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Psyche 9:231-238, 1900.

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PSYCHE.
SKETCH OF THE HABITS OF NORTH AMERICAN ANTS.*- I. BY AUGUSTS FOREL, CHIGNY PR& MORGES, SWITZERLAND. Translated by A. P. Morse.
FAISONS, N. C., July 28, 1899.
To the Belgian Entomological Society,
l3russcls.f
Dear Colleagues :
I am approaching the end of a myr-
mccological excursion in North America,
and find myself here in the hot, low
and marshy, almost sub-tropical region
of North Carolina (between Goldsboro
and Wilmington), under the hospitable
roof of my good friend, Dr. Faisons, to
whose family the village owes its name.
I think that a report of the most inter- esting of the results I have secured will be welcome to you at your next meet-
ing.
I have visited at Toronto, Canada;
Worcester, Mass. (at the home of my
friend and fellow-countryman, Prof. Ad.
Meyer), Morganton (with my genial
colleague, Dr. Murphy, director of the
Insane Asylum), Black Mountain, and
Faisons,-the three latter localities in
North Carolina.
And first, a remark of general charac-
ter relative to what has surprised me in *Extract from die "Rivista di Scienze Biologiclie," vol. ii, no 3, Como, 1900.
t The first part bf this article, as far as the appendix; is taken from the " Annales de la Soci&& entomologique de Belgique," vol. 43, 1899.
the highest degree.
In North America,
with some rare exceptions, the ants do
not construct mounds, either of masonry
or of other materials.
In Europe, as you know, ant-hills
abound in every meadow, in the woods,
in clearings, among the mountains. On
coming to a country where the fauna is
so similar to that of our own, where so
many species only differ from ours in
characters often but little distinctive, where the tillage, the fields, the woods, closely resemble those of Kurope, I was
entirely taken aback when I observed
that the varieties of our most common
species : Lmus saw, dieu~s, fiavm,
formica fuscn, sanguifiea, etc., do not
build any masonry mound, but live in
hidden, subterranean nests, opening
only under stones or on Lhe ground-level by a little crater. But the fact is the
same from Canada to North Carolina.
I was forced to submit to the evidence.
However, the Americans know what an'
" ant-hill " is. When conversing with
them, they refer to it as a great rarity which can be found in such and szich a
forest twenty or thiity miles away. And
on going time you find a colony of
Formica ex.rtr/oidcs, the only species in eastern North America which regularly




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232 PSYCHE. [~ugust, IQOI
makes large, elevated conical mounds of
earth in the forests. I visited two of
these colonies in the vicinity 01 Worccs- ter and of Black Mountain. 'The nests
open by holes situated at the base and
about the periphery.
The workers do
not make excavated roads like our ?*?'/a of Europe.
Besides these, Formica fusca, r. sub-
sericea and faZZiifcf1~2va rarely make
small mounds. As for subsericcq so
common everywhere, I have seen its
mounds only at Niagara, at the side of
the fall.
After mature reflection I have come
to the conclusion that this singular fact does not seriously weaken my theory of
the domes, but rather confirms it. In
my " Fourmis de la Suisse," I have
shown that the elevated dome is used by
our ants to collect and concentrate on
their larvae the radiant solar heat which they so much need, and I cited a num-
ber of facts in support of this view. But thc climate of North America is entirely different from ours. Extremely cold in
winter, it is burning in summer; there
are extremes of which we in Europc
have no idea. The ants consequently
have quite enough heat and sunlight
for their larvae. The dome is superflu-
ous. What they do need is protection
from extreme temperatures. For this
purpose it is necessary either to mine
deeply or to locate themselves in the
shade and in the decaying trunks of
forest trees. And that is what they do.
At least it is in this way that I explain most readily this fact, so surprising by its generality.
Another fact to which Blochmann first
called attention in Europe in connection with Campmotus li@zipeydus is the follow- ing: The nests of ants abound above all
on hill-slopes facing the east. I have con- firmed this statement since then many a
time, and here in America again. In
this case also the explanation seems
simple : The morning sun awakens the
ants and urges them to work. After
noon it is warm enough, they no longer
need the sunshine. Hence the advan-
tage of an easterly exposure which pro-
vicles for a large amount of daily activity. Toward the west, on the contrary, they
would lose the firsthours of themorning, would be unable to work on account of
the heat after noon in summer, and
could do next to nothing in the evening
to make up for it, once the night was
come. Moreover, the night equalizes
very quickly the eastern and western
exposures, so that the latter do not even prolong the afternoon's activity among
those species which work at night.
Ants, then have every advantage in
securing sunshine in the morning and
shade in the afternoon -in America as
in Europc.
Let us pass on to some particular
cases.
The species of Formica of Europe have
American. representatives. To f. rufa,
patensis, truncicola and exsecta of Europe correspond intepq obscu~fer, obscuriven- Iris and exsectoides of America. We
have seen that exsatoides is the only ant 01 eastern America which makes large
domes. It lives in colonies of five to
twenty nests. McCook has seen 1500




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~ugust, qoi] PSYCHE, 233
to 1600 nests of it.
The nests which I
have seen were all quite conical and
built almost exclusively of earth, with
scarcely any commingling of leaves and
fibrous debris. Some have a little more
woody material. Integra, still larger,
more dimorphic, of a handsome red "with
the abdomen ashy black, lives at the
foot of trees or decayed trunks, fills the interstices of bark, etc., with woody de- bris and pine needles which stop up
everything, without forming a dome ris-
ing above ground. The entire nest is
excavated in the earth or in wood. This
species rises upon its hind legs, curves the abdomen, likefratensis (this is not
done by exsectoides) and ejects, as far
as I have been able to observe, some
venom while in this position. Dr.
Faisons has shown me in a pine wood
here at Faisons a considerable colony
of about thirty nests of this species.
These nests were connected with each
other by tortuous roads quite similar to those of our f. prafznsis of Europe, but narrower, deeper, and above all almost
entirely covered, that is to say, carefully covered over with woody materials siin-
ilar to those of the nest. Only at cer-
tain places were they uncovered for a
length of a few centimeters. The fact
is very curious and quite new; I think
that they try thus to protect themselves from birds and other enemies. These
roads lead to the trees and nests. The
latter somewhat resemble those of tmci-
cola of Europe. Obscuripes occurs enly
in the Far West; I have not yet found
obscwiventris.
As Emery has shown, our slave-mak-
ing Formica, F. sanguinea, is represented in America by several varieties. All
those that I have observed at Niagara,
Worcester, Morganton, Tyson's and
likewise here, attack Formica sulisencea, often much larger than themselves, and
carry off the pupae. All tlie formicaries which I have observed have a large
number of slaves, more than in Europe;
the slaves in tlie nest are often more
numerous than the sanguinea. I have
seen several expeditions and two remov-
als of sanguinea. The expeditions take
place in the morning and the pupae are
carried back in the afternoon. All this
takes place as in Europe. I have seen
sonic varieties having the epistoma but
little emarginate make as many slaves
as others having it deeply emarginate.
At Mr. Tyson's (near Black Mountain,
at the foot of Mt. Mitchell) when a large formicary of small sa?zgui?;es changed its nest, the sanguinea almost entirely alone transferred the si.h-ricea,
The latter, although more numerous,
were nearly all in the nest, and allowed themselves to be transported quietly.
In the other removal which 1 witnessed,
the case was the same. This is very
striking, in America, 011 account of the large number of slaves, which are as
numerous or even more numerous than
their despoilers. I11 the High Park at
Toronto I discovered, on the other hand, a large colony of .F. sa?zgu/nea com-
posed of numerous nests (more than a
dozen), built against trunks of dead
trees or by Hie roadside, and having not



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PSYCHE.
a single slave.
These ants, of a deep
red color, slightly emarginate, form their nests of rather woody materials, a little like trtincicola. Their aspect was other- wise exactly like that of other sanguined of Europe and America. They attacked
and pillaged a bagful of suhriceu and
paZZidefulv& which I placed near their
nest, exactly as do other sunguinea,
wild with desire like them, to carry off the pupae. The fact that these insects
lived in a populous colony of many nests and had no slaves remains very curious,
to say the least.
Formica subsericea, which corresponds
to our fusca and is only a race of it,
lives in the earth and in decayed logs.
Only about Niagara have I seen any of
its earthy domes, similar to those of its European congener.
Formica pallidcfuZr~a and its inn~~mer-
able varieties excavate their nests in
meadows and under stones.
Camponotus pe~znsyZvunicn-s and $ictus
are very common in trees, the second in
the north, the first everywhere. Fern-
sylvanicus runs rapidly on the roads and along the trunks, like our pztbescens in the Valais. Pictus is timid and lives in small colonies in the trunks. Maqinatus
and its varieties live as with us in the bark of living trees, and casfane'us is
found in the ground, in the southern
States.
Lasius alieims and az&r live as with
us but with neither domes nor chambers
for their aphides. They mine solely and
arc more retiring, only making here and
there little craters of sand. One finds
them especially under stones. Lasius
myops makes no dome at all. It is
found under stones. In trunks in the
woods is found a large Lasius of a dark
,
and dirty yellow, related to affinis and making its nest in the worm-eaten wood
of the trunks. The Acantfwmyops make
their nests deeply excavated in the
fields. One discovers them only at
swarming-time. In this way I secured
at Morganton a species of it which
is probably new.
PrenoZepis i@arIs marches in regular
files in going to its aphides. Its nest, excavated in the earth, is well hidden
and so deep that I have been unable to
reach the bottom of it.
PrewSepis parvzda makes little nests
everywhere, in wood, in dry leaves or in the earth, and runs about on the turf
and in the forests.
Brachymywzex heeri lives under
- -
stones, sometimes in the woods; it is
widely distributed.
Dorymyrmex pyramicvs is represented
in the southern part of North America
by two distinct races, flavus and niger. Both give off a very pronounced odor
of Tapinoma (anal glands) and nest
exactly like the pyramicns of tropical
America, hunting in the same fashion.
Here at Faisons I found a +cry curious
mixed formicary of these two races.
There were two or three nests of them
several meters apart. The yellow work-
ers and the black workers entered and
passed out peaceably side by side,
working together, and presenting every
sign of friendship. The two forms were




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~ugust, 19or1 PSYCHE. 235
perfectly distinct -no transition form.
I destroyed one of their nests to the
bottom and was so fortunate as to find
there males and females of niger and
the male ofjms, the latter larger and
paler. There is scarcely any doubt pos-
sible as to the following : This must be one of those rare cases of abnormal,
mixed, natural formicaries which I de-
scribed in my " Fourmis de la Suisse."
But this case is certainly not of pre-
datory origin, nor due to the carrying
off of pupae as is the case with Formica. It was without doubt due to the for-
tuitous association of two'fertile females, one of each of the two species, a state of affairs which I have already admitted
possible for certain formicaries of
tnincicolo-pratensis and which is prob-
able also in the association of Ta$inoma- Bothrimnyrmex which I have clescribcd
(I. c.).
The American species of Tafinoma
live exactly like those of Europe and
possess the same odor.
At Morganton I found a little Iri-
domyrmex related to humiZis, which runs
with astonishing rapidity, following in
file, hides its nest in the turf (like Mc- Cooki) or under a stone, and climbs
trees to seek its food. It has a very
strong odor of Tafinoma.
The American Pmera coarctata is very
common in decayed trunks and under
stones. I have made an observation
upon it which is very difficult to make
in Europe ; but here it is quite constant. When one uncovers a nest of Ponera in
a rotten tree one sees their yellow co-
coons gathered in a corner, quite
abandoned by the workers, which do
not try to save them or collect them.
On the contrary they take the greatest
care of the larvae, which they carry off and hide. I suspect that among these
ants, less social than others, the pupae escape unaided from their cocoons, with- out the assistance of the workers.
I found two Amlllyopona in a rotten
trunk and a Proceratiu-m under the bark. Two days ago, in cutting with a chisel
into a rotten trunk in a pine wood, what was my surprise to find here at Faisons
some Erito~. Two blows more showed
me that I had had the good luck to fall
upon a nest with its thousands of larvae and pupae.
To my great surprise all the pupae
were naked, without cocoons, contrary
to those which have been described and
sent to me by W. MUller with Ecilon
ht-rchdli. This little Ecitm, of a reddish yellow, is related to caZ?fornicim and
without doubt described by Emery. I
at once set to work to demolish the nest in order to discover the female, which is yet unknown (with the exception of
Psez~dodichfhadia incerta Andre, of which the worker is unknown).
The trunk was literally impregnated
with Ecitm for a-foot above and a foot
below the soil. Not a square centimeter
of rotten wood was exempt. I demolish-
ed everything, downto the ground under
the roots, without finding the female.
Finally, in looking over the debris, I
found it, a long, broad, blind and wing- less creature with immensely distended




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236 PSYCHE. [~ugust, 1901
abdomen, moving slowly in the midst
of the workers. Its thorax is narrow
and somewhat rectangular. The pedicel
has only one joint, very similar to
that of Labidii-s! The characters are
thus intermediate between the male and
the workcrs. A leap for joy at this dis- covery.
About fourteen millimeters Iong at a guess. Mandibles sublinear, with parallcl edges, without tccth, pointed at the end, slightly curved. Maxillary palpi two-jointed. La- brum emarginate. Scape short, strongly
thickened in the second half. Segments of the funiculns longer tliiin wide. Head
rotundo-quadrate, with a "wide longitudinal furrow from cpistuma to occiput. Thorax
narrow and elongate, especially tlic prono- turn and inesonotum. Pro-mesonotal suture obsolete. Mesonotum oval, subdepressed.
N-o scutellum or intermediate segment,
Meso-metanotal suture distinct, concave in front. Metanotum wider than long, depress- ed, with a wide median impression on the basal face and two strongly rounded protub- erances on each side. Basal face longer
than the declivent face. Pedicel compressed from each side, wider than Iong, wider before than behind, with a superior face and two lateral borders. Its posterior edge is widely and deeply ernarginatc, forming thus on
eucli side a broad obtuse tooth directed back- ward (form of Laliidus). A broad, obtuse tooth beneath, in front.
The abdomen alone, both distended and
elongate (tlie entire female is strongly elon- gate) is about nine mm. long. The pygidinm and liypopygium torm two wide, elongate
disks, the first convex, the second rather flat and passing the first.
Eyes absent. Legs rather long, periniUing locomotion. Tibiae and femora scarcely
sub-depressed. The whole insect shining-, finely punctate, except the thorax and the pedicel which arc plentifully and more
coarsely punctuated. Pile erect, fine, yellow- ish, abundant, pointed, generally distributed. Reddish. Legs and antennae a dirty yellow. I placed a part of the nest in a bag in
order to observe these interesting ants, and I have not yet finished studying
them. Unfortunately there were in the
nest only pupae and larvae of workers.
I found a myrmecophile in it. The
tollowing observations seem to me im-
portant to record : The Ecitons carry
their larvae and pupae, which are very
elongate, by placing themselves astride
over them with their six legs, like
Polyergus but in a more accentuated
fashion. Even the little workers carry
the large pupae in this way, touching
the ground only with the ends of the
tarsi. But by so doing they travel very
fast and have the antennae free. In
the second place, their instinctive faculty of concerted action and of forming in
line quite excels everything I have seen among other ants. Throw a handful
of Ecitons with their larvae down upon
strange ground. Under similar circum-
stances, where other ants scatter them-
selves about in confusion and require
an hour or more (sometimes less) to
arrive at any kind of order, to gather
thcir pupae and especially to examine