Observations on sex ratio and phenology in Danae testacea (Ziegler), a cantharidin-orienting handsome fungus beetle (Coleoptera: Endomychidae)

Cantharidin – “Spanish fly” – is a terpenoid produced by blister beetles (Meloidae) and false blister beetles (Oedemeridae) for defensive purposes.  A number of insect species are attracted to this compound in nature, but the specific role of cantharidin in their biology is unknown. Five species of Endomychidae exhibit this cantharidin-orienting behavior, including the little known handsome fungus beetle Danae testacea (Ziegler).  Using D. testacea specimens (> 2000) collected from cantharidin baited jar traps in 1992 at two main localities in Southern Wisconsin, we have begun to determine the phenological basis of sex ratio patterns. These data will be used to further understand what role sex might have with cantharidin-orienting behavior and to expand our knowledge of natural history of these relatively unknown beetles.