Machimus atricapillus - side basking, Heeswijk-Dinther, Netherlands

This robberfly is basking on this log, yet in a weird angle. It's practically laying on its side, although hard to see in this photo. Ignorant me wished it would sit straight instead, but by chance I've found out this is a key behavior of this robberfly species, and one way to tell it apart from others. A second example:

Another obscure detail is visible in the photo. Only the thigh of the frontal leg lacks the thick black bristles found on the rest of the legs.