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.
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