Page 137 - 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 British Columbia to New Mexico
HABITAT Arid lands, shrub-steppe, deserts, canyons, and watercourses
HOST PLANTS Rock cress (Arabis spp.), tansymustard (Descurainia spp.),
and Tumble Mustard (Sisymbrium altissimum)

NOTE Camouflaged caterpillar that develops rapidly
CONSERVATION STATUS Not evaluated, but common within its range

ADULT WINGSPAN
1¾–2 in (45–50 mm)
CATERPILLAR LENGTH
1³∕₁₆ in (30 mm)
PONTIA BECKERII
BECKER’S WHITE 135

(W. H. EDWARDS, 1871)

Becker’s White eggs are laid singly on the flowers and seedpods

of host plants. The caterpillars hatch after three days and
partially eat their eggshell. Their development is rapid, with
pupation occurring just 14 days after egg hatch. The whole
cycle, from egg to emerging butterfly, takes little more than
three weeks. The caterpillars feed on all parts of the host plant,
although young instars prefer flowers. No nests are made, and

survival is based on camouflage. Prepupal caterpillars wander,
and pupation may occur on or off the host plant.

The pupa is attached by a silk girdle, usually to a twig, and
resembles a bird dropping. The number of generations produced
by this species appears to depend on the quality of the host plant.
Caterpillars feeding on good-quality hosts produce a further
generation, while poor-quality hosts result in diapausing pupae.
Males are aggressive and sometimes “fight” to mate with newly

emerged females.
Actual size

The Becker’s White caterpillar is bright
yellowish green with distinct intersegmental
yellow bands. Large, black dots occur on each
segment, each carrying a long, white seta, giving
the caterpillar a hairy appearance. The head is
white and yellow with black spots. The caterpillar
turns pinkish brown prior to pupation.