Description ³

While a few probably erroneus older reports may suggest otherwise, Erynnis horatius is a very rare butterfly on Martha's Vineyard. I've only seen three individuals in 25 years of observation. Confusion is mostly likely with E. junvenalis, since both species are large duskywings with strong hyaline spotting on the forewing. Relative to Juvenal's Horace's is more strongly sexually dimorphic, with males often showing little pattern and females showing large hyaline spots and bold patterning, usually appearing as more defined transverse bands on the wing than Juvenal's typically shows. On Horace's, the rear edge of the hind wing generally has a pale band with obvious black spots lined up inside it; on Juvenal's, the pale band is absent or less evident and the black spots are faint or lacking. Unlike Juvenal's, which exhibits just one flight period each year, Horace's has two flight periods, in late spring and then in midsummer. So any "Juvenal's" seen after about the end of June should be carefully scrutinized as a potential Horace's. Distribution of Horace's and Juvenal's probably overlaps on the Vineyard, since both use tree oaks and possible scrub oak as their larval host plants.

Sources and Credits

1. (c) Katja Schulz, some rights reserved (CC BY), http://www.flickr.com/photos/86548370@N00/4800577641
2. (c) Matt Pelikan, some rights reserved (CC BY), uploaded by Matt Pelikan
3. Adapted by Matt Pelikan from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Erynnis_horatius

More Info

• iNat taxon page
• Animal Diversity Web
• Biodiversity Heritage Library
• BOLD Systems BIN search
• BugGuide
• Butterflies and Moths of North America
• CUIC Insect Images
• Global Biodiversity Information Facility (GBIF)
• HOSTS - a Database of the World's Lepidopteran Hostplants
• Maryland Biodiversity Project
• Maryland Moths
• Mass Moths
• Moth Photographers Group
• Moths of North Carolina
• NatureServe Explorer 2.0
• Pacific Northwest Moths

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