Table 1.

Records used in this study

Data source	Plants			Insects
	Asclepias records	A. syriaca records (1950 to 2006)	Total plant records (1950 to 2006)	D. plexippus records	Total lepidoptera records
Global Biodiversity Information Facility	14,458	627	1,264,715 (452,073)
Consortium of Midwest Herbaria	21,458	1,251	3,208,245 (1,065,608)
Online Virtual Flora of Wisconsin	2,496	384	362,789 (288,291)
Minnesota Biodiversity Atlas	1,098	93	144,254 (98,919)
Total	39,510	2,355	4,980,003 (1,904,891)
Symbiota Collections of Arthropods Network				1,191	323,611

For each plant data source, we downloaded all available records as of March 2018. For insects, we downloaded all records matching a higher taxonomy search for “Lepidoptera” as of April 2018. In both cases, we then filtered records to produce these sample sizes. For Asclepias, we provide the number of records for all Asclepias in the eastern United States from 1900 to 2016 (used in the analyses presented in Figs. 1 and 2 and SI Appendix, Fig. S6), as well as the number of records of A. syriaca used for multimodel inference (i.e., those records from 1950 to 2006 collected in the regions shown in SI Appendix, Fig. S9). The first number for total plant records is the number of records 1900 to 2016; the value in parentheses is the number of records used in multimodel inference.