A male Pacific Spiketail, Cordulegaster dorsalis, has caught and is devouring a yellow jacket wasp.

Males of this large dragonfly species cruise the foothills of the Santa Cruz Mtns hunting yellow-jackets, on which they appear to prey exclusively. The location here is a lower elevation near a stream; usually I find them higher, especially in chaparral areas.

Sometimes another member of the prey's social group shows up (summoned, apparently, by an alarm pheromone) but can do nothing to influence the outcome. That happened in this case (see link); the odo acted mildly annoyed by the second wasp's harassment, but not enough to fly away until the prey was consumed; in fact, it seized and consumed another immediately after finishing this one, but I cannot say with certainty that victim #2 was this harasser.

Prey appears to be a Vespula sp.