Pontia occidentalis occidentalis

Photo Life History:  Pontia occidentalis occidentalis

Habitat:  Urban-Suburban; Agricultural Areas; Valley Wet Meadows; Mountain Canyons; Mountain Hilltops; Arctic Alpine

Host Plants: Descurainia californica; Thlaspi montanum; Isatis tinctoria; Cardaria draba 

Suitable Lab Host Plants: Descurainia pinnata; Descurainia richardsonii; Brassica nigra; Sisymbrium altissimum.  (Almost any mustard will serve in the lab.  Avoid Descurainia sophia.)

Caring for Live Female Butterflies:  Feed females regularly. 

Methods of Female Oviposition:  Portable Cages; Open Screen Cages. (Females can lay many eggs in the lab.)

How to Find Eggs:

How to Hatch Eggs:  Separate eggs individually.

How to Find Caterpillars in the Field:  Look for Caterpillar Strip Patterns. 

Caterpillar setups:  Open Bucket; Twin Cup Method

Larva to Pupa:  Larva Changes Color  (Fifth instars get darker before pupation similar to P. protodice.)

How to Find Pupae in the Field:

Number of Broods per Year: 1-3 broods; depending upon location and altitude.

Overwintering Stage:  Pupa. 

Overwintering Strategies: Your Own Backyard; Refrigerator

Post-Hibernation Strategies: Expose pupae to warmer temperatures, long-day photoperiod, and intermittant humidity (mist spray with water once or twice a day).

Avoiding Diapause Techniques:   Provide larvae with healthy host plant and expose larvae to 24 hours of light. 

Disease Prevention:  Change out host plant and remove frass every five to six using the open bucket method.

Emergence:  Emergence Container

Field Notes: Adults equally at home in disturbed areas of Western cities and towns as they are in Arctic Alpine meadows.  Short-day photoperiod produces early spring form adults.