Even in the winter you can find cool stuff by overturning rocks found in creeks. As the name “Stonefly” implies, they typically crawl around under rocks in streams. These are ancient insects of a very old and stable lineage. They have changed very little in the last million years. They are the aquatic, immature stage of a fairly short-lived winged adult insect.

To make their final transformation, the nymph crawls up overhanging roots, vegetation or rocks protruding from the water, sheds its skin, and flies away as an adult. Adults engage in an interesting behavior known as “drumming.” When drumming, stoneflies strike themselves against an object, producing a signal of pulses and pauses.

Stoneflies are usually associated with well oxygenated streams or sections of lakes with plenty of waves. They are predatory on a variety of other aquatic insects and invertebrates.

They are not just cool to look at, they are also an important part of stream and river fauna, providing food for fish and birds. Their absence is often a good indicator that a stream is polluted. These insects are so important that conservation agencies and game fishermen keep charts of when they hatch.

Third Eye Herp
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