Page 66 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Papilionidae
DISTRIBUTION Western North America, from Alaska to New Mexico
HABITAT Mountains, upper elevations to highest Arctic-alpine
HOST PLANTS Stonecrop (Sedum spp.)
NOTE Aposematic caterpillar that emits a foul odor when disturbed
CONSERVATION STATUS Not evaluated, but common within its range

ADULT WINGSPAN
2⅜–2⁹∕₁₆ in (60–65 mm)
CATERPILLAR LENGTH
1³∕₁₆ in (30 mm)
PARNASSIUS SMINTHEUS
MOUNTAIN PARNASSIAN
64
DOUBLEDAY, [1847]

Mountain Parnassian females lay their eggs singly on and around
stonecrop plants. The eggs overwinter and the caterpillars
hatch in late spring but do not consume their eggshells. The
caterpillars, which are solitary, bask openly in sunshine but feed
nocturnally, primarily on leaf tips. No nests are made. The larvae
are easily found by searching patches of Sedum in mountainous
areas. When disturbed, the caterpillars twitch violently, drop to
the ground seeking cover, and may emit a bad-smelling chemical
from their yellow osmeterium. Their aposematic coloration also
suggests they may be toxic.

Caterpillar development is slow, taking 10 to 12 weeks. There are

five instars, and pupation occurs in a loose cocoon constructed
among ground debris. The flight period of the adult—a mostly

white butterfly with some red spots and dark markings—is late

May to early September depending on latitude and elevation.
Other Parnassius species occur in North America and Eurasia,
all confined to mountainous habitats.

The Mountain Parnassian caterpillar is jet black
with bristly setae and four rows of contrasting
yellow-gold spots that develop in intensity as the
caterpillar matures. The lateral row of spots has
two per segment (except segments one to three,
with a single spot per segment), a larger spot
anteriorly, and a smaller one posteriorly.
Actual size