Keltonia tuckeri.
Size: approx. 3 mm. Photo: 09/10/11, 6 pm.

This tiny plant bug is Keltonia tuckeri. There is a bit of a question mark behind the species identification because I couldn't find photos of the other species.  
bug guide (this photo):
L. A. Kelton, The Canad. Entomol., 96, 668, 1966: