Pale Swallowtail
Papilio rutulus
Large butterfly with black wings, white band across forewings, and blue-spotted cream hindwings. Males perch on hilltops or patrolling low. Caterpillars feed on sycamore, willow, and other native trees.
Plants that support Pale Swallowtail
39 plants
American Cow-parsnip
Heracleum maximum
perennial herb
Caterpillars feed on umbelliferous plants; generations May-Aug
Arroyo Willow
Salix lasiolepis
shrub
Primary host plant for larval development; multiple broods spring-summer
Bitter Cherry
Prunus emarginata
tree
Early larval host plant; supports spring generation
Bog Lupine
Lupinus polyphyllus
perennial herb
spring through early summer nectar visitor
Bog Orchid
Platanthera dilatata
perennial herb
Adult foraging during flight season
California Alder
Alnus rhombifolia
tree
larval food plant for caterpillars in California riparian zones
California Buckeye
Aesculus californica
tree
Spring flight period nectar foraging, May-Jun
California Coffeeberry
Frangula californica
shrub
Documented larval host, caterpillars feed on foliage in spring-early summer
California Live-oak
Quercus chrysolepis
tree
Larval host plant; caterpillars feed on new oak leaves Apr-Jul
California Manroot
Marah fabacea
vine
Larvae feed on vine foliage in spring through early summer
California Sycamore
Platanus racemosa
tree
Primary larval host plant; caterpillars feed on young foliage April-July
Chaparral Mallow
Malacothamnus fasciculatus
shrub
Spring and summer adult foraging
Coast Larkspur
Delphinium decorum subsp. decorum
annual
Adult nectar source mid-summer
Coyote Willow
Salix exigua var. hindsiana
tree
Important early-season caterpillar host for first generation
Douglas's False Willow
Baccharis glutinosa
perennial herb
mid-to-late summer nectaring
Hollyleaf Buckthorn
Rhamnus crocea
shrub
Primary larval host plant in California chaparral and oak woodlands
Hollyleaf cherry
Prunus ilicifolia
tree
larvae feed on foliage April-August, multiple generations
Leopard Lily
Lilium pardalinum subsp. pardalinum
geophyte
Caterpillars feed on lily foliage during larval development April-July
Monkeyflower (Scarlet)
Erythranthe cardinalis
perennial herb
Adult nectar foraging during warm months; multi-generational broods use as food source
Mountain Coyote Mint
Monardella odoratissima
perennial herb
Summer emergence and breeding; multiple generations May-September
Mulefat
Baccharis salicifolia
shrub
Adult butterflies feed on nectar during breeding season
Ninebark
Physocarpus capitatus
shrub
Larval host plant; caterpillars feed on ninebark foliage
Nootka Rose
Rosa nutkana
perennial herb
Spring adult emergence and feeding
Pacific Pea
Lathyrus vestitus var. vestitus
vine
Larvae occasionally feed on Lathyrus foliage
Pacific Willow
Salix lasiandra var. lasiandra
shrub
Preferred larval host plant for multiple generations May-September
Royal Larkspur
Delphinium variegatum subsp. variegatum
perennial herb
Primary larval host plant for spring brood development
Scarlet Bugler
Penstemon centranthifolius
perennial herb
early spring adult nectar source
Scouler's Willow
Salix scouleriana
shrub
Visits catkins and flowers
Showy milkweed
Asclepias speciosa
perennial herb
Visits flowers for nectar during adult foraging; multiple generations utilize milkweed as fuel source
Sierra False Bindweed
Calystegia malacophylla subsp. Pedicellata
perennial herb
spring through early summer adult feeding
Southern Humboldt Lily
Lilium humboldtii var. ocellatum
perennial herb
Larvae feed on lily foliage during growing season, multiple generations Mar-Aug
Western Azalea
Rhododendron occidentale
shrub
Larval host plant, caterpillars feed on foliage April-June
Western Columbine
Aquilegia formosa
perennial herb
Spring generation adults; early season nectar source Apr-Jun
Whitehead Mule-ears
Wyethia helenioides
perennial herb
Host plant for larval development; caterpillars feed on foliage in spring months
Yellow Coastal Bush Lupine
Lupinus arboreus
perennial herb
Spring adult foraging
Yerba Santa
Eriodictyon californicum
shrub
Adult nectar source during May-July bloom