Goldenrod Soldier Beetle

Chauliognathus pensylvanicus — the goldenrod soldier beetle, sometimes called the Pennsylvania leatherwing — is one of about 5,000 species in family Cantharidae (the soldier beetles, also called leatherwings for the soft leathery elytra). Adults are 9-12 mm long with bright yellow elytra carrying two dark spots and a distinctive black band across the rear. The species is one of the most-encountered late-summer beneficial insects in eastern and central North American gardens, parks, and meadows. Adults emerge in mid-to-late summer and aggregate by the hundreds on flowering goldenrod (Solidago) and other late-season composites. The aggregations are simultaneously pollinator congregations (the beetles transfer pollen between flowers as they walk and feed) and predator congregations (the beetles eat aphids, small caterpillars, fruit fly larvae, and other small soft-bodied insects on the same plants). The combination makes goldenrod soldier beetle one of the most ecologically valuable garden insects: she pollinates flowers, controls pest aphids, and provides food for spiders, wasps, and small vertebrate predators in turn. Defense: like blister beetles (the closely related family Meloidae), soldier beetles produce cantharidin in defensive glands — providing protection against most vertebrate predators, who learn to avoid the bitter, toxic compound. Larvae are equally beneficial: soft-bodied dark velvet predators that hunt slugs, snails, root maggots, fly pupae, and other soil-dwelling soft pests in garden soil and leaf litter. The species is the most-cited 'flagship beneficial' garden beetle in popular pollinator-conservation literature alongside ladybugs and parasitoid wasps.