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Psyche 4:130-131, 1883.

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130 PSYCHE.
[J:inurtry-Febiunry 1884.
the wild strawberry from time imine-
morial.
One would say that here were all the
conditions of a most determined stniggle for existence, in which one or mole of
these species must succumb. It is in-
deed interesting to see how the issue
is evaded, and an adjustment reached by
which competition is reduced to a mini-
mum. The Colas'pis larva makes the
earliest attack upon the plant. beginning its work upon the root certainly as early as the first of May (half-$own incli-
viduals having been taken on the 15th).
and finishing in June, all being of full size and prepaiing to pupate by the end
of that month. Next comes Paria, in
July and August, neither extreme of
its period being exactly defined by our
observations; and finally comes Sce/o,
donta, adults of which were copulating
on I July, j oung larvae occurring 7 ALI- gust. AS far as now known, the Scelo-
donta larva is left in undisturbed pos-
session dming the remainder of the
year ; although there is a break in our
observations for October. Certainly by
November it lias completed its work,
and retired, full-grown, and ready to
transform, into its subterranean cell.
It seems clear, f~irthermore, that this
curious succession of periods is related to a difference of habit with respect to hibernation. Undoubtedly Scelodonta
winters as a larva, and Paria as an
adult. As Colas$is larvae were only
half-grown on 15 May, they veq probix-
bly hatched from the egg that spring;
and as the adult Co7as$is emerged about
two months before the new brood of
Paria, it seems hardly possible that
both could have developed from eggs
laid that spring; but it is, much more
likely that Colasfis hibernates in the
egg. On this hypothesis, we shall have
the eggs of Colas$is deposited in au-
tumn, those of Paria in spring, and
those of Scelodonfa in midsummer, the
first species hibernating in the egg, the second as an adult, and the third as
full-grown larva, v^ it11 the necessary re- sult that their attacks upon their common food plant are delivered successiv el).
The immense advantage deri~ ed from
this arrangement is evident, when we
reflect that by this means as many of
each of the species are fed upon the sur- plus stnictuies and supernumerary in-
dividuals of the strawbeiry (that pla t
being a continuous grower), as it would
be possible to maintain of aJl three if
they came into simultaneous competi-
tion.
COLLECTION AND PRESERVATION OF DIPTERA.
BY SAMUEL WENDELI. W1LLISTON. NEW HAVES, CONN. From dearly purchased experience I
that a few hints will be of service to
have learned the necessity of care in the collectors of diptera and similar ' the collection and preservation of ento- insects. mological specimens. and it may be For collecting I use a cyanide-bottle,



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January-February iSS+ J PSYCHE. 131
which, although objected to by Euro-
pean dipterologists, I have found the best and most convenient. But I do not
mean an ordinary cyanide-bottle, for
specimens collected in such are worth-
less for scientific or other purposes. I select several two ounce [60 c. c.], wide- mouthed bottles of the same form, and
carefully line the bottom and sides with a good quality of blotting-paper. Good,
firm corks are selected, which are inter- changeable in the different bottles : in one of these corks a small hole is made, in which it is better to fit a small metal- lic ferule ; a strip of blotting-paper is then coiled within this cavity, and it is over this that a few drops of a solution of cyanide of potash is poured. It is
useless to coll ect flies in a bare bottle ; the insects soon exhale moisture snf-
ficient to ruin them. The blotting-
paper prevents this, and the cork can
readily be removed from one bottle and
put into another when a sufficient quan- tity of flies is collected. flfoi.~/z~~/e of any kind injures flies. Some flies,
such as the hairy bombyli'idae, should
always be pinned when caught. For
this purpose a small, tight, pith-lined
box may be carried in the pocket,
together with a vial of benzine to kill
the flies.
In the earlier part of the season many
rare specimens of cliptera may be 013-
tained by beating. For this purpose a
I employ rather heavier net-wire, to
which a pointed net of cheese-clot11 is
attached. On such occasions it is neces- sary to carry with one a larger bottle
with a little cotton-wool in the bottom, and a vial of chloroform in the pocket.
By thrusting the end of the net, with its contents, for a few seconds into the
chloroform bottle, one can then remove
the specimens undisturbed. Very mi-
nute flies it is expedient to preserve
alive in small bottles filled with paper clippings and thro~igh the cork of
which a small glass tube is thrust
nearly to the bottom. For a collecting
net, after many experiments and fail-
ures, I have found most serviceable a
siniple, rather light, brass wire, soldered together to form a ring about 28 cm. in
diameter and firmly attached to a light
handle about one metre long. The net
is made of very coarse bobbinet lace,
the most serviceable and, in the end.
cheapest material. The net should be
readily handled with one hand.
For the collection of diptera a few
hints here will suffice. The best sea-
son in New England is June, vet speci-
mens may be collected every month
j11 tlie year. In May and the early part of June, beating will give excellent
results. A little later, patches of black- berry (Rz~bt~s), wild cherry .(PT'ZIEZIS), dogwood ( C'O~VZ~I~'), Canada thistle
( C?'?T/?I,T~I), or other melliferous blos- soins, will afford desirable specimens.
It is better to let specimens come to the collector than to go hastily about look- ing for them. I have spent six hours
about a patch of Co~wz~s $an/czda/a
not ten metres in diameter, and been
amply repaid. But few specimens are
found in shady woods; those few are
to be sought for there. The favorite
place for tabanidae, as indeed for most




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PSYCHE.
[ January-February 1884.
flies, is on the border of woods, open
glades, meadow lands, etc.
Specimens should not be allowed to
remain over night unpinned. The
large specimens may be pinned through
the thorax, preferably with japanned
iron pins. They should be placed on
the pin only low enough so that the
head may be grasped with the thumb
and forefinger without danger to the
specimen. The wings should never
be si>read. Spreading not only renders
the specimens more difficult to study,
but it spoils the natural appearance of
the ii;sects, and is a positive injury to them for the cabinet. All that is
necessary is to push aside the wings so
that they will not conceal the abdomen.
Minute specimens should be pinned
with fine iron wire from the underside,
and then pinned upon small strips of
thin cork, the upper surface of which
has been covered with white paper, and
through the other end of which a pin
is thrust. Small specimens should
never be glued to bits of card-board,
as is commonly done with coleoptera.
Only one specimen should be placed
on the piece of cork.
The greatest enemy to dipterological
collections is dust: insects can be
guarded against, but it is difficult to
exclude dust, unless tight cases are
used. Dampness and mildew do often
much mischief.
A good dipterological specimen must
be unrubbed, unmoistened, not dusty
nor greasy, and with the wings un-
spread. It is quite as easy to collect
good specimens as poor ones and much
more satisfactory.
[For other articles on the collection and preservation
of diptei-a, see Rec., 157, 2335,
33967 3404 and 3405.1
MUSEUM PESTS OF SERVICE TO THE
ENTOMOLOGIST.- Trogoderma t a d e
has heretofore been viewed with un-
mixed hatred by entomologists, but for
the last few days I have been showering
blessings on the heads of a particular
colony which had established itself in a pill-box containing some hundreds of
specimens of a pteroinalid reared from
the cocoons of A$an/eZes aletiae Riley.
It is true that nothing but fragments of the pteroinalid remained after the Tro-
goderma had been at work for a year
or more, but among these fragments
I have found a number which illus-
trate points in the external anatomy
better than the most careful dissections. Certain points concerning the form and
structure of the metanotum-alway s
hard to study in the complete insect, and very difficult to dissect out, owing to a disagreeable tendency to break through
the middle as readily as at a suture-
are admirably exhibited by these acci-
dental anatomical preparations. Truly
it is an ill wind that blows no good.
L. 0. Howard.
Washington, D. C.. 25 Jan. 1884.




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