Page 19 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

FROM EGGS TO PUPATION

suspended animation, or diapause. In late summer or fall, some caterpillars

prepare for overwintering by seeking refuges, such as curled leaves, seed
pods, under rocks, or other sheltered locations, where they will be buffered
against the elements. Here, a lowered metabolic rate and radical
biochemical changes, including synthesis of a kind of “antifreeze,” protect

them against extreme cold. Species living in hot, dry Mediterranean or
desert climates, where temperatures frequently reach 100–115ºF (38–45ºC)
and plant life is often sparse, face a similar challenge, entering summer
dormancy, or estivation, and delaying pupation and adult emergence until
fall, when conditions are better for survival and reproduction.

Caterpillars may reenter diapause multiple times if environmental
17
stimuli signal the onset of unfavorable conditions. Post-diapause, 17
checkerspot (Euphydryas) butterfly caterpillars recommence feeding in
late winter or early spring on fresh host plant growth, but if a lack of

moisture affects that growth, the larvae become dormant, potentially living
for two to three years with only short periods of development annually.
Caterpillars living at high elevations, such as those of the Arctic Fritillary
BELOW Preparing to
(Boloria chariclea), depend on timely snowmelt to enable them to feed and pupate, the Common
Wood Nymph
complete development in time for the normal midsummer flight period. (Cercyonis pegala)
hangs in an inverted
In late spring, after diapause, these caterpillars appear to measure day J shape. This well-
camouflaged but
length to determine if they can complete development in time. If not, they vulnerable prepupal
stage may last from
overwinter twice, as an early instar then a late instar. Climate, elevation, 12 to 48 hours
and food plant also affect the number of broods developed during a year. depending on
the temperature.

PREPARING TO PUPATE
When nearing maturity and pupation, full-fed
larvae often change color, most “shrink” to a
certain degree, and some enter a wandering phase,
the “wanderers” seeking sites away from the host

plant. Some go underground, some hide, and
others build a protective cocoon or blend in with
the background, either through coloration or by
creating a broken outline. This high degree of

crypsis, and the talent of wandering prepupal
caterpillars for finding secluded pupation sites,
means the particularly vulnerable pupal stage of
butterfly and moth metamorphosis is the least
likely to be seen.