Based on 3,182 research-grade iNaturalist observations in Illinois, Orange Sulphur is most often recorded in September; in Illinois it behaves like a summer visitor / breeder. It ranks #12 among butterflies recorded in the state in our data.
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Orange Sulphur in Illinois 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 Illinois in September
Monarch
Painted Lady
Common Buckeye
Fiery Skipper
Silver-spotted Skipper
Black Swallowtail
Pearl Crescent
Small White
Places to look in Illinois
State ParkCahokia
Botanical GardenMorton Arboretum
National ForestShawnee National Forest
Botanical GardenChicago Botanic Garden
Botanical GardenLadd Arboretum
State ParkStarved Rock State Park
FAQ
When does Orange Sulphur appear in Illinois?
Mainly July–October, with the most records in September.
How common is Orange Sulphur in Illinois?
It ranks #12 by number of iNaturalist observations among butterflies in Illinois (3,182 records in our sample).