leukocyte 203insect, Pyrrhocoris apterus,a native European bug. Grow-
ing in Williams’s laboratory, the bugs went through an extra
stage to form giant, sexually immature, sixth-instar nymphs.
These ultimately died without becoming sexually mature. All
aspects of their rearing were studiously examined, and the
culprit was determined to be the paper toweling used to line
the cages. The toweling was derived from the balsam fir, a
pulp tree indigenous to North America. This was the first
indication of the existence of juvenile hormones naturally
occurring in plants. Molting hormone, alpha ecdysone, has
been found in ferns and various other plants. Apparently
alpha ecdysone may not be at high enough concentrations
to disrupt insect metabolism in every plant where it occurs;
this has been demonstrated in ferns. Perhaps it represents
an intermediate condition in the continual struggle for sur-
vival between plant and herbivore.
Secondary plant substances can also serve as cues
for the insect to feed. Sinigrin, a mustard oil glycoside, is
found in the turnip aphid’s natural foodplants. When sinigrin
issprayed on plants not acceptable to the aphids, feeding
commences and the aphid often does as well or better than
on its normal host. A parasitoid of the cabbage aphid
locates its prey by the smell of sinigrin. Highly aromatic
camphor compounds, safrole (oil of sassafras) and syringin
(a glycoside), are all secondary plant substances charac-
teristic of sassafras. Syringin, a glycoside common in lilac
(genus Syringa), should not be confused with the previously
mentioned sinigrin. R. D. Gibbs in his Chemotaxonomly of
Flowering Plants,published in 1974, states: “Syringin is rela-
tively rare in the Plant Kingdom, and positive results from
the Syringin Test are therefore of considerable interest.”
The geographic distribution of the Saturniidae, as
well as that of other members of the superfamily, com-
bined with high endemism and disjunct distributions, are
all indicative of an ancient lineage. Saturniidae and
Apatelodidae, being ancient lineages, coevolved with the
Lauraceae (among the most primitive flowering plants)
and secondarily adapted to modern plants. Apatelodes
torrefactais still on sassafras, but its largely sympatric
relative, Olceclostera angelica,is on ash and lilac, a pecu-
liar association repeated by other sassafras lepidopter-
ans, notably the promethea moth and the tiger swallowtail.
The latter two also use cherry as does A. torrefacta.Ash,
lilac, and cherry possess syringin, a glycoside that has
been found in virtually all Oleaceae (includes lilac and
ash), cherry, most Lauraceae (including spicebush and
sassafras), as well as Magnoliaceae (magnolia). Privet
also has syringin and is widely used by moth breeders as
a substitute plant for rearing exotic saturniids.
Few lepidopterans feed on sassafras. Significantly,
those that do are among our largest species (giant silk
moths) or are large members of their respective families
(e.g., Epimecis hortaria in the Geometridae). By some
mechanism, possibly secondary plant substances, sas-
safras may be driving lepidoptera toward “bigness.” Swal-
lowtails reared on sassafras produced heavier pupae than
those reared on other, even preferred, host plants. Despite
their long association, smaller members of the Saturniidae,
e.g., Anisota,donot utilize sassafras. W. T. M. Forbes in
The Lepidoptera of New York and Neighboring States
(1923) cites only four records for all microlepidopteran
families on sassafras. This is in contrast to the list for
the Saturniidae: Automeris io, Callosamia promethea,
C. angulifera, Hyalophora cecropia, Antheraea polyphe-
mus, Eacles imperialis,and Citheronia regalis.
Strikingly few lepidopterans have secondarily adapted
to sassafras. The Noctuidae, a diverse family (over 3,000
species in the United States) of recent lineage, has only one
host record for sassafras, Hypsoropha hormos.This species
may have made the jump from persimmon (Ebenaceae),
upon which it and its congeners normally feed, to sassafras
by seeking kaempferol, a phenolic acid held in common by
both plant families. Persimmon is a favorite of the luna moth.
The luna, as a large member of the Saturniidae, is unusual in
not using sassafras. Another secondary specialist is the
spicebush swallowtail that feeds on both spicebush and
sassafras, which have syringin in common. Syringin is rare
in plants and makes it difficult to fathom the pathway that led
the spicebush swallowtail to sassafras. Perhaps safrole is
the common link in this case. Sassafras and pipevine both
possess safrole. Pipevine (Aristolochia) serves as a host for
the pipevine swallowtail, while sassafras serves as a host
for the spicebush swallowtail. The pipevine and the spice-
bush swallowtails even mimic one another.
For a tree, sassafras does very well on poor soils. It
possesses a very deep taproot. One should seek saplings
less than a foot tall for transplant or else plan to do a lot of
digging. It is a favorite deer browse and quickly becomes
eliminated in the understory where deer are dominant. The
variously lobed leaves are unusual and nearly unique for
the Northeast. Sassafras leaves on the forest floor will
attract adult lepidopterans that probe the decomposing tis-
sues. Such feeding behavior has also been observed with
fallen cherry leaves.—Timothy L. McCabe, Ph.D.,is curator of
entomology, New York State Museum in
Albany, New York.