Trout Diet

Stoneflies (Plecoptera) are different from mayflies and caddis in that they require highly oxygenated water so they locate in faster waters.  The nymphs and adults are medium to large in size, with some adults reaching over 2 inches in length.  From the egg, Stoneflies have only two stages, nymph and adult.  The nymphs crawl around rocks and debris at the river bottom.  They aren’t very good swimmers, so one caught in the current is helpless and trout will key in on them.  When it reaches maturity, it actually crawls out of the water onto rocks, logs, trees, or the bank itself to split out of its exoskeleton.  The adult looks very similar to the nymph, only with the addition of wings.  Keep an eye out for the split cases during stonefly hatches.  If you see them and they are not completely withered and dried, chances are the trout are feeding on stoneflies; of course, the big flying bugs near the water should give it away.  These flies live near the banks for a few days until they journey farther away to mate.  Then the females come back to the water to lay their eggs.  Because of their size, and their clumsy way of depositing eggs, trout go crazy for these when they are on the water.

Finally, we come to Midges (Diptera).  Many different flies fall into the Midge order, including gnats and craneflies, and many, like the mosquito, are closely related, but are not midges at all.  Midges are by far the most prolific of aquatic fish food and in some places are the key to trout survival when it is too cold for other insect hatches.  In most places where there are trout, there is a consistent midge hatch all year long.  Often, when there are no other hatches, trout will feed exclusively on midges.  Similar to the caddis, the midge larvae are thread like and stay near the bottom.  When it matures it becomes a pupa, drifts, and hangs just below the water’s surface before emerging as an adult.

The wise fly fisherman will have a wide variety of flies to imitate the various aquatic insects and their different stages.  Some will have a separate fly box for imitations of each of the four major orders.  Now, just so I don’t frustrate those entomologists out there, I’ll mention a few other aquatic bugs to keep in the back of your mind.  There are dragonflies, alder flies, damselflies, and water boatmen.  It is also worth mentioning Leeches and freshwater shrimp (scuds) because they are also very tasty to trout even though they are not really aquatic insects (These last two can have great results when fishing an effective imitation).