Page 127 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Pieridae
DISTRIBUTION Western North America, from Alaska to New Mexico
HABITAT Montane slopes, meadows, canyons, shrub-steppe, desert washes,
and beaches
HOST PLANTS Rockcress (Arabis spp.), tansymustards (Descurainia spp.),
and Tumble Mustard (Sisymbrium altissimum)
NOTE Caterpillar with a pupal period lasting 10 to 11 months
CONSERVATION STATUS Not evaluated, although the US Fish and Wildlife Service lists
subspecies insulana as a species of concern

ADULT WINGSPAN
1⁹∕₁₆–1¾ in (40–45 mm)
CATERPILLAR LENGTH
1³∕₁₆–1³∕₈ in (30–35 mm)
EUCHLOE AUSONIDES
LARGE MARBLE 125

(LUCAS, 1852)

Large Marble caterpillars emerge from eggs that are laid singly
on unopened buds of cruciferous host plants. Early instar larvae
station themselves vertically among flower clusters to feed on

buds and flowers, and cover this part of the plant with loosely

spun silk. The caterpillars do not make nests. Later instars move
on to leaves and seedpods. The larvae are usually solitary with
only one per host plant. Prior to pupation, they become purplish
and wander in search of a suitable pupation site.

Development from egg hatch through five instars to pupation
takes roughly three weeks. The pupa oversummers and
overwinters, spending 10 to 11 months in this stage. Survival
appears to depend on camouflage. However, minute pirate bugs

(Anthocoridae) common on crucifers probably kill many of the
larvae, and parasitic wasps parasitize late instars and also pupae.
Other closely related Euchloe species occur in North America
and Europe. The Large Marble caterpillar is yellow with
broad, purple-gray, longitudinal stripes. The body
is covered with large, black spots, each bearing
a single seta. There is a bold, white ventrolateral
stripe bordered below with a broken, yellow line.
The head is gray with black spots, and the legs
and claspers are also gray.

Actual size