Erynnis horatius
In 3 days ~30% in a week ~50%
Erynnis horatius, commonly known as Horace's duskywing, is a species of butterfly in the family Hesperiidae. It is found in the United States from Massachusetts to Florida, and west to eastern South Dakota, the Gulf Coast, south-eastern Utah, Colorado, north-eastern Arizona, and New Mexico. It is listed as a species of special concern in the US state of Connecticut.
Fringes are brown. Upperside of male forewing is dark brown with little contrast and no white overscaling. Upperside of female forewing is light brown with a contrasting pattern and large transparent spots. Underside of hindwing is usually without two spots below the apex. The male has a costal fold containing yellow scent scales; the female has a patch of scent scales on the 7th abdominal segment. The wingspan is 36–49 mm.
There are two generations in the north, with adults on the wing from April to September; there are three generations in the deep south and Texas, with adults on the wing from January to November. Adults prefer open woodlands and edges, clearings, fence rows, wooded swamps, power-line right-of-ways, open fields and roadsides.
Caterpillars are hosted by various oak species such as willow oak (Quercus phellos), northern red oak (Q. velutina), scrub oak (Q. ilicifolia), water oak (Q. nigra), post oak (Q. stellata), and live oak (Q. virginiana). Adults consume nectar from flowers up to about 4.5 feet (1.4 m) above ground level, including those of dogbane, buttonbush, sneezeweed, goldenrod, peppermint, boneset, and winter cress. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Congaree National Park | 🇺🇸 United States | |
| 2 | Merritt Island National Wildlife Refuge | 🇺🇸 United States | |
| 3 | Shenandoah National Park | 🇺🇸 United States | |
| 4 | Great Smoky Mountains National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Miami | 🇺🇸 United States | |
| 2 | San Antonio | 🇺🇸 United States | |
| 3 | Austin | 🇺🇸 United States | |
| 4 | Orlando | 🇺🇸 United States | |
| 5 | Dallas | 🇺🇸 United States | |
| 6 | Houston | 🇺🇸 United States | |
| 7 | Washington | 🇺🇸 United States | |
| 8 | Baltimore | 🇺🇸 United States | |
| 9 | Philadelphia | 🇺🇸 United States | |
| 10 | New York City | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Horace's Duskywing sighting in Shenandoah National Park on a given day, based on 26 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 138th most-seen of the 723 insects we can rate there. Over three days the chance rises to about 30%, and over a week to about 50%, if each day is a fresh chance.
September
In that month about 20% of wildlife watchers report a Horace's Duskywing in Shenandoah National Park on a given day, against under 5% in November to June, the lowest months.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Horace's Duskywing sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
3rd of 4
Of the 4 parks where we can rate Horace's Duskywing sightings, Shenandoah National Park ranks 3rd at about 10%. The best odds are in Congaree National Park (United States, about 20%) and Merritt Island National Wildlife Refuge (United States, about 10%).
Same genus: Erynnis
The closest relatives of the Horace's Duskywing that you can see in Shenandoah National Park (genus Erynnis, Duskywings) are Juvenal's Duskywing (about 10%), Sleepy Duskywing (about 10%) and Dreamy Duskywing (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Horace's Duskywing is recorded against all the insects logged in Shenandoah National Park (26 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
