How to match the hatch
June 17, 2017
Match the hatch is a saying that gets thrown around a lot on the river and in fly shops. What exactly does this phrase mean? The angler is trying to use a fly that accurately matches the aquatic insects in the body of water they are fishing.
There are some people in the fly-fishing community that believe that dry fly-fishing is the only way to fly-fish, because dry flies are what we are most familiar with, however there are many ways to catch fish and this article will go through the life cycle of the aquatic insects that trout target.
Aquatic insects start as very small eggs deposited in the water from the female adults. During this time, the adults bounce on and off of the water, dropping their eggs as they hit the water. The eggs make their way to the bottom of the river and eventually will start developing into small larva. These eggs are extremely small and are rarely targeted by adult trout.
Larva and Nymph Stage
After a few weeks, the eggs start to develop into nymphs depending on the bug. The eggs take anywhere between a few days to a number of weeks to hatch depending on the water temperature, conditions and species. Once the nymphs hatch, they forage on the bottom of the river and grow throughout time. Some mayfly nymphs will take only a couple of weeks to mature, while some will take up to two years before making their way to the surface.
Stoneflies will go through developmental stages within their life as nymphs, known as instars. As the nymphs grow, they shed their exoskeletons. Each period of shedding marks the end of an instar stage. Depending on the species, the nymph may undergo anywhere from 12 to 23 instars. There are studies that show eighty percent or more of trout's diet are in the form of nymphs and larvae. This is a big reason that a lot of anglers and guides fish nymphs below an indicator with good success.
This stage is specific to caddisflies, as they go through a full metamorphosis. When the larva is fully grown, it enters the pupal phase. The larvae will often form small cocoon-like structures out of small debris and adhere them to the rocks at the bottom of rivers. In these small casings is where they will "pupate" and prepare for adulthood. The caddis pupa look similar to the adult although they are covered in a protective membrane that will often make them appear to glisten. These pupa will shortly float to the surface of the water and become adults. As they are pupae, they are easy targets for trout.
For mayflies, when it is time for the nymphs to emerge, they make their way to the surface where they pull themselves free of their nymphal shuck and emerge as a sub-imago or adult fly. Caddis pupae will swim to the surface using their hairy middle set of legs. Stonefly nymphs will crawl on to the rocks along the banks or in the shallow water. These bugs will rest on the water surface or rocks and dry their newly exposed wings, this is when the caddisfly and mayflies are most vulnerable to attack from hungry trout. This stage in their life cycle is when anglers target fish with dry flies, which can be an engaging way to fish. It's a very exciting and gratifying experience to see a trout take a fly off of the surface of the water.
SPEND TIME ON THE WATER
Knowing these life cycles isn't necessary to catch fish, however it really helps to figure out if it's time to tie on a dry fly or a nymph. Take a look around, if there are bugs in the air, then it's time to put a dry fly on. If there's nothing flying, then the nymph game is going to be the best way to catch a trout. Clouds in the sky, sunny days and rain can trigger different hatches throughout any given day in the summer. As you spend more time on the water you'll see different hatches occur throughout the day. Always keep your fish wet and practice catch and release to promote a great future for our local fisheries.
Ray Kyle is the shop supervisor and guide at Vail Valley Anglers. He can be reached at 970-926-0900 and firstname.lastname@example.org