Occasionally, we find some very strange looking bees. These two series of photos are both of long-horned bees in the genus Melissodes that I asked Brian Lobbes to image. However, something is distinctly odd about their faces. Male long-horned bees usually have yellow faces and long antennae (hence their common name); but both of these bees have half yellow faces and one long antenna. In fact they are both male and female, or gynandromorphs. Gynandromorphy typically arises from a problem with chromosome segregation during mitosis and can lead to the organism having some cells that become male and other cells that become female. In the top specimen, the bee appears to be mostly female, with hairy legs to collect pollen but the right side of the face and antenna are male. In the lower specimen, the body is more male, lacking those bushy leg hairs, and with alternating female patches on the face: a dark right mandible, dark left face, and short (female) right antenna. So cool!
I am a Postdoctoral Associate at CU-Boulder and have lead a number of projects studying patterns of native bee diversity in Colorado. Please enjoy your visit and contact me if you have any questions.