Western White
Pontia occidentalis (Reakirt, 1866)
Family: Pieridae
Subfamily: Pierinae
Identification: Upperside of forewing has marginal markings that are lighter than the submarginal stripe. Below, forewing tip and hindwing have veins outlined with gray-green. Short-day spring and fall forms have more prominent markings.
Wing Span: 1 1/2 - 2 1/8 inches (3.8 - 5.3 cm).
Life History: Males patrol hilltops and ridges for receptive females. Females lay eggs singly on host plants. Caterpillars will feed on leaves but prefer buds, flowers, and fruits. Chrysalids hibernate.
Flight: One flight from June-July in far north; two flights from May-August in the south.
Caterpillar Hosts: Flowers and fruits of various members of the mustard (Brassicaceae) family.
Adult Food: Flower nectar.
Habitat: Mountain peaks, slopes, hilltops, railroad yards, open plains, roadsides.
Range: Alaska south to central California, northern Arizona and northern New Mexico; east to North Dakota and central Ontario.
Conservation: Not usually required.
NCGR: G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.
Management Needs: None noted.
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Verified Sightings
Displaying 1 - 24 of 679 verified sightings
Observation date: Jul 10, 2025
Submitted by: Ed Rothwell
Region: Valley County, Idaho, United States
Verified by: stevekohler
Verified date: Jan 03, 2026
Observation date: Sep 20, 2025
Submitted by: sgguthart
Region: Larimer County, Colorado, United States
Verified by: mikefisher
Verified date: Nov 02, 2025
Observation date: Oct 27, 2025
Submitted by: blgreco
Region: Archuleta County, Colorado, United States
Verified by: mikefisher
Verified date: Nov 02, 2025
Observation date: Jun 26, 2025
Submitted by: bjones7777
Region: Fairbanks North Star, Alaska, United States
Verified by: davidwdroppers
Verified date: Sep 12, 2025
Observation date: Jul 07, 2025
Submitted by: Ed Rothwell
Region: Sweetwater County, Wyoming, United States
Verified by: J_Martineau
Verified date: Sep 05, 2025
Observation date: Jul 04, 2025
Submitted by: NikkiM
Region: Park County, Wyoming, United States
Verified by: J_Martineau
Verified date: Sep 05, 2025
Observation date: Aug 20, 2025
Submitted by: Luna-Linuche.76
Region: Klamath County, Oregon, United States
Verified by: Ken Davenport
Verified date: Aug 30, 2025
Observation date: Jul 17, 2025
Submitted by: Ed Rothwell
Region: Spokane County, Washington, United States
Verified by: davidwdroppers
Verified date: Aug 14, 2025
Observation date: Aug 10, 2025
Submitted by: Luna-Linuche.76
Region: Klamath County, Oregon, United States
Verified by: Ken Davenport
Verified date: Aug 12, 2025
Observation date: Jul 08, 2025
Submitted by: klamke
Region: Scotts Bluff County, Nebraska, United States
Verified by: J_Martineau
Verified date: Aug 08, 2025
Observation date: Sep 21, 2024
Submitted by: LHenriksen
Region: Nez Perce County, Idaho, United States
Verified by: stevekohler
Verified date: Aug 06, 2025
Observation date: Jul 31, 2025
Submitted by: Cascade Colors
Region: Grand County, Colorado, United States
Verified by: mikefisher
Verified date: Aug 03, 2025
Observation date: Jul 10, 2025
Submitted by: Cascade Colors
Region: Grand County, Colorado, United States
Verified by: mikefisher
Verified date: Jul 13, 2025
Observation date: Jul 06, 2025
Submitted by: NikkiM
Region: Carbon County, Montana, United States
Verified by: J_Martineau
Verified date: Jul 08, 2025
Observation date: Sep 02, 2023
Submitted by: Ratty
Region: Saskatchewan, Canada
Verified by: jmgesell
Verified date: Jul 07, 2025
Observation date: Jun 30, 2025
Submitted by: Blue Swallowtail
Region: Adams County, Nebraska, United States
Verified by: Emily Geest
Verified date: Jul 01, 2025
Observation date: Jun 21, 2025
Submitted by: NikkiM
Region: Carbon County, Montana, United States
Verified by: J_Martineau
Verified date: Jun 23, 2025
Observation date: May 19, 2025
Submitted by: MAKI
Region: Lassen County, California, United States
Verified by: Ken Davenport
Verified date: May 27, 2025
Observation date: Jul 15, 2012
Submitted by: RobSimpson
Region: Park County, Wyoming, United States
Verified by: J_Martineau
Verified date: Mar 05, 2025
Observation date: Jun 11, 2024
Submitted by: RobSimpson
Region: Park County, Montana, United States
Verified by: J_Martineau
Verified date: Dec 02, 2024
Observation date: Aug 25, 2024
Submitted by: jrmbutterfly
Region: British Columbia, Canada
Verified by: Paul Prappas
Verified date: Oct 19, 2024
Observation date: Jul 06, 2021
Submitted by: Buddy Mays
Region: Jefferson County, Oregon, United States
Verified by: John Calhoun
Verified date: Oct 07, 2024
Observation date: Aug 22, 2024
Submitted by: jthompson6112
Region: Blaine County, Idaho, United States
Verified by: stevekohler
Verified date: Sep 20, 2024
Observation date: Aug 25, 2024
Submitted by: jrmbutterfly
Region: British Columbia, Canada
Verified by: Paul Prappas
Verified date: Sep 11, 2024
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