A paper wasp, Polistes comanchus
is about to chase a cactus fly, Odontoloxozus longicornis
, away from a wounded Baccharis sarothroides
branch oozing delicious sap. The flower scarab, Euphoria leucographa
, will hunker down and stand its ground as the wasp tries to monopolize the feeding spot. Molino Basin, Santa Catalina Mountains, Pima County, Arizona. USA. 27 October 2007.