1st moult to 2nd—23 days.
2nd ” to 3rd—14 ”
3rd ” to 4th—14 ”
4th ” to chrys.—28 ”
Chrys. to imago—14 ”
Of Illinois _Nephele_ the stages were:
1st moult passed 8th March.
2nd ” ” 21st ” 1st to 2nd—13 days.
3rd ” ” 9th April. 2nd to 3rd—19 ”
4th ” ” 26th ” 3rd to 4th—17 ”
In chrysalis 17th May. 4th to chry.—21 ”
Imago issued 30th ” chry. to im.—13 ”
The eggs of all these forms are alike, not to be distinguished from each
other. They are conoidal, truncated at top and slightly arched; marked
by about 18 vertical ridges running from base to top, the spaces between
excavated roundly, and crossed by fine striæ; the top is covered with
shallow cells, the outer ones irregularly hexagonal, the inner long and
narrow about a central oval cell.
Nor can the larvæ of these forms be distinguished from each other up to
second moult. The young, of first stage, are very peculiar and quite
unlike what they become after first moult, as well as unlike all other
Satyrid larvæ which I have bred. Under the microscope they look like the
vertebræ of a fish, by reason of the many rows of long hooked bristles,
those of upper and lower rows being curved back, the middle row forward.
General color carnation, with a medio-dorsal line, and three lines on
each side, all of crimson. After 1st moult the color is green, and the
stripes, which are the same in number and position as the lines of first
stage, are dark green; the hairs short and straight.
After 2nd moult the color becomes yellow-green and the stripes are
changed. There is now a dark green one on middle of dorsum and a yellow
one covering the ridge over the feet. On 24th March, I compared Hoboken
_Alope_, Hunter and Illinois _Nephele_, of same age, all lately past
second moult, and could see no difference whatever between them. Some
_Alope_ and Hunter _Nephele_ were much covered with long hairs which were
bent to the surface and gave them quite a shaggy appearance. But others
did not show this peculiarity.
On 18th April, I compared Coalburgh _Alope_ and _Nephele_ from both
localities, all past 3rd moult; length from .68 to .75 inch. All were
yellow-green and in general alike; all had the yellow basal ridge, but
in addition to this, the Illinois _Nephele_ had a distinct longitudinal
yellow stripe on upper part of side, and on either edge of the green
dorsal stripe was a fine yellow line. The Hunter _Nephele_ showed very
faint traces of the yellow side stripe; the _Alope_ none at all.
Comparing another Coalburgh _Alope_ and Hunter _Nephele_ a few days
later, both past 3rd moult, neither showed traces of these lines and I
could see no difference between the two.
At 4th moult all the Illinois _Nephele_, now .7 inch long, showed
same peculiarities as at last stage. No other larva of the several
lots presented the yellow lines so plainly at the same age, that is,
just after the moult; but there were one or more _Alope_ and Hunter
_Nephele_ which gave indications of the side line, and this came out more
distinctly as the stage progressed. But most were without the side line.
Comparing mature larvæ:
One Albany _Alope_, length 1.25 inch, greatest breadth .16
inch; color very yellow-green, no yellow side or dorsal
stripes or lines.
One Coalburgh _Alope_, length 1.6, gr. br. .2 inch; color
yellow-green, the side more green than dorsum; a yellow
side line, quite indistinct.
Hunter _Nephele_, 3 examples; length of one 1.2 inch, gr.
br. .15 inch; of another 1.15, br. .16 inch. Two were
yellow-green, of same shade as nearly all the Coalburgh
larvæ. One was more decidedly yellow, with less green;
but in none was there a yellow side stripe or the fine
dorsal lines.
Illinois _Nephele_, length 1.36, gr. br. .14 inch. Color bright
yellow-green, the dorsum more yellow than side; on the side
as broad a yellow stripe as the one along basal ridge, and
the green dorsal stripe edged by yellow.
Summary as to larvæ:
The five lots could not be separated before 2nd moult. After that,
through the stages to maturity, the _Alope_ from different localities
and the Hunter _Nephele_ varied somewhat in the shade of green, being
more or less yellow; in some yellow prevailing on dorsum, green on sides;
all had the yellow band on basal ridge, either pale or deep colored.
If the yellow side line was present, as in some examples it was, it
was indistinct, or obsolescent. They varied also in the hairy surface,
some having the hairs short and upright, others long and bent down. The
Hunter _Nephele_ could not be distinguished from _Alope_ by any permanent
character.
The Illinois larvæ were deep yellow-green after second moult, and the
side stripe was always present and distinct. The hairs were never long
and bent. The larvæ were distinguishable from all the others.
Comparing chrysalids:
One Albany _Alope_, A; length .56 inch, greatest breadth .21 inch; color
deep green, covered with smooth specks and patches of a lighter color,
but which scarcely affect the general green hue; top of head case, ridge
of mesonotum and ventral edges of wing cases cream color. This was the
only one I obtained, and it produced a male butterfly.
One Hoboken _Alope_, same size and color, and produced a male.
One Hunter _Nephele_, length .6, br. .2 inch; was precisely like the
Albany _Alope_ in appearance, and produced a male.
Another Hoboken _Alope_; color yellow-green, and on the dorsum were three
longitudinal yellow bands, one on middle of abdomen, ending at base of
mesonotum, the others sub-dorsal, extending from last segment to head.
This died before imago.
One Coalburgh _Alope_; length .8, br. .24 inch; bright yellow-green,
covered with the lighter specks and patches, but not so as to obscure
the ground; the wing cases clouded with darker green in long stripes;
the three yellow dorsal bands as in the _Alope_ last mentioned; edges
of head, wing cases and mesonotum cream color. This produced a female
butterfly, with broad yellow band and like the parent.
Another Coalburgh _Alope_, length .6, br. .22 inch; like the foregoing,
being both banded and clouded. Produced a female butterfly, with broad
yellow band.
One Hunter _Nephele_, B; color yellow-green, bands and clouding of wings
present but indistinct. Produced a female.
Three Hunter _Nephele_; all yellow-green, with no bands or clouding; the
edgings cream color. These all gave males. The chrysalis described CAN.
ENT., ix., 143, produced a female, but showed no band or clouds; the
edgings cream color.
Two Illinois examples; length .6, br. .22 inch; color a pale blue-green,
the powdery covering giving a whitish hue to the whole; no bands or
clouds; the edges of mesonotum, head and wing cases white. Both these
gave males. I obtained no females from this lot.
Summary as to chrysalids:
The largest _Alope_ and Hunter _Nephele_ were alike in color and in
dorsal stripes, clouds on wings, and edgings of head case, etc.; but
the bands and clouds were most distinct in _Alope_. All these large
chrysalids produced female butterflies. The plainer and smaller
chrysalids were male. But one female _Nephele_ chrysalis is recorded as
without clouds or bands.
The Illinois chrysalids were of same shape as the rest, but were small
and plain colored, and were blue or whitish-green; the edgings white
instead of cream color. They were readily to be distinguished from any
other.
Results in butterflies:
The chrysalis A, Albany _Alope_, gave a male not differing from many
males taken at Hunter, and which there I always regarded as true
_Nephele_, though off type, being without band, but with a narrow yellow
nimbus about the ocelli and connecting them, the edges everywhere fading
into the black ground.
On the other hand, the chrysalis B, Hunter _Nephele_, gave a typical
female _Alope_, with a broad and clear yellow band. The female which
emerged in 1877 from the Hunter _Nephele_ before spoken of had both
ocelli surrounded and connected by yellow, and stood midway between the
types of the two forms.
The two chrysalids from Illinois, as I have said, gave males; one wholly
dark, the irides without rings; the other had a faint russet nimbus about
them, and over the intervening space was a tint of russet.
The Coalburgh chrysalids produced typical _Alope_, with broad yellow
bands, and like the females which laid the eggs. Therefore outside the
belt of dimorphism _Alope_ produced _Alope_, but inside the belt _Alope_
produced _Nephele_ and _Nephele_ produced _Alope_.
In conclusion:
In Canada the typical _Nephele_ is the only form representing the genus
Satyrus, except that possibly in some localities _Alope_ or intergrades
may appear; but if so, it is only occasionally. In New York and part
of New England a belt of latitude is passed where in one section or
other both these forms fly, besides an endless variety of intergrades.
Finally, _Alope_ emerges in the south from this belt as the only form,
and inhabits a broad zone, which ends about with the southern line of
North Carolina and of Tennessee, but at the southwest flies in parts of
Texas, and has become slightly modified when compared with the _Alope_
of the middle States. And to the west, somewhere between New York and
Illinois, _Alope_ disappears, and a slightly changed form of _Nephele_
presents itself, and occupies the country to and on the eastern slopes of
the Rocky Mountains. In some cases this cannot be distinguished from the
typical _Nephele_, but as a whole, it has taken a departure, and has come
to have differences in its larva and chrysalis. I call this form variety
_Olympus_ (after the companion of the satyr Marsyas when the latter had
his little difficulty with Apollo).
The relationship between _Alope_ and _Nephele_ is in good degree
paralleled by L. _Arthemis_ and _Proserpina_, the first of which occupies
the northern half of the Continent, but is dimorphic with the other in a
belt of latitude which passes through the northern States from Maine to
Wisconsin. _Proserpina_ emerges from this belt on the south, and grades
imperceptibly into _Ursula_, which last changes gradually till it has
acquired a type, in Arizona, as different from that in which it manifests
itself in Pennsylvania as the Texan _Alope_ is from _Alope_ of New York.
This belt is nearly coterminous on both north and south with the belt of
dimorphism in the Satyrids. It is worthy of note also that the dimorphism
of P. _Turnus_ begins inside this belt.
In this last-named species it has been supposed that the melanic form
(confined to the female, _Glaucus_) first originated by accident, and was
afterwards perpetuated and obtained an advantage over the yellow form,
and finally in good degree supplanted it throughout its southern area,
and that the existence of enemies had much to do with the suppression
of one form, while their absence favored the other. What influence
has gradually transmuted _Alope_ into _Nephele_ it is difficult to
conjecture. It could not here be the presence or absence of enemies which
has affected one or other form. And if it is climatic, what can there be
in common between the climate of Canada and Illinois which encourages
_Nephele_ and extinguishes _Alope_?
In a second paper I shall speak of _Pegala_ and the Pacific species of
this genus.
[1] I shall be greatly obliged to any readers of this who will give me
information as to the occurrence of _Nephele_ or _Alope_ west of New
York. Two plates of Part IX Butterflies of North America will be devoted
to the illustration of these forms and varieties, and intergrades, and I
desire to make the history of the species as complete as possible in the
text.