Page 139 - 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 northwest Canada to
southern California
HABITAT Rocky desert steppe, subalpine ridges, hills, and canyons
HOST PLANTS Rock cress (Arabis spp.), tansymustard (Descurainia spp.),
and Tumble Mustard (Sisymbrium altissimum)

NOTE Spectacularly colored caterpillar of a high desert butterfly
CONSERVATION STATUS Not evaluated, but widespread in western United States;
more scattered in Canada

ADULT WINGSPAN
1⅜–1⁹∕₁₆ in (35–40 mm)
CATERPILLAR LENGTH
1³∕₁₆ in (30 mm)
PONTIA SISYMBRYII
SPRING WHITE 137

(BOISDUVAL, 1852)

The eggs of the Spring White are laid singly on the flowers
of host plants and hatch within two to three days. First instars
do not eat their eggshells but will cannibalize any nearby eggs.

They feed ravenously, consuming mostly leaves but also flowers
and seedpods; a single individual is capable of defoliating
a plant. The caterpillars feed and rest positioned parallel to
stems, seedpods, or leaf veins and do not construct nests.

They are well camouflaged in early instars but develop bright
aposematic colors in later instars, suggesting that they are
distasteful to predators.

Spring White caterpillars grow rapidly through five instars
and reach pupation about 20 days after hatching. There is
only one spring generation a year, and the pupa oversummers
and overwinters. Pupal diapause for up to four years has been
reported. The caterpillars are vulnerable to viral and bacterial
disease and infections.

The Spring White caterpillar is strikingly colored,
with each segment banded in bright yellow,
porcelain white, and black. The body is covered
in ne setae, and the black head is speckled with
Actual size white dots. The true legs are black, and the
prolegs are white.