Page 28 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

CATERPILLAR DEFENSES

mid-instar Mourning Cloak (Nymphalis antiopa) larvae. Late instar

California Sister caterpillars thrash, and display and move their mandibles
as if to bite. Mature caterpillars of some swallowtail butterfly and hawkmoth
species have eyespots on the thorax, which are enlarged when the larva is
threatened, often giving it the appearance of a small snake. Similarly, the
below When under
threat, mature head capsules of some larvae and the pupal heads of many Hesperiidae
caterpillars of certain
species, like this species have markings or modifications that resemble a vertebrate face,
Common Rippled
Hawkmoth (Eupanacra which again could deter a potential attacker. Other nymphalid caterpillars
mydon), puff up their
anterior segments, have elongated horns at one or both ends of the body, which are waved
conceal their true
legs, and enlarge their around in a threatening manner if a predator approaches.
eyespots, giving them
the appearance of a The spiny armature of many caterpillars turns soft, palatable larvae into
26 small snake.
prickly, tongue-stabbing mouthfuls that only a few predators can tolerate.
bottom Paired
horns, spines, false Spines, in combination with other tactics such as thrashing, mandible-
eyespots, a “nose,”
and black mandibles baring, curling, and dropping, are all likely deterrents, and make it more
combine to create an
intimidating “face” on difficult for parasitic wasps to alight on the caterpillar and insert their eggs.
the head of this fifth
instar California Sister Caterpillars of many species across many families engage in chemical
(Adelpha californica)
butterfly caterpillar. defense, by using toxic chemicals sequestered from host plants or by
producing noxious compounds from
benign chemicals. The best-known example
is probably the Monarch (Danaus plexippus),

whose caterpillars sequester cardenolides or
cardiac glycosides from milkweed host
plants. These plant poisons make Monarch
larvae, pupae, and adults unpalatable to

vertebrate predators. The striking, yellow,
black, and white banding of Monarch larvae
is quickly recognized by birds as indicating
distastefulness; as a result, similarly marked
caterpillars may also be avoided.

First instars of most Pieridae butterflies
carry oily droplets on the tips of their dorsal
setae; these droplets contain chemicals that
repel ants and other predators. Swallowtail

butterfly caterpillars possess a unique
chemical defense in the form of an eversible
forked, fleshy gland, called an osmeterium,
located in a slit behind the head and colored
yellow, orange, or red. When threatened,