Friday 17 February 2012: Nobody home any more
These are the exoskeletons of cicadas.
Immature Cicada nymphs live underground where they suck sap from the roots of trees and shrubs. When they approach maturity, they dig to the surface (hence the claw like front feet) and molt into winged adults, leaving the exoskeleton behind. The winged adults live for a very short time, mate and die. The nymphs live underground for years until they are mature enough to emerge.
At the moment there are lots of them on the trees, and the adults are making their easily recognizable noise, really a sound of summer.