Mayflies, caddisflies and stoneflies.
Essentials of a trout's diet.
The mayfly, order Ephemeroptera, is usually thought of as having a very short life span since the adults typically only live for one day. However, the aquatic form of a mayfly, known as a nymph, lives underwater for a year or more. Mayflies undergo incomplete metamorphosis which includes egg, nymph, and adult phases. Mayflies have a unique adult phase as they molt from their initial, sexually immature form known as a 'sub-imago' or commonly as a 'dun,' into their sexually mature form known as an 'imago' or 'spinner.' Adults are characterized by upright wings, often referred to as 'sailboat wings,' cylindrical bodies, and two or three usually long tails. Mayflies are not very tolerant of pollution so their presence can be an indicator of good water quality.
The caddisfly, order Trichoptera, inhabits diverse habitats and is widely distributed across the globe. They can be found in cold, fast mountain streams, warm stillwater, and everything in between. Adult caddisflies are characterized by tent-style wings that fold over the body when not in flight, no tail or tails, and prominent antennae. Caddisflies undergo complete metamorphosis which includes egg, larva, pupa and adult. Caddisflies are tolerant of pollution and the presence of heavy metals so they can have strong populations in streams and lakes that are completely devoid of less pollution-tolerant orders like mayflies and stoneflies.
The stonefly, order Plecoptera, is a widely distributed order of insects that is believed to be around 300 million years old. Adults' appearance is characterized by wings held flat to the body, often veined in appearance, usually long, prominent antennae, and two stubby tails. The nymphs have a unique appearance with thoraxes divided into three distinct sections covered by armor-like plates. The stonefly order goes through incomplete metamorphosis which includes egg, nymph and adult phases. Stoneflies are the least tolerant of pollution of the three orders covered here, and their presence is an indicator of excellent water quality.
Try searching Hatchpedia using the single keyword 'mayflies', 'caddisflies', or 'stoneflies' with the 'Use my location' and 'Use current date' options selected to see insects that hatch in your area this time of year in a photographic list.
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