Spatiotemporal Patterns of Large Moth Activity Across Forest-Grassland Habitat Complexes in Central Illinois
Large moths are known to serve key roles in many ecosystems as herbivores, pollinators, and prey to diverse species. Nocturnal plants and animals that depend on moths often have narrow diel and seasonal activity windows due to restrictions such as cooler nighttime temperatures and limited light availability. Because of these limitations, increasingly well-documented declines in moths and species such as the Eastern Whip-poor-will (Antrostomus vociferus), a specialist moth predator, have raised concerns about potential mismatches in activity between moths and the taxa that rely on them for food or pollination.
Since 2021, we have been working to investigate large moth activity in Midwestern landscapes by conducting hundreds of hours of insect trapping using ultraviolet-light bucket traps on whip-poor-will breeding grounds in central Illinois. We distributed trapping efforts throughout the summer across forest and edge habitats and lit traps during one of three 90-minute time blocks (dusk, solar midnight, and dawn). Moths with a body length ≥ 10 mm were sorted out of these samples, counted, and massed to determine patterns and drivers of large moth activity on the landscape. Large moth abundance and biomass increased in forest interiors relative to forest/grassland edges and generally peaked in late June relative to the rest of the season, with those peaks largely driven by forests. Relative to solar midnight and dawn, moth abundance and biomass were highest after dusk, particularly in forests. Moth captures also differed between field sites and showed complex responses to interactions involving temperature, moon brightness, relative humidity, and wind speed. These insights into the spatiotemporal activity patterns of large moths highlight potential opportunities for the conservation of this important nocturnal group and species that depend on them for survival.
