River bugs?

I guess I should have been more detailed, they make their on shell out of sand and look kind of like a spider/crab but with no claws.

they crawl on the rocks and river bottom. I looked up periwinkle and al I got was info on the flowers.

River bugs?
They could be caddisfly larvae.



Caddisfly larvae will gather up bits of rock, wood, vegetation and/or snail shells and web them together with silk to form a protective structure for themselves, covering their body and which they can retract into. They carry this protective 'shell' around with them, so often only the very front of their body is visible. There are a variety of different shapes that the caddisflies can build their case. Some will make straight tubes, some species make their in spirals or curled up like snail shells.



They are common in many freshwater lakes, ponds and rivers.



Caddisflies are in the insect order Trichoptera, and are actually rather closely related to the butterflies and moths (Lepidoptera). The larva itself looks rather like a caterpillar if it can be removed from it's protective home. The adults do not live underwater, but look rather like extraordinarily dull moths with very long antennae.



Here's some links that include some pictures:



http://www.bugsurvey.nsw.gov.au/html/pop...

http://bugguide.net/node/view/14964

http://www.cirrusimage.com/Trichoptera_c...
Reply:i think they could be crabs without claws

Just kidded

sorry no idea
Reply:Haysoos is right