New York Natural Heritage Program
Regal Moth
Citheronia regalis (Fabricius, 1793)

Threats [-]
Two main threats led to the extirpation of the regal moth from New York State: chemical spraying to control gypsy moths, and the gypsy moth biocontrol fly Compsilura concinnata. Most Lepidoptera are negatively impacted by the chemicals used in gypsy moth sprays, and historically the use of these chemicals lead to the extirpation of the regal moth (Butler et al. 1995, NatureServe 2017). Compsilura concinnata was introduced as a way to control gypsy moth populations in the United States in 1906, but was found also to parasitize moths of Saturniidae as well as other native species. It is believed that C. concinnata is one of the reasons that regal moths had difficulty recovering after spraying when DDT was discontinued (NatureServe 2017). It is also suspected by some Lepidopterists that regal moths are negatively affected by artificial light.

Conservation Strategies and Management Practices [-]
This species is sensitive to chemical spraying (e.g., with Dimilin), and so broadcast use of these chemicals in their habitat should be avoided (NatureServe 2017). If chemical spraying is necessary to eradicate target species (e.g., gypsy moths), Bacillus thuringiensis (Btk) is an alternative. Btk is used in the spring to target gypsy moth caterpillars, and it does not persist in the environment long enough to significantly impact summer feeding caterpillar species, such as regal moth caterpillars (Schweitzer et al. 2011). Two other gypsy moth biocontrols that appear to be very effective at eliminating gypsy moths without impacting non-target species, yet are not currently available commercially, are Gypchek (a viral preparation) and Entomophaga maimaiga (a fungus). It is also possible this species is negatively impacted by artificial lighting, and so steps should be taken to minimize lighting at night. Any necessary artificial lighting should use lamps that emit yellow or red light, because these have a lower impact on moth species (Schweitzer et al. 2011). The lamps that have the least effect on moth populations are low pressure sodium lamps, and these should be used whenever possible.

Research Needs [-]
One of the most important research needs for this species is more current and complete data regarding species status and distribution. Regal moth populations would benefit from statewide survey and monitoring efforts in suitable habitat.