According to my old Arnett and Jacques Insect Guide, which lists this species, there is variation in color from red to yellow markings. I occassionally see the yellow type represented here in BugGuide, but the red is by far dominant in my gardens. Here is an image of one. They are very common in June, often hitching a ride on the cut flowers that we bring to farmers' markets. This is probably because we have plenty of their larval hosts - ground nesting bees and wasps.