I found this interesting information on the use of Gulf Coast Swallow-wort by Monarchs during March-April in SC.http://akdavis.myweb.uga.edu/DavisPubli ... 202010.pdf
Biological Observations of Monarch Butterfly Behavior at a Migratory Stopover Site: Results from a Long-term Tagging Study in Coastal South Carolina
John W. McCord & Andrew K. Davis
Page 9, "Overwintering Monarchs" second paragraph, sentence 10-12.
"However, JWM has made numerous observations of monarchs ovipositing on swallow-wort (Seutera angustifolia) [Cynanchum angustifolium] in transitional upland habitats adjacent to tidal saltmarsh within the central South Carolina coastal zone."http://plants.usda.gov/java/profile?symbol=CYAN5
Cynanchum angustifolium Pers. gulf coast swallow-wort
This plant is also used by Queens:http://www.coastalwildscapes.org/2011/b ... low-worts/