A field investigation of Depressaria (Elachistidae) host plants and ecology in the Western United States


Depressaria Haworth is a relatively species-rich group of moths with a Holarctic distribution. In western North America there has been a striking radiation of Apiaceae-feeding members of the genus. To understand patterns of Depressaria distribution, host usage, and natural history in the western United States, we surveyed select potential host plants for larvae. Particular emphasis was placed on surveying plants in the genus Lomatium Raf. because most published Depressaria host plant records are from this genus. Surveys took place throughout the western United States from Utah and Wyoming to the Pacific Ocean, and from the Canadian border in Washington State to California and northern Arizona. Approximately 32,000 km of roadway were covered. When larvae were encountered they were collected and reared to adulthood. Ten species of Depressaria were reared. Two additional potentially undescribed species, represented only by female specimens, were also reared. Our data support previously published accounts of Depressaria biology, host usage, and distribution, consistent with the fact that known host plant genera were targeted in the surveys. Substantial changes in land use have occured in some parts of the western United States since the work of J. F. G. Clarke, an early student of Depressaria. Several of his published collection localities, including the type locality for D. whitmani Clarke and most collection localities near the Pacific Coast and in dry grasslands, have been destroyed or seriously degraded by agriculture, grazing, roadway improvements, and other forms of development.

Publication Title

Journal of the Lepidopterists' Society

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