Friday, October 7, 2011

Peltoperlids (Roach-like stoneflies): Tracking the Changes

The Peltoperlids (Roach-like stoneflies) we find in our streams are genus Tallaperla, and whatever the species is that we find in our streams, it seems to be univoltine: i.e. it has a one year life cycle.  Our Peltoperlids mature and hatch in late spring, lay eggs, and the young larvae appear in the summer.  Naturally, development dates vary from stream to stream.

Since I've been taking photographs of Peltoperlids for almost a year, I thought it might be worthwhile to show how these nymphs change and develop during that period of time.  As with almost all mayflies and stoneflies, Peltoperlids become darker in color, while patterns are more richly defined, as they grow and develop.  We can trace those changes in the photos below.

6/1/2011: small tributary to the Moormans River.  I'm very pleased with the clarity of this photo since this nymph was really small.  The cycle begins.

9/6/2011: the Rapidan River.  Notice how the colors have darkened.

2/23/2010: the Rapidan River.  Distinct patterns now show up on the wing pads and pronotum.

4/20/2011: small tributary to the Moormans River.  Note how the patterns and colors on the pronotum and the wing pads are more pronounced.  The edges of the wing pads have started to darken.

5/4/2011: the Rapidan River.  This one is ready to hatch, the black edges of the wing pads are a sure indication of that.


The photo at the top of the page was taken on 6/13 on another tributary to the Moormans.

Peltoperlids are not found in a lot of our streams.  They prefer small, cold water, mountainous streams, and they like to roam around in the leaf packs.

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