Page 29 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

CATERPILLAR DEFENSES

the caterpillar shoots out the gland, which resembles a snake tongue and

glistens with an odiferous secretion that repels predators. Many caterpillars
from other butterfly and moth families possess a similar eversible fleshy
“neck” gland, located ventrally beneath the head on the anterior margin
of the first segment. These organs (called adenosma) also contain chemicals

that appear to repel ants and other predators.

SAFETY IN NUMBERS
Aggregation, or gregariousness—group feeding and resting—is
a behavioral tactic to reduce the odds of any single individual being

attacked; this is often practiced in
early instars before other defense 27
methods develop. Communal
larvae may also build silken webs,

supports, and platforms to help
keep the community together.
In some caterpillars, including
the California Tortoiseshell (Nym-
phalis californica), the less impor-
tant rear end strongly resembles the

crucial head end in a bid to confuse
predators. Early instars of this
species feed and rest communally, and the striking appearance of twice above Gregarious
behavior by final
the number of “heads” in a community may well reduce the risk of real instar caterpillars
of the Banded
heads being attacked by a predator. Swallowtail (Papilio
demolion) may
enhance camouflage
on a host plant
ANT BODYGUARDS leaf, but if this
fails, simultaneous
Some caterpillars, particularly those of the Lycaenidae butterfly family, eversion of odiferous
and snake tongue-like
have developed a defense strategy based on recruiting ant bodyguards to osmeteria may deter
predator attacks.
repel threats from parasitoids and other predators. Although ants are a
significant natural enemy of most other butterfly larvae, lycaenid
caterpillars have evolved to produce something that many ant species
love—sugar-rich honeydew—and most of the larvae have a functional

“honeydew” gland, producing sugars and amino acids, which the ants
consume. The physical presence and activity of ants swarming over the
caterpillars and substrate effectively prevent parasitoids and predators
from attacking the caterpillars. A persistent predator, such as a spider or
parasitoid wasp, will eventually be overpowered by ants and discarded.