When I first spotted these beetles I thought they were large hornets. When I got a closer look I saw that they were beetles and there were many of them on some downed brush. The two beetles in this photo were easily the largest. They were very active so I couldn't get a good measurement, but I'd estimate the male was over 20mm and the female 25-30mm. Most of the other beetles looked to be males and were in the 15-20mm range. They were less mobile so much easier to measure. There was one other pair that looked to be in the 20-25mm range. Black beetles, males with white markings on the elytra, females with yellow markings. Both sexes with black and yellow stripes below. Head, thorax and legs covered with white hairs.