Wedge-shaped Beetle

Ripiphorus sexdens

Coleoptera: Rhipiphoridae

These beetles are phoretic parasitoids, like certain meloid beetles.  Females lay eggs into flowers and the hatchlings, called triungulins, then hitch a ride with visiting solitary bees.  Carried to the bees' nest, they become internal parasites of the host larvae. Eggs are laid on buds that will soon bloom. Apparently, the idea is to have the young ready to fly off to their new "families" as soon as the flower is ready for the bees' visits. (Text by Hartmut Wisch and Ron Hemberger).

The elytra (forewings) are reduced to nubs, exposing the hindwings in these unusual beetles

The male beetle is the one with the elaborate red antennae. Both beetles were found together, but weren 't mating when discovered. A nesting site of Diadasia bees was a few feet away. Flowers abundant in the area included a bit of encelia, bindweed, and lots of mallow. I suspect the Diadasia are mallow visitors....Ron Hemberger.