Prom Night From Hell

by Steve May - November 27, 2007

Fishing a “hatch” is a great time to be on the water but understanding what is going on can really improve your success at fishing these exciting events. To make things easier to understand I like to relate a hatch to a teenage prom night slasher movie. Aquatic insects live a tragic existence. But, their tragedy is a huge bonus to fly fishers.

Mother nature has planned things out so that each mayfly species lay their eggs at roughly the same time each season. This makes predicting when you need to be on the water with a particular imitation easier. Mayfly nymphs spend several months eating algae and avoiding predators on the bottom of the river.

Many species of mayflies, and other aquatic insects, live in areas with good water flow. The water brings food but areas of high flow can be dangerous and bugs are regularly swept away and eaten by waiting fish. When you do not see bug activity on the surface it is a good to fish a nymph near the bottom below areas of fast water.

Things get more exciting as mayfly nymphs mature. Like hormonal teenagers, these bugs prepare for their upcoming “prom night”. In the days before the hatch event they grow wings under their skin and become more active and anxious about the upcoming prom night. During this time large numbers of bugs loose their grip on the bottom and are part of what fly anglers and biologists call “the drift.” Trout are on the lookout for these easy victims. Imitating drifting nymphs at this time can get you hooked up a monster of your own.

When conditions are right, mayflies prepare for prom night. Mayflies make a break for the surface en mass. They are not the best swimmers and as they make they way towards the surface the carnage is significant. Despite the full trout bellies, many insects make it to the surface shed their nymph skin, dry their new wings and fly away. When this “emergence” is happening using a nymph, emerger or wet fly pattern in the main water column or in the surface film can be really effective. Many bugs have problems with breaking through the water’s surface and this provides an opportunity for fish to gobble these hapless bugs.

The epic journey is not yet over. The winged insects must fly to bankside vegetation. Airborne killers (birds) are waiting to ambush them, Mayflies that avoid the squadrons of birds shed their dusty emergence clothes for formal wear. Mayflies shed their skins and become elegant insects with clear wings and long tails that are ready for the big dance of life… or death.

Dressed in their “formal wear”, the male bugs return to the river to fly over riffle areas waiting for the females to arrive. Then amidst dive bombing birds the insects match up and make out while flying over the river.

After the love is over, males expire and fall to the water. The females deposit their eggs into the water and then join the males in a tragic drift of death downstream. This is when you can imitate a spent mayfly and get some revenge with a murderous trout.