Historic specimens of two re-emerging western flatheaded borer pests provide a foundation for future research

Chrysobothris mali Horn and Chrysobothris femorata Olivier are economically important flatheaded borers that feed on a complex of woody deciduous plants including fruit, nut, and shade trees. Chrysobothris femorata is widely distributed across North America, while C. mali is only reported west of the Rocky Mountains. In Oregon, the two species coexist and losses of up to 30% of trees have recently been documented in establishing hazelnut orchards. Young trees can be highly susceptible to girdling by the larvae. There is a notable lack of information on phenology, host use and distribution of these species in the west.  To lay the groundwork for future work with these species, label data and morphological measurements were collected from 346 C. femorata and 256 C. mali specimens residing in major regional entomology collections including the Oregon State Arthropod Collection (OSAC) at Oregon State University, the M.T. James Museum at Washington State University, the William F. Barr Entomological Museum at University of Idaho. The data collected from these institutions was also combined with the online specimen databases from the California Academy of Sciences, bringing the total number of specimens to 404 C. femorata and 527 C. mali.  The resulting database was used to produce a list of the common native host plants utilized by these species as well as distributional maps and flight periods for both species. This data forms a foundation for better understanding the biology of these understudied, yet economically impactful, re-emerging pests.