Issidae is a family of 'Planthoppers': small insects generally with a stocky body and a not striking, usually brownish body coloration.
The huge number of cross-veins in the wings is very characteristic for Issus coleoptratus.
There is only one similar species, Issus muscaeformis, but this is much more rare.

In my yard, Hilversum, The Netherlands, 3 October 2014