Bug Bits

The essence of fly-fishing can be distilled down this: Enticing a fish into believing that what we are offering them is something that they would normally eat, or at least something worth a quick taste. Ours is a sport of imitation; of mimicking, as near as possible, the appearance and actions of the various organisms that swim, crawl and wiggle in the trout’s world. Fly fishing is also a sport of deception – bits of fur and feathers tied to a hook that upon close inspection may at best have a rough resemblance to the food item we are trying to duplicate. Add to this the often selective nature of trout and the seasonal availability of most invertebrates and it stands to reason that knowledge of the habits and biology of the various food items that trout feed on is an important component of the fly angler’s tool box.

Baetis sp. nymph - an example of a simple yet effective fly pattern

The bulk of a trout’s diet is made up of aquatic invertebrates. Trout also eat the occasional small fish, or even the odd mouse or frog – but this component represents less than 1% of the average trout’s food intake. Granted, larger fish are more inclined to target larger food items when available, but even they do not discount the nutritional value in eating sufficient numbers of small bugs (a 200 pound black bear taking the time to tear open a rotten log for a mouthful of insect larvae is another prime example of this).  Aquatic invertebrates are an important link in most aquatic ecosystems; converting energy from green plants, organic debris, and microorganisms into nutrient dense biomass that larger animals are able to capitalize on.  This link not only allows trout to thrive in lakes and streams, it forms the foundation of the sport of fly fishing.

Claassenia sabulosa nymph (Plecoptera) - a common stonefly on some trout streams

So it is with the subject of aquatic invertebrates that our journey into aquatic “entomology” begins. I have put entomology in quotes because in the strict sense, entomology is the study of insects. But in this section (Bug Bits) I will be covering more than just insects – I will also touch on some of the non-insect organisms that trout feed on. My goal is to provide background information over the coming months so that when we begin to discuss current hatches over the summer, we can cover the subject in more advanced terms.