Page 14 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

WHAT IS A CATERPILLAR?

different from the true legs, being fleshy and barrel-shaped, and bearing

hooks or crochets at the base. Most caterpillars have four pairs of prolegs
on the third to sixth abdominal segments and another pair on combined
segments nine and ten. Geometridae caterpil-
lars, however, have only two pairs of prolegs,

one on the sixth abdominal segment and the
other on the tenth, producing a characteristic
walking pattern that has given them the
nickname of “inchworms” or “loopers.”
Limacodidae larvae, the so-called “slug”

caterpillars, have suckers instead of prolegs
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and secrete a liquefied silk lubricant to help
them glide along.

Setae, spines, and shields
Caterpillars are clothed with hairlike struc-
tures called setae, which serve to protect, act
as sensors, or secrete substances; for instance,

the setae of some species of Pieridae butterfly
caterpillars in their early stages produce

droplets of fluid, which appear to help deter

TOP The Crowned predators and parasitoids. Further types of ornamentation include fleshy
Slug (Isa textula), seen

from above, is, like filaments, hardened cones, branching spines, and thoracic shields, all with
other Limacodidae
caterpillars, named primarily defensive functions.
for its sluglike gait.
Its form is also
characteristically fl at,
and it has stinging DISTINCTIVE LARVAE
spines and hairs.
Other insects have a similar larval stage, but caterpillars can usually be
ABOVE The underside
of the Crowned distinguished from other larvae by their characteristic Y-shaped head
Slug reveals vertical
“muscles” that marking, more diverse patterning (grubs are frequently quite dull), and
undulate to create
motion, either forward by their abdominal prolegs, as most other larvae have stocky true legs but
or backward, helping

the caterpillar move no abdominal legs, or no legs at all. The larvae of sawflies (insects of the
along using its suckers,
lubricated by the order Hymenoptera, which also includes bees and wasps) are very
liquid silk it secretes
from salivary glands. caterpillar-like but have a single lateral eye (not six) and have six to eight
(rather than five or fewer) pairs of prolegs.

RANGE AND DIVERSITY
Caterpillars occupy a vast range of habitats, from seed pods to kitchen
pantries, and from hot deserts to mountains and even into the Arctic Circle.