Based on 1,276 research-grade iNaturalist observations in Indiana, Hackberry Emperor is most often recorded in August; in Indiana it behaves like a summer visitor / breeder. It ranks #11 among butterflies recorded in the state in our data.
Asterocampa celtis
Hackberry Emperor in Indiana by month
Bars show research-grade observations per month. They mix true seasonality with how often people are outdoors, so treat small numbers with caution.
Also seen in Indiana in August

Monarch

Eastern Tiger Swallowtail

Silver-spotted Skipper

Common Buckeye

Black Swallowtail

Spicebush Swallowtail

Zabulon Skipper

Pearl Crescent
Places to look in Indiana
Turkey Run State Park
Brown County State Park
Prophetstown State Park
National ForestHoosier National Forest
Mounds State Park
Falls of the Ohio State Park
FAQ
When does Hackberry Emperor appear in Indiana?
Mainly June–August, with the most records in August.
How common is Hackberry Emperor in Indiana?
It ranks #11 by number of iNaturalist observations among butterflies in Indiana (1,276 records in our sample).