Page 24 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

right Feeding damage
by early instar
caterpillars of the
Pink-edged Sulphur
(Colias interior) on
Vaccinium (blueberry)
host plants is
distinctive. This type
of feeding, leaving
stems and veins
untouched, is known
as skeletonization.
VORACIOUS EATERS

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A caterpillar is designed primarily to consume. How much it eats and the

quality of its food determine its growth rate and health, as well as adult size
and reproductive success. In a caterpillar’s final instar, the amount of food
consumed increases fourfold, providing the stored water, fat, and protein
to carry it through the pupal stage to adulthood. For species that do not
feed as moths or butterflies, it is the last chance to build the reserves needed
to survive the rest of their short life.

EATING AND DIGESTION
Caterpillars chew leaves, or other food, using serrated mandibles, or jaws,
that move from side to side, while a pair of sensory organs below the

mandibles taste the food and push it back into the mouth, where it mixes
with saliva. From there, it enters the digestive system, basically a long
tube—the caterpillar version of an alimentary canal. The chewed food is
stored in the crop, a pouch-like organ, before entering the largest section
of the tube, the midgut, to be digested and absorbed. Indigestible food

accumulates in the hindgut and rectum, and is expelled through the anus
in small, hard pellets called frass. Most caterpillars do not drink water,
extracting it instead from their food; one notable exception is the Drinker
moth caterpillar (Euthrix potatoria), which imbibes water droplets.

SOURCES AND FEEDING TACTICS
Caterpillars usually feed on plants, consuming all parts or specializing on
leaves, buds, stems, flowers, or seeds. Some develop on a single host plant
species, while others are highly polyphagous, feeding on a wide variety of