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Psyche 7:39-46, 1894.

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PSYCHE.
HABITS OF THE ACULEATE HYMENOPTERA.-11.
&
BY WILLIAM H. ASHMEAD, WASHINGTON, D. C. Mr. E. Baynes Reed, in "Notes on
Megachile brevis Say" (Can. ent. v. 3,
1871, p. 210) has figured this species
and records the following respecting it. While inspecting during the past summer, the fruit orchard of a friend residing in this neighborhood, my attention was attracted by the peculiar appearance of the leaves of a young plum tree. At the first glance, I
thought it might be affected by Aphides, but, on closer examination, I found unmistakable evidence of the work of a leaf-cutting bee, in the circular holes in many of the leaves, and on opening one of the coils of leaves, of which there were four or five, I discovered the curious chambers of the bee, each con- taining a half grown grub comfortably
ensconced, with its modicum of food. I
took some of the coils home, but only suc- ceeded in rearing two perfect insects.
The genus Osmia, structurally, is
closely allied to Megachile, but the
species composing it construct nests
entirely different. They have received
the name of "mason-bees," from the
way they construct small earthen cells
under stones, in burrows excavated in
decaying wood, rotten posts and twigs,
in deserted snail-shells, in cynipidous
galls, or elsewhere.
Very little seems to be known respect-
ing the habits of the North American
species, Dr. Packard, in his Guide,
being apparently the only author who
has written anything about them. From
his observations and those published
abroad, the species exhibit great diver- sity of habits and should be more care-
fully studied, as this diversity of habits will no doubt be found correlated with
structural differences that will justify sub-generic divisions of this large genus. The cells are constructed of sand,
earth, or clay, agglutinated and mixed
with pebbles or the raspings of wood,
held together by a glutinous substance
secreted by the female ; internally the
cells are always smooth, but externally
they are rough in conformity with the
material used in their construction.
These cells vary in number in each nest, usually from 10 to 20 being found
together. Each cell contains a deposit
of honey-paste for the subsistance of the larva, only a single larva or egg being
found in each cell. Curtis found the
enormous number of 230 cells of the
European Osmia ĺ´parietin attached to
the under side of a large flat stone. Mr. L. 0. Howard, in his article in the
Standard Natural History, calls atten-
tion to a remarkable case of retarded
development in this species observed by
Mr. Frederick Smith. "From a quan-
tity of cells collected in Scotland in
1849, about one-third only had given
forth the adult bees. Some of the re-
mainder issued the following year, while about thirty-five remained in the larva
state until May, 1851, when they trans-
formed and issued a month later."
One of our largest species, Osmia lig--
nivora Pack., according to Dr. Packard,
Purhr 7 039-46 (prc.1903). hfp //psyche aitclub orgfV7.0039 htd



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40 2'6' ZTHZ?. [March 1894.
industriously tunnels out an elaborate
burrow in maple several inches from
the bark, wherein it forms its cells.
The tunnel was over three inches long and about three-tenths of an inch wide. It con- tracted a little in width between the cells, showing that the bee worked intelligently, and wasted no more of her energies than was absolutely necessary. The burrow contained five cells each half an inch long, being rather short and broad, with the hinder end rounded while the opposite and next to the one ad- joining, is cut off squarely. The cell is some- what jug-shaped, owing to a slight constric- tion just behind the mouth. The material of which the cell is composed is stout, silken, parchment-like, and very smooth within.
The interstices between the cells are filled with rather coarse chippings made by the bee.
The bee cut its way out of the cells in
March, and lived for a month afterwards on a diet of honey and water. It eagerly lapped up the drops of water supplied by its keeper, to whom it soon grew accustomed, and whom it seemed to recognize."
Os&a Zig'naria and 0. pacified Say,
on the contrary, build their cells under stones, while 0. simillima Smith, one
of the smallest of our species, constructs its cells in the deserted oak-galls made by Amphiboli$s confluens Harris, thus
agreeing with Osmia gaZZarunz of
Europe. I have also observed another
species in a deserted oak-gall in Florida. Species in the genus Anthid%
according to Westwood, "frequent vari-
ous woolly-leaved flowers, stripping off the down with their toothed jaws for the purpose of forming their nests "
The Anthidii, as with certain Odyneri,
although said to nidificate usually in
holes in trees, will sometimes choose
odd situations for their nests, the British species Anthidium manicaturn having
been twice observed to nidificate in the key-hole of a garden gate. Prof. West-
wood thus describes one found in a
similar position.
There were twelve or fifteen cells or cases consisting externally of a loose covering of white down within which was another cover- ing more compact and smooth on the inside and within this was contained an oval cell, of a strong coriaceous texture, and of a chestnut color. This latter I consider to be the cocoon formed by the larva itself, because some of my woolly cases contained a mass of matter apparently consisting of dried pollen-paste and the egg deposited with it which had . probably on some account proved abortive ; and in these there was no oval chestnut- colored cocoon. It was in February that this nest was discovered, at which period some of the cells were empty, the inhabitants having forced off a circular cap from the top of the cocoon and escaped; others, however, con- tained full-sized grubs.
No observation seems to have even
been published on any of our numerous
species, although many of the species
are so plentiful.
The genera Coelioxys Latr. and
Stelis Panzer are parasitic bees, both
having been bred in Europe ; the
former from the cells of Megachile,
Anthophora and Anthidium, the latter
from Osmia. No observations on any
of the American species have ever been
recorded.
Although the parasitic habits of
Stelis was so long known it was not
until last year that the true inward his- tory was given in the publication of
Mr. C. Veshoeffs observations on




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March 1894.3
PSYCHE.
Stelis minzda Nyl. (2001. anzeiger,
vol. xv, 1892, pp. 41-43).
This species was found to be para-
sitic in the nests of Osmia leucome-
laena Kirby which constructs its cells
in hollow twigs.
Dr. Riley's summary
of this species is as follows : -
At the bottom of the cell the female Osmia first puts a layer of pollen which is to serve as food for the nearly full grown larva. Above this pollen, the bee commences to
store the cell with prepared bee-bread.
At
this moment the female Stelis watches her opportunity to lay an egg in the Osmia cell, the egg thus being always near the bottom (posterior end) of the food mass. Unaware of the presence of the parasite egg, the Osmia female continues her work, and, after nearly filling the cell, deposits her own egg on the top (anterior end) of the food mass. The cell is then closed with a layer of
macerated particles of plants and a second cell prepared above the first. The Stelis larva hatches but little earlier than that of the Osmia, and both larva feed on the food-
mass, the parasite larva at the bottom, the host larva at the top. The latter remains stationary at the top and grows very slowly; the parasite larva grows more rapidly, and gradually works its way upward through the food-mass, thus gradually approaching the Osmia larva. The crisis finally comes; the Stelis larva encounters the Osmia larva-a short but deadly combat ensues-the Osmia larva is easily overpowered and killed by the much larger and stronger parasite, and its body is devoured by the latter within one or two days.
The genus B-peolus is stated by our
American authorities to be parasitic in
the cells of Colletes, evidently based
upon an observation of an English
authority, Shuckard, who claims to
have bred Epeolus variegatus from
the cells of one of these bees.
This statement must, however, be
erroneous, as it does not agree with
observations of mine made on a com-
mon American species. It was evi-
dently based upon insufficient data,
just as was found to be the case re-
pecting St. Fargeau's statement about
Sphecodes being parasitic in the cells
of Halictus.
The past summer, while in Missis-
sippi, I was fortunate enough to
stumble upon several specimens of
Epeolus donatus Smith making their
burrows, and I am thus enabled to
assert that this species is not parasitic but builds cells and deposits honey-
paste for its offspring, just as
many
other solitary bees. My observations
throw grave doubts upon the reliability
of Shuckard's statement and lead me
to believe that he had cells of both
Epeolus and Colletes mixed together
in his breeding jars, when his speci-
mens were reared.
On the plantation where I was stay-
ing, near Utica, Miss., JSpeoZus dona-
tus was observed making its burrow
in hard clay, beneath a cotton-gin
shed, into which I had run to escape
a passing rain storm which came
on
suddenly, while I was investigating
cotton-insects in a cotton-field near by. My attention was first attracted by
the buzzing of the bees ; for, as they
returned from the field to enter their
burrows, before alighting they invari-
ably made several circles above the
mouth of their burrow, all the time
making a very loud humming or buzz-
ing noise, very noticeable and
which
ceases only as they reach the ground.




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42 PSYCHE. [March 1894.
I thus easily discovered several burrows and afterwards saw females in the act
of digging them.
All except three or four had the
peculiar tubular entrance formed of
cemented clay at their mouth, similar
to those made by Anthophora and other
solitary bees. Burrows that had not
the tubular entrance at their mouth,
evidently had it originally, but it had
become destroyed by persons or cattle
walking over the ground where the
burrows occurred.
The clay was very hard and dry, and
the burrows extended in it obliquely
downward to the depth of two or three
inches and then became horizontal, ter-
minating after reaching a depth of eight or ten inches. At the bottom the female
builds her cell, composed of cemented
clay, 15 mm. long by 10 mm. in diam-
eter at widest part, the cell being
slightly constricted towards the top,
where its diameter is only 8 mm. ;
interiorly it is perfectly smooth and
glistening from some thin secretion that covers its surface, while exteriorly it is rough from the small particles of clay of which it is composed. Some of the
cells dug up were only partially fin-
ished ; others were completely finished, either empty or contained the egg or
the larva.
The egg was always enclosed in a
ball of honey-paste that was perfectly
white and consisted of numerous white
granules mixed with honey. Only one
egg was found in each cell. The egg
is much elongated and slightly thicker
toward one end, perfectly white, with
its surface feebly shagreened. One
taken from its cell August 15, measured
4 mm. long, by 0.8 mm. in diameter, at
its thickest part.
A larva, taken August 16, doubled
up in its cell, measured 12 mm. long,
while the broadest abdominal segment
measured only 5 mm. It tapered very
much toward the head, was of a white
color, with the derma finely, irregu-
larly transversely shagreened, the seg-
ments being well defined ; the head was
small, rounded, measuring transversely
I .5 mm. ; the eyes were not apparent
except by a slight elevation, which was
scarcely separable from the cranium ;
the mandibles were well defined, black
01- piceous at the tips, the tips being
truncate and roundedly einarginate but
not sufficiently emarginate to form
distinct teeth ; the clypeus was trape-
zoidal, the anterior edge with a medial
emargination ; while the other parts of
the mouth were not developed, appear-
ing as three lobes, a lobe beneath each
mandible, with the third placed beneath
and more or less covering the other
two.
Although still incomplete, these ' ob-
servations prove this bee is not parasitic and will serve to stimulate further study on the habits of our species.
It may be well to record here that
while studying this species, I observed
a Mutillid moving cautiously into one
of the burrows, which on capturing
proved to be S$haero$hthaZma simil-
ha Smith. It is probably parasitic
on this bee.
The species belonging to the genera
Nomada Fabr. and Melecta Latr. are
stated to be parasitic on different soli-



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March 1894.1
tary bees, although additional evidence
is needed to establish the sort of para- sitism it is.
Dr. Packard has reared Nomada im-
bricata Smith and N. vincta Say
(= pulchella Sm.) from the nests of
Andrenu vicina Smith; and the
former also from the cells of Halictus
$araZZelus Say and found :
Both full-grown larvae and pupae of differ- ent ages, up to theadult Nomada, ready to take leave ofits host. It seems, therefore, that the newly hatched young of Nomada must feed
on the pollen mass destined for the Andrena. But there seems to be enough for both genera to feed upon, as the young of both host and parasite were found living harmoniously
together, and the host and their parasites are disclosed both at the same time.
Is it not just possible that this socia- bility of the two larvae is fictitious and lasts only just so long as the food
supply is sufficient for both ? When
the food supply gives out, will they not also attack each other just as in the
case of Stelis ?
It. seems to me that here we have an
admirable illustration of the origin of
parasitism. We have (I) commensa-
lism, (2) parasitism, induced by hun-
ger, and (3) genuine parasitism, which
is induced or acquired by the two
former. conditions, until finally it
becomes permanently acquired through
heredity. The same thing is strikingly
exhibited in the family Cynipidae
where we find (I) gall-makers, (2)
commensals or inquilines and (3)
true parasites, again in the family
Chalcididae, in the Eurytomides where
we have (1) gall-makers or plant-
feeders (Isosoma and allies), (2)
commensals or inquilines (Eurytoma
and allied genera) and (3) true para-
sites (Bruchophagus, Eurytow etc.) .
The same state of affairs occurs also in the fig-insects (Blastophaginae) , and
in the gall-inhabiting Toryminae.
Family II. ANDRENIDAE. In hab-
its and structure this family is in all
respects very closely allied to the pre- ceding. About 150 species, distributed
in 14 genera, are already known from
boreal North America.
All of the genera, except the genus
Prosapis Fabr., which like Ceratina,
in the preceding family, excavates the
stems of brambles, etc., burrow gal-
leries in the ground in which they
place their cells. At one time two or
three of the genera, Sphecodes, Augo-
chlora and Prosapis, were considered to
be parasitic or inquilinous in the cells of some of the others, but have since
been shown to be honey-producers like
the rest.
The nests of comparatively few of
our genera have been studied in detail.
Andrenu vicina Smith, as observed
by Mr. J. H. Emerton and others, ex-
cavates a perpendicular gallery in the
ground to the depth of several inches
or more, branching off from which it
then excavates short oblique galleries
in which the cells which are lined
with a muscous-like secretion are
placed.
The nests are built in the latter part
of April and during May. The cells
are then filled with a ball of pollen and



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PSYCHE.
[March 1894.
honey, those nearest the surface being
provisioned first, those at the bottom
last. The period of development from
egg to imago is about five weeks, so
that images issue all through July and
August.
The genera Cilissa Leach, Nomia
Latr. and Halictus Latr. have similar
habits.
The nests of Azg-Zochlora -purely as
recorded by Say (Bost. Journ., v. I,
1837, p. 397) were found in the soft,
decomposing sap-wood of the oak and
hickory, between the bark and the
solid wood.
The cells are oval, horizontal, not sym- metrically disposed though many are paral- lel. These cells are composed of par-
ticles of the decayed wood agglutinated
together. Each cell contains one individual subsisting on a yellow-pollen.
In the same
assemblage are the young of all ages to the perfect insect.
The habits of none of our species of
Prosafis and Colletes have been
observed.
A Dipteron Miltogramma $uactata
has been reared from Colletes in
Europe.
Family III. CRABRONIDAE. This
family is represented in our fauna by
over one hundred species, unequally dis- tributed in seven genera.
The species,
according to the "records," exhibit the
greatest diversity in their habits. West- wood says, '^Those whose economy has
been clearly traced make their cells
in wood, boring into palings, posts,
willows, stumps, etc."
No observations have been made on
our species belonging to the genus
Oxybehs, but in Europe they are found