Easy to identify, Mayflies have a transparent wing post that looks like a sailboat. Most Mayfly patterns can be imitated with the same pattern just by using different sizes and colors. Common Mayflies throughout Colorado include Blue Wing Olive (BWO), Pale Morning Dun (PMD), Drakes (green and grey), Quills (red & brown) and Tricos. After spending most of its life underwater as a nymph, a mayfly swims to the surface to hatch. During this swim up (emerger stage) the emerger hatches into a dun, which while on the surface is a primary food source for trout. The dun then flies off the water to nearby foliage where it undergoes another transformation. At this point, it becomes a spinner, which will join others and be seen swarming over the surface in mating flights. Some spinners will drop their fertilized eggs, others will touch down on the surface to deposit their eggs. With the act of renewing the species complete, the spinners fall to the surface to be eaten in great numbers by the trout.

Very abundant in Colorado, the Caddis fly can tolerate all types of water conditions, although they tend to prefer cool clean water (hence their love of Colorado). Caddis are one of the more abundant stream-bottom insects, to the point where they can produce prolific hatches, where insects literally "blanket" the river banks and shores. The caddis fly begins its life in an egg, and after the egg stage the insect spends most of its life in the larva stage, where it is encased in a protective shell it manufacturers either of small sticks or pieces of gravel. When its ready to hatch, the caddis swims up as a pupa, and rides on the flow of the river where it may be taken by a feeding fish if it doesn't escape to a nearby shore as an adult. When adults have mated, some deposit their eggs on the surface of the river, while others will swim to the bottom to deposit their eggs, and then swim to the surface again. It is these diving caddis that anglers frequently confuse with hatching caddis.

The Stonefly also referred to as a Salmon Fly or Willow Fly, is a staple food source for Trouts across the state of Colorado. This insect is unique in that it only has 2 life cycles, the nymphal stage, and the adult stage. Once hatched, the stonefly nymph crawls along the bottom of the river and will crawl towards the river's edge, as opposed to other insects who go through an emerger state. The life-cycle of a stonefly nymph is 1-3 years, during which time they are prime suspects for a trout's diet. Stoneflies are often considered to be a primitive insect, and are easily recognizable by their size, as they are the largest of the aquatic insects. Their presence in a stream or still water is usually an indicator of good or excellent water quality with healthy oxygen levels.

A small two-winged insect group found in virtually every freshwater environment. Midges are a year-round insect, where they play an important role in a trout’s diet, especially during the winter months when rivers are nearly void of insect life. While they are commonly present on most fishable trout water, they are incredibly small with the most effective sizes being between size 18 and size 24. With that said, on lake and still water environments you may see arger sizes 10 – 14’s for still water fishing. Grey, red and black is always great color choices.

Terrestrials, or land-based insects, are another staple in diets of trout. Terrestrials include grasshoppers, crickets, ants, beetles, and just about any other bug that might get knocked down into the water. Although not "hatching" insects, terrestrials make up a significant portion of a trout's diet. On many western streams, using a grasshopper during the summer months can create a memorable fishing experience.

Like terrestrials, Eggs and Worms are not hatching insect, or even insects at all. But they are an important food source, as they are very high in protein and offer substantial substance in a small package. Worms can be found in most any freshwater environment, and are great to fish during our after rising water levels. Eggs will be available during spawning periods in the spring (rainbow and cutthroat spawn) and fall (brown trout, kokanee and brook trout spawn.