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Psyche 8:47-49, 1897.

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PSYCHE.
A NEW HYPOTHESIS OF SEASONAL-DIMORPHISM IN LEPIDOPTERA. - I.
BY ALFRED GOLDSBOROUGH
{I). Previous Researches.
Iii 1830 it was discovered that the
two European butterflies Vanessa
prom and Vanessa levam were in
reality only different broods of one and the same species of insect. The chrysa-
lids of the last summer's brood winter
over and give rise to butterflies of the light colored, or levana, type. Then
follow several summer generations all
of the prorsa type, having wings of a
dark brown color. The chrysalids from
the last prorsa generation winter over
and produce levanas the next spring.
There is, however, in addition to the
forms levana and prorsa, an intermediate form, porima, which is very rarely met
with in nature; and, indeed, it was on
account of the extreme rarity of this
intermediate form that the older natura- lists failed to recognize that levttna and prorsa were only different forms of the
same butterfly.
Dorfineister ('64) showed that if
chrysalids which were naturally destined to produce the prorsa form be subjected
to cold, they will give butterflies which are not prorsa but porinxt, and that if
the cold is as intense as oå¡C the butter- MAYER, CAMBRIDGE, MASS.
flies which issue are hardly distin-
guishable from typical levanas. Later
in 1875 Weismann repeated these experi-
ments with the same result. He also
tried the reverse experiment. That is,
he took chrysalids of the last summer's
brood of butterflies and subjected them
to the heat of a green house, varying
from i,$'-3iå¡C The ch~ysalids how-
ever remained over winter and pro-
duced levanas the next spring just as
they normally would had they been
exposed to the winter's cold. Weis-
mann was deceived by this experiment,
and lead into the false conclusion that
it was impossible for heat to cause
chrysalids destined to produce levanas
to give rise to anything but levana. In
1895, however, he published a paper in
which he acknowledges that heat can
cause the chrysalids which are naturally destined to produce levana to give rise
to butterflies of the porima, or even of the prom type. His final conclusi~ns
('95 p. 644) are as follows: levana and
prorsa follow each other in a regular
cycle, levana appears in April, prorsa
in June. By the influence of cold
chrysalids destined to give rise to the
prorsa form can be changed into levana-
Psidie 8 047-50 (pre- 1903). hfp //psyche aitclub orgWS.0047.htd



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48 PSYCHE. [~p~il ,aq7.
r,
1 his change is not accomplished how-
ever without resistance, for the chrysa- lids show a strong tendency to produce
prorsas, as is seen by the production of many porimas among the butterflies
whose chrysalids have been subjected to
the cold. On the other hand the third,
or autumnal, generation of chrysalids
shows a strong tendency to over-winter
and produce butterflies of the levana
type next spring. Heat of ~7~-3o'C.,
can, however, counteract this tendency
and cause some of these chrys a1 I'd s to give rise to porimas, or even to prorsas. In (1875-'82) Weismann was lead
into the conclusion that levana represents the more primitive or ancestral form of
the butterfly which existed in Europe
at the time of the gl.icial epoch. As
the mean temperature at that time was
much lower than at present, and the
summer was short, the butterfly was
probably single brooded, and consisted
of only the form levana. The form
prorsa, however, gradually made its
appearance after tbc glacial epoch when
the climate became milder, and the but-
terfly began to produce summer genera-
tions. The form prorsa, according to
this hypothesis, is phylogenetically
newer than levana, and the application
of cold simply causes it to revert to its ancestral type. The levana form, on the
other hand, could not possibly be made
to revert into prorsa because prorsa is
phylogcnetically younger than levana.
In 1895, however, Weismann finds that
he is mistaken in this for, it will be re- membered, hesucceeded in forcing chrys-
alids which were naturally destined to
produce levana to give rise to prorsa by subjecting them to a high temperature.
He is therefore obliged to modify his
former (187;-'82) conclusions, and
finally decides that there are two kinds of seasonal-dimorphism ; one of which
he calls " direct seasonal-dimorphism,"
and the other " adaptive seasonal-
dimorphism." By ^ direct " seasonal-
dimorphism Weismann means the direct
effect of the temperature stimulus upon
the pupae at the time when the colors
arc produced. This direct influence
may induce chemical changes, etc.,
which determine the coloration of the
wings. An excellent example of direct
seasonal-dimorphism is afforded by
CJzrysopham~.~ phhas where heat
causes the pupae of any brood to give
rise to dark colored butterflies ; while cold induces them to give light golden
red forms.
In <' adaptive " seasonal-dimorphism,
on the other hand, we have the nddi-
tional f'ictor that one or both of the
dimorphic forms possesses a peculiar
advantage correlated with the season in
which it occurs. Under these circum-
stances there has arisen, through the
agency of natural selection, a tendency
to produce different forms in the differ- ent seasons.
For example we find in-
herent in the pupae of Vanessa levana-
ftrorsa, two separate, and- distinct, ten- dencies ; the one to produce levana, and the other prorsa. The tendency to
produce levana is strong in the over-
wintering pupae, while the tendency to
produce prorsa is strong in the summer
pupae. These tendencies can however




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be altered by temperatures which are
the reverse of the normal ones to which
the pupae would be subjected in nature.
Cold is only the initiatory stimulus for the levana tendency, and heat for the
prorsa tendency. An example of adap-
tive seasonal-di~norphistn way be af-
forded by Vanessa levana-@orsa where
the summer form prorsa may gain some
advantage by its general resemblance
to Limenitis sibylla and camilia,'
while it. is possible that the overwin-
tered form, levana, may gain some
advantage from its resernbl+nce to the
dead leaves of the spring woods.
We shall now describe a few more
experiments the bearing of which will
become apparent when we discuss the
results of the researches.
In 1875, '77, 'So, Edwards performed
some interesting temperature experi-
ments upon Papilio e x . There are
four generations of Pafilio +ax in
West Virginia, three being summer
generations, and one which winters
over in the chrysalis state, and may pro- duce two distinct forms of butterflies,
walshii and telamonides. The summer
generations are all alike and belong to
the form marcellus. The eggs laid by
the spring forms usually. change into
pupae from which the summer form,
marcellus, emerges ; some of these
pupae, however, winter over and pro-
duce walshii or tela~nouides the follovi- ing spring.
Edwards subjected the pupae reared
from eggs laid by captive females of
walshii or telamonides, to the cold of an ice house for periods varying from 11
days to 2 months.
These pupae would
normally have produced only marcellus,
but owing to the influence of the cold,
the majority of them gave rise to butter- flies colored like telamonides. A few,
however, defied the cold and remained
marcellus, and still fewer were con-
verted into the coloration of walshii.
Edwards also tried the reverse experi-
ment, that is he subjected the over-win- tering chrysalids to the heat of a green house, but they gave rise to telamonides and walshii just as they normally would
had they been exposed to the winter's
cold,
Rut by far the most remarkable exper-
iments upon the effects of temperature
which have been performed thus far, are
those of Fischer ('gj) upon Vanessa
antio/a. When the pupae of this form
are placed upon ice at 0-1' C. the but-
tcrfly is greatly modified. The ground
color is a darker velvet brown than in
the normal antiopa, and the blue spots
are greatly enlarged, and changed into
an intense violet-blue. Fischer de-
scribes this form in the " Gubener ento- mologischer Zeitschrift as V. antio$a
artemis. A temperature of 35' C.,
however, produces a form which is
exactly the opposite of that produced
by cold. Fischer describes it in the
" Gubener entomologischer Zeitschrift,
July 1894" as V. antio-fia, aberratio
e/ione. The ground color is lighter
than the normal, and the blue spots
much reduced in size. But the most
astonishing result obtained by Fischer
came from experiments with abnormally
liigli temperatures. IIe subjected fresh



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50 PSYCHE. [April I&?.
pupae for about three hours, and then kept on ice at from oo-I' C ; indeed daily for 2-3 hours to a temperature of
among these specimens he obtained a
40'-42" C, keeping them during the typical abernitio artemis. The blue remainder of the time at 3s0-38' C. spots were much enlarged and the The results were very striking and ground color much darkened. similar to those obtained from pupae
NOTES ON NEW ENGLAND ACR1DIDAE.-111. 0EDIPODINAE.-III. BY ALBERT P. MORSE, WELLESLEY, MASS.
11. ARPHIA Stal.
A~$Jzia Stal 1873. Recensio or-
thopterorum, i, 113.
16. Arphia xanthoptera Germ.
Figs. 16, 16a.
Oedijoda xanthoptera. Germar,
in Burmeister's Handbuch der Entomo-
logic, ii, 643, (1838). Scudder, 469 ;
Smith,- Conn., 372.
Tomonotus xanthojferus, Thomas,
105.
Ayphia xantfto/lera. Saussure, 67 ;
Female), 39; Morse, 105; Beuten-
miiller, 297.
This species is perhaps the Locusta
suZphrea of which Harris speaks as
occurring in September.
Antenna:<?, 10-11 ;
9, 9-11.5. H.
fern.: 3, 14.6-17.3; 9, 17-18.5.
Teg.: 8, 22.5-27; Q , 26-5-30,
Body; 8, 21-25 ; 9, 28-32. Total
length : 3, 3-34 ; 9 , 34.5-40 mm.
While most likely to be confused
with its congener if any, this locust
should be readily distinguished even by
the tyro by the characters indicated in
the Key, which are not merely specific
in value but pertain to different series in the genus. While the two species
overlap slightly in season sulphurea
has mostly disappeared at the time
xanfhopfem begins to be common.
This species varies much in color,
some specimens being almost black,
others bright reddish or yellowish
brown. The wings of younger exam-
ples are noticeably paler in color but
the general tint of a large series is quite uniform. Sometimes the veins, and
rarely
the venules of the whole disk,
are somewhat suffused with brownish.
In about one-fifth of the specimens
examined the subfrontal shoot extends
one-half of the distance to the base of
the wing. I have yet to see an orange
winged example from New England,
but in a seiies collected for me at Clay City, Ill., by S. W. Denton, about one-
half of the specimens have the disk of
the wing of a deep reddish orange. It
is possible that this is a distinct race or even species but the structural differ-
ences are extremely slight.
Xanthoptera is equally common with
its congener of the spring-time and is
found in the same situations, viz., amid



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