the surface of the water and the cycle starts all over again.

When these nymphs are struggling to shed their shells at the surface, trout and salmon take notice, and the fishing can be fantastic.

“I’ve seen hexes popping off Moosehead in October before, but only one or two individuals,” Obrey said. “The best of the hatch, the Fourth of July, is the date that I use for a reference point since the hatch seems to be heaviest at the start, and the fish seem to take them more readily at the beginning of the hatch, the first few days. After that, things start to peter out a little bit.”

One unusual aspect of the hatch is the time of day when it occurs. The hatch generally begins at dusk, so anglers need to be patient. As the sun starts to set, some anglers may head in to shore thinking they have missed it, not realizing that it hasn’t even started.

“Anglers need to hang out until dark, and sometimes even a half hour after dark is when it really gets going. So you have to be patient — a lot of people bug out early,” Obrey said. “There is definitely a cycle to it. You may see a few bugs popping around 7 or 8 o’clock at night, but the magic hour is between 8:30 and 9:30.

“It can be one of the funnest times to fish because when they are on the hexes, you see the fish,” Obrey said. “You will see them rise four or five times and you can lay the fly out there, ten yards ahead of them and you are sight fishing, waiting, and you now that fish is coming — you’re like a coiled spring. You have to do that one second count before you set the hook so you don’t rip it out of his mouth.”

Fly-fishing at dusk and into the night does bring its challenges. You need to be prepared. That means a flashlight or headlamp, and if you are in a boat or canoe, extra rods, with the proper fly already tied on.

“You want two or three rods, that’s one of the tricks of the trade because it is hard to undo a birds nest or tie a fly on when it is nine o’clock at night,” Obrey said.

And of course, you will need the proper fly. No sense fooling around with small mayfly imitations. You need something large that floats well and that you can see in the diminishing light. Patterns that work well are large emerger patterns and Wullffs.

“You want to have a fly that floats high, that floats well so you can see it. You have to silhouette the fly in the setting sun to see it a lot of times,” Obrey said.

According to Obrey, just what fly works the best may no longer be open to debate.

“Of course I have the secret fly — every one of them,” said Obrey, who ties his own, rather large and buoyant creation. “I am the envy of” my pond (name withheld to protect the writer).

It’s called the Sexy Hexy, and it’s big and buoyant. And if you are lucky enough to find Tim Obrey this week, he may even give you a glimpse of the fly. If he doesn’t, well, take solace in the fact that you know you are fishing the right pond at the right time for Maine’s hex hatch.

Mark Latti is a former public information officer for the Maine Department of Inland Fisheries and Wildlife and a registered Maine Guide. He can be reached at:

mlatti@gmail.com