Based on 4,897 research-grade iNaturalist observations in Oregon, California Tortoiseshell is most often recorded in July; in Oregon it behaves like a summer visitor / breeder. It ranks #1 among butterflies recorded in the state in our data.
Nymphalis californica
California Tortoiseshell in Oregon 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 Oregon in July
Western Tiger Swallowtail
Lorquin's Admiral
Snowberry Checkerspot
Gray Hairstreak
Clodius Parnassian
Woodland Skipper
Painted Lady
Small White
Places to look in Oregon
National ForestWillamette National Forest
National ForestMount Hood National Forest
National ForestDeschutes National Forest
Botanical GardenHoyt Arboretum
Botanical GardenLeach Botanical Garden
National ForestUmatilla National Forest
FAQ
When does California Tortoiseshell appear in Oregon?
Mainly June–September, with the most records in July.
How common is California Tortoiseshell in Oregon?
It ranks #1 by number of iNaturalist observations among butterflies in Oregon (4,897 records in our sample).