Page 270 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Nymphalidae
TRIBUTION
DISTRIBUTION Southwestern United States into Mexico
DISTRIBUTION
DIS
HABITAT
A
HABITAT T Lower mountain hills
HABIT
HOST PLANTS S Beardtongue (Penstemon spp.)
T PLANT
HOST PLANTS
HOS
NOTE Caterpillar that is protected by the toxic chemicals it ingests
NOTE
TE
NO
CONSERV A TION S T A TUS Not evaluated, but generally common if occasionally rare at the
CONSERVATION STATUS
CONSERVATION STATUS
periphery of its range
ADULT WINGSPAN
1¼–1¾ in (32–45 mm)
CATERPILLAR LENGTH
1⅜ in (35 mm)
POLADRYAS ARACHNE
ARACHNE CHECKERSPOT
268
(W. H. EDWARDS, 1869)

Young Arachne Checkerspot caterpillars are gregarious,
hatching from clusters of about 40 eggs laid on the underside
of young green beardtongue leaves, which the caterpillars eat.
The larvae hibernate half grown and become solitary feeders
in spring, but may reenter diapause if the host plant or weather
conditions are unsuitable. Caterpillars and adults are poisonous
Actual size
to birds and mice because of iridoid glycoside chemicals they
ingest from Penstemon leaves. The pupa is white with black
marks and orange bumps.

There are several generations of adults during the summer, and
the bright orangish adults can be seen on hilltops, where males
wait for females to arrive for mating. Several hundred other
species of Checkerspots occur in the northern hemisphere and
American tropics. Young caterpillars of all species are gregarious
on various herbs or bushes, and all but the youngest caterpillars
are adorned with numerous spines that help protect them from
mice and birds.

The Arachne Checkerspot caterpillar is boldly
striped in black and white, and is covered with
branching, orange-and-black spines. The top
row of spines is black. The head is orange and
pubescent, the true legs are black, and the
prolegs are orange.