Code for Statistical Analyses

Widespread declines in the abundance of insects portend ill-fated futures for their host ecosystems, all of which require their services to function. For many such reports, human activities have directly and significantly altered the land or water of these ecosystems, raising questions how insects in less impacted environments are faring. I quantified the abundance of flying insects during 15 seasons over a 20-yr span on a relatively unscathed, subalpine meadow in Colorado, where weather data have been recorded for 38 yr. I discovered that insect abundance declined an average of 6.6% annually, yielding a 72.4% decline over 20 yr. Information theoretic analysis of 59 combinations of weather-related factors best supported the association between abundance and an interaction between date and mean daily temperature the prior summer. Specifically, a seasonal increase in abundance tended to a seasonal decline as the previous summer’s mean daily temperature increased, resulting in a long-term decline as mean daily temperature-minima during summer have risen here 0.8°C per decade. In this relatively pristine area, insects are declining precipitously, auguring poorly for this and possibly other such ecosystems that depend on the roles insects play in food webs, pollination, pest control, and nutrient cycling.