Blister Beetle (Meloidae)
probably in genus Cysteodemus
The blister beetles (family: Meloidae, order: Coleoptera) are elongate and narrow with soft and flexible wing covers (elytra). Many of the common species contain cantharadin (Spanish-fly), a substance that will cause blisters when applied to the skin. The beetles use this and related analogs as defensive compounds against larger herbivores that soon learn not to browse flowers with these distinctive beetles (often irridescent green, blue or other bright color such as golden or shiny black). Lytta vesicatoria (L.), a common European species has been used to obtain Spanish-fly, which reputedly irritates and stimulates the sexual organs and was thought to be an aphrodisiac. In the genus Meloe, the adults are called oil beetles because they can exude an oily fluid from the joints of their legs when disturbed, in order to defend against predators, both insect and vertebrate. Several species of blister beetles are pests of potatoes, tomatoes and other plants. However, the larvae of most blister beetles are beneficial since they feed on grasshopper eggs. But a few species live in bee nests where they feed on the eggs and food stored in the cells. The smallest larvae (first instar) of many species are peculiar (compared to most beetles) in that they have long running legs to aid them in their search for eggs, later instars are typical of most beetles since they look like fat grubs with short stubby legs. Image (C) 1995 by John A. Byers.

More recent photos:
Arizona I
Arizona II
Utah
Colorado