Decline of the Ailanthus Webworm Moth after Invasion by the Spotted Lanternfly

Kenneth D. Frank*

*2508 Pine Street, Philadelphia, PA 19103.

Northeastern Naturalist, Volume 32, Issue 2 (2025): 225–241

First published early online: 24 May 2025

Abstract
Lycorma delicatula (Spotted Lanternfly) is a polyphagous, phloem-feeding insect that first appeared in North America in Pennsylvania in 2014. The insect’s preferred host plant is Ailanthus altissima (Tree-of-heaven), a non-native weedy tree. In temperate North America, Tree-of-heaven is the sole effective host plant of larvae of Atteva aurea (Ailanthus Webworm Moth), a neotropical native that has naturalized on Tree-of-heaven. To assess how invasion by the Spotted Lanternfly impacted the Ailanthus Webworm Moth, I compiled from the community science platform iNaturalist.org. more than 400,000 observational records from 7 Mid-Atlantic states including 26 invaded counties (defined herein as ≥20 reported observations of Spotted Lanternfly in a year) and 250 uninvaded counties (less than 5 reported observations in a year). My analysis investigated the ratio of observations of the Ailanthus Webworm Moth in invaded counties compared to uninvaded counties. The results showed this ratio declined from 1.15 to 0.31 during the period before and after invasion by the Spotted Lanternfly. In addition, I investigated Ailanthus Webworm Moth observations as a proportion of observations of all Lepidoptera. In invaded counties during the same time frame, this proportion declined from 0.013 to 0.004; by contrast, the proportion did not decline in counties where the Spotted Lanternfly had not invaded. These findings demonstrate a decline in abundance of the Ailanthus Webworm Moth in counties where Spotted Lanternfly had invaded compared to those it had not invaded. The Spotted Lanternfly invasion or human intervention to control it, or both, likely reduced abundance of the Ailanthus Webworm Moth.

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