On Oct 24, 2006, bonitin from Gent Belgium (Zone 8a) wrote:
Trichius fasciatus can be distinguished from the closely related Trichius rosaceus by the white hairs on the sides of the thorax and the rear of the abdomen while T.rosaceus has them more reddish-orange tinged like the specie name suggests.
On Dec 14, 2009, Zaragoza from Zaragoza Spain (Zone 8b) wrote:
Also help the spots of the basis of the elytra. This is a variable character but usually T. rosaceus have two separated humeral spots and T. fasciatus have an entire black band in all the basis of the elytra.
The most definitely character is in the middle-tibiae I think.