How far away do weak light traps attract moths?

Details

Moths are frequently used as indicators of biodiversity or habitat quality. Light traps are the most effective and widely used method for collecting data on moth communities, so knowing how far away they attract moths is essential for interpreting those data ecologically.

Researchers conducted two community-wide mark-release-recapture experiments in forest habitats in central Europe. They tested whether the percentage of marked moths recaptured at weak artificial light sources—two 15 W UV-light tubes—depended on their release distance. In total, 2,331 moths from 167 species were caught at light traps and released 2–100 m away. Of these, 313 returned to the light trap within 5 minutes of release.

Recapture was generally low, with a gross rate of 13.4%, and decreased strongly as release distance increased. Ambient temperature and moth sex did not significantly affect the percentage recaptured. Only in the Geometroidea was recapture slightly greater for larger species. There were no significant differences between moth superfamilies in how their attraction to light depended on distance.

The researchers concluded that the attraction radius of low-powered light traps is very small, often below 10 m. They therefore considered moths good indicators of habitat quality and fragmentation because moths are rarely attracted to such traps from distant habitats.