Unknown Insect at edge of the Ventura River

Moved

… Charley Eiseman, 21 December, 2011 - 3:25pm

Sat at the edge of the river

Sat at the edge of the river for about an hour photographing mostly birds. These insects just sat on the rocks and never moved.

… Michael A. Levin, 7 December, 2011 - 2:40pm

That's because they're just shed skins

(see comment below) :)

… Ken Wolgemuth, 7 December, 2011 - 2:42pm

Exuvia (shed exoskeleton)

of a dragonfly naiad. In other words, an adult dragonfly emerged from this. Others may be able to tell you more.

Welcome to BugGuide!

… Ken Wolgemuth, 7 December, 2011 - 2:33pm

Exuvcia (shed exoskeletin)

Thank you, I've been wondering about them since I took the photographs. So this winter as the river rises they will be washed away.
Do you have any idea of the timing? I mean when the dragonflies emerge. Is there a reference that I can go to to learn more about them?

… Michael A. Levin, 7 December, 2011 - 3:00pm

Timing is dependent on specie

Timing is dependent on species. (and can be a great way to narrow down what species of exuvia you have! Most guidebooks show a flight date range and emergence will be at the very beguinie or maybe a week before that). I primarily use the "Dragonflies and Damselflies of Algonquin Provincial Park" guide for flight dates in my area.

These look fairly freshly emerged....I find those little while stringy bits degrade farily quickly (day or two if it's moist), in my experience only...

A good heavy rain will often wash the exuvia away (unless it is in a protected area ie. under a bridge, under a rock overhang).

A good look at the mouth parts can often get you down to genus or further.

From what I can see I would hazard that it is the Skimmer group: http://bugguide.net/node/view/118012/bgimage That said you often will need a microscope to see the bits you need to in order to narrow it down to species.

An online key to the larvae is here (can sometimes work for the exuvia to, if bits are not distorted by emergence): http://insects.ummz.lsa.umich.edu/MICHODO/test/HOME.HTM
I also have this one: https://kb.osu.edu/dspace/bitstream/handle/1811/3411/V44N04_151.pdf?sequence=1
and I thought I had another, a bit more beginner friendly, but can't find it at the moment.

… Brenda Van Ryswyk, 7 December, 2011 - 3:14pm

Exuvcia (shed exoskeletin)

Thank you,
I'm impressed with your knowledge and excited to have found this site and hope to use it again as I am a novice in entomology but have a love of macro photography.

… Michael A. Levin, 7 December, 2011 - 3:41pm