Data from: Precipitation drives the abundance and distribution of Arctia virginalis: A 40-year study

Ecology seeks to understand the abundance and distribution of species.
Ecologists typically collect either long-time series without knowledge of
the drivers or short-term experimental results, which may not scale up. We
surveyed the annual population dynamics of Arctia virginalis for 40 years
and conducted experiments examining the relative roles of abiotic
conditions, host plants, predation, parasitoids, and viral infection.
Rather than finding a single limiting factor, these factors were all
important at some times or places. Annual densities varied by 1000-fold
and showed evidence of a regime shift around 2002, coincident with
changing precipitation. Wet sites and wet years supported higher
densities, and precipitation interacted with most of the factors
considered. Population control was context-dependent, but water
availability was generally the relevant context. Precipitation appears to
be important for other Lepidoptera in western North America. Studies that
include experimental tests of population drivers are required to
effectively manage insect populations.