motor neuron 229plants in places judged to be relatively free of predators
and parasites.
That’s the easy part. Nursing the caterpillars to the
cocoon-spinning stage is the hard part. A saturniid cater-
pillar is a nutrient-rich morsel, full of easily digested calo-
ries, an energy bar for a bird, a mouse, or a wasp; or a
milkshake for a stink bug, which inserts its proboscis
through the caterpillar’s skin, secretes a digestive enzyme,
and sucks out the resultant soup. For a parasitic wasp or
fly, a caterpillar is a living pantry within which its grubs,
after hatching from eggs inserted by the female into its vic-
tim, feed on the abundant food storage cells, avoiding the
internal organs and muscles until the final stage of their
lives, when they reduce the hapless caterpillar to a limp
bag or dry husk before their own transformation to winged
adults. These same natural enemies that reduce a fertile
female’s 200–400 eggs to two surviving adult moths (on
average) are capable of launching assaults on captive
caterpillars as well. Containers may protect caterpillars
from predators, but not from diseases, accidents, and
adverse conditions. Screen-topped containers allow air to
circulate, but this causes leaves placed in the containers
to dry out, so the caterpillars don’t get enough water.
Closed containers have sufficient air for several days at
least, but this lack of ventilation produces condensation,
creating a breeding ground for fungal and bacterial dis-
eases. Open-weave cloth bags (“sleeves” in moth breeder
parlance), placed over tree limbs and tied tight around the
branch at the open end, guarantee fresh food and fresh air
but are subject to attack by birds and wasps, which can
peck or chew holes in the sleeves and consume the help-
less caterpillars in short order.
Beginners can expect to raise at least several
species of silk moth everywhere except in an extremely
cold, polar climate. Caterpillars of many species feed on a
much wider range of plants than those they feed upon in
their native habitats; even some exotic species can be
reared on plant genera common almost everywhere, such
as oak, apple, willow, and privet. Eggs and cocoons are
available in season, for a price, from dealers and amateur
breeders. Start with a web search for “moths + livestock”
or“lepidoptera + livestock.” First, however, you should
learn which species will do well on plants available in
your area and in your local climate. Before your livestock
arrives, be ready with all the rearing gear you will need to
care for your captives.
With some time and effort, trial and error, and poking
around, one should eventually be able to find native silk
moths in wild or weedy areas near home. To the sharp-
eyed, a winter walk may yield cocoons hanging from tree
twigs, spun among the shoots at the bases of maple and
poplar trees, or hidden in tangles of shrubbery. In summer
and fall, one can locate caterpillars by looking for missing
leaves (nibbled down to the stem) on trees and shrubs, or
checking bare ground or pavement under tree branches for
caterpillar droppings (“frass”). Once one has female moths,
either from discovered cocoons or caterpillars or from pur-
chased stock, one can attract local wild males by tethering
the females overnight. It is advisable to purchase a stan-
dard work on moth culture before embarking on such an
adventure.
Apatchwork of open and forested land is probably
the best place to look for caterpillars and cocoons, the
more varied the better. Wetlands will have different
species than mature forests, farm hedgerows, weedy lots,
or wind-swept ridges. Silk moths are known to tolerate a
fairly high degree of disturbance and tend to prefer “edge
habitats.” Roadsides, railroad rights-of-way, utility corri-
dors, and even unkempt, weedy corners of industrial yards
are tried and true places for collecting wild silk moths in
all developmental stages. Even cities have scattered,
unmanicured corners where moths eke out a living. The
ailanthus silk moth is one saturniid species that country-
dwelling silk moth enthusiasts must visit a city to find. In
the same urban setting reside several of the native silk
moths, particularly cecropia, polyphemus, and promethea.
During the early 20th century, many authors reported
these species as abundant in eastern and midwestern
cities, the caterpillars and cocoons regularly discovered
by schoolchildren and curious nature lovers on shade
plantings. Toward the end of the century, especially in the
1990s, observers of silk moths reported significant
declines and apparent disappearances of common
species from urban and suburban areas in many areas of
the eastern states. The causes for these declines are
uncertain, but the following factors have been suggested:
increased lighting at night (which may interfere with
reproductive behavior), the release of nonnative parasites
to control gypsy moth and other pests, and general
increased use and accumulation of insecticides and other
toxic chemicals.
Though certain species of silk moths may be common
in settled areas, few ever become sufficiently populous to
be considered pests. Exceptions include the range caterpil-
lar (Hemileuca olivae) in the Plains states, where the cater-
pillars, arrayed with stinging spines, occasionally are so
numerous as to seriously injure the mouths and tongues of
grazing cattle. The cecropia moth has been reported as an(continues)