Page 13 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

WHAT IS A CATERPILLAR?

grub. In most caterpillars, the head

is conspicuous, although in fami-
lies such as Lycaenidae it may be
retracted into the thorax. There are
six simple, lateral eyes (stemmata)

to help the caterpillar distinguish
between dark and light and give it
some spatial awareness. There is a
short antenna on each side of the
mouth, and the mouthparts consist

of a pair of jaws, or mandibles, 11

bounded by an upper flap (labrum)
and lower structure (labium). The
mandibles swing from side to side,

“shearing” through vegetation, and
often bear small, sharp, toothlike projections. Located centrally on the ABOVE The head
of a caterpillar is
lower side of the head is the labial spinneret, the secretory structure through its control center,
containing its key

which modified salivary glands discharge silk that is used by the larvae in sensory features and
the organs it needs to
various ways—sometimes to bind foliage or create a silk web, or during feed. The head above
is that of the spiny
pupation to suspend a chrysalis or construct a cocoon. Atlas Moth caterpillar
(Attacus atlas).

Thorax, abdomen, and legs BELOW All caterpillars,
like this Mulberry
The thorax is small, muscular, and made up of three segments, each bear- Silkworm (Bombyx
mori), have a three-
ing a pair of true, jointed legs. The abdomen, consisting of ten segments, part body—head,
thorax, and abdomen.
is the largest part of a caterpillar and where food is digested and processed. The true legs are
jointed legs, while the
There are pairs of spiracles (respiratory pores) on all of the abdominal fl eshy prolegs, present
in most species,
segments except for the last two. The abdominal legs or prolegs are quite lack musculature.

head thorax abdomen
upper abdomen
setae

spiracles
true (or thoracic) legs
claspers
epicranium (or anal prolegs)
abdominal prolegs