Page 60 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Papilionidae
DISTRIBUTION India, Southeast Asia (southern China, Chinese Taipei,
and Indonesia)
HABITAT Open forest
HOST PLANTS Members of Rutaceae, including Toddalia asiatica,
Euodia meliifolia, Zanthoxylum rhetsa, and Citrus spp.
NOTE Caterpillar with menacing eyespots, exhibiting classic mimicry
of swallowtail larvae
CONSERVATION STATUS Not evaluated, but common within its range

ADULT WINGSPAN
4–4⅞ in (100–125 mm)
CATERPILLAR LENGTH
2 in (50 mm)
PAPILIO NEPHELUS
YELLOW HELEN
58
BOISDUVAL, 1836

Early instar caterpillars are bird-dropping mimics with earthy
colors and a glossy, even slimy finish. The fifth and final instar

caterpillar is a complete departure in appearance—eyespots
and a widened thorax successfully emulate a menacing “snake’s
head” appearance, while the caterpillar’s real head is tucked
safely beneath. All stages possess an eversible, malodorous
osmeterium to startle and repel potential threats. The chrysalis
is angular and green and can be mistaken easily for foliage.

The Yellow Helen (or Black and White Helen, according to

subspecies) belongs to a clade of related swallowtail butterflies,
the helenus group, or Helens, which are typically large,
predominantly black butterflies with long tails and a large, white

area on the hindwings. Like other Papilio species, P. nephelus has

evolved specific kinds of protective adaptation, such as crypsis
(larval and pupal coloration), chemical (osmeterium secretions
that change with age and size), and mimicry (bird-dropping and
eyespot markings and posture). These progressively protect the
species against different types and sizes of predator, from ants to

birds, throughout its life cycle.

The Yellow Helen caterpillar is mottled green.
On the prominent thoracic shield, eyespots with
pupils are connected by a green band, and a
similar band with lighter, sinuous markings
Actual size traverses the thoracic boundary. There are two
sets of marbled, oblique bars on each side of
the abdomen, but only the cranial pair meets
dorsally in a distinct V-shape. The caudal set
taper toward the dorsum but do not connect.