Taken in Marana Az with a Canon Powershot SX10IS
Each spring in April, brightly colored beetles appear in the Sonoran Desert to seek and find proper hosts for their offspring. This is one insect people can’t miss because they appear in huge populations and have a brilliant red head and pronitum, contrasting with mottled yellow slytra marked be a strong black cross. The front looks ant-like and the rear beetle-like. Sometimes as these beetles are running over the hot landscape, they raise their wings and display their black abdomen marked with bright red stripes, making them seem like wasps.
These beetles have a product called cantharidin in their blood, a potential blistering agent, thus the common name. When disturbed their leg joints ooze blood that to a predator may taste bad or be painful. To a human, it may cause mild to severe blistering. Their bright colors advertise this defense.
Iron Cross Blister beetles emerge in April from digger bee nest, usually in loose soils. They feed on spring annuals starting about 11AM to 5PM. After mating, females seek palo verde trees in bud stage, lay eggs at the base of the buds, and then die. The eggs and buds develop together, eggs hatching when the flower opens. Larvae wait in the flowers for the native bees to arrive, hitch a ride back to the nest, where they satay, feeding on the juvenile bee and its provisions. They pupate in the nest and wait for the next spring to emerge as adults