Page 220 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Nymphalidae
DISTRIBUTION Southern Canada, United States, Bermuda, Mexico,
the Canary Islands, Australia, and New Zealand
HABITAT Almost any open habitat, especially riparian areas
HOST PLANTS Milkweed (Asclepias spp.)

NOTE Colorful caterpillar of arguably the world’s best-known butter y
CONSERVATION STATUS Not evaluated, but numbers in steep decline in North America

ADULT WINGSPAN
3½–4 in (90–100 mm)
CATERPILLAR LENGTH
2⅛ in (55 mm )
DANAUS PLEXIPPUS
MONARCH
218
(LINNAEUS, 1758)

The Monarch caterpillar hatches from cream-colored eggs laid
singly on the underside of young milkweed leaves. Feeding
only on milkweeds, Monarch caterpillars, like other related
milkweed-feeding species, advertise their distastefulness by
their striking, banded coloration. The unpalatability of adults
and larvae to birds and other predators is due to stored cardiac
glycosides, or heart toxins, that are obtained from their host
plant. The caterpillar develops rapidly through five instars,
then forms a bright green, gold-spotted pupa, suspended
from a silken pad. The complete life cycle from egg to adult
takes only around 30 days.

Eastern North American Monarchs migrate up to 3,000 miles
(4,800 km) from Canada to high-elevation forests in Mexico
for overwintering. The species belongs to a family of about 300

milkweed butter ies that generally remain within tropical and
subtropical regions. Numbers have declined in the past 20 years
as a result of habitat destruction and a depletion of milkweeds.

The Monarch caterpillar is smooth and
transversely banded white, yellow, and black,
with the area occupied by the black bands
greater under cool conditions. There are two
pairs of eshy laments at the front and rear,
which the caterpillar waves around when
disturbed. The head is striped black and yellow.
Actual size