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Psyche 9:315-320, 1900.

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Psyche, Vol. 9.
I -
Plate 3.




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Fig. I. Achorutes 7in'icola Fitch, x 25. " 2. Eyes of left side, x 114.
' 3. Postantennal organ of left side, x 504. 4. Antenna, x 78.
5-
Left hind foot, x 294.
" 6.
Left aspect of left mucro and end of dens, x 422. ' 7.
Left aspect of left mucro and end of dens, x 354. 8.
Concave aspect of left mucro, x 504.
" 9.
Extremity of abdomen, x 64.
'; TO.
' Anal spine, lateral aspect, x 434.
" II.
Clothing, dorsum of first abdominal segment, x 114.
I , Arboriitespac/;(~rdi, sp. 11. Eyes of left side, x 294. " 13. Postantennal organ of left side, x 504. 14. right side, x 504.
' 15.
Left hind foot, x 354.
' 16.
' Dens and inucro, x 294.
' 17.
Anal spine, x 366.
'' 18.
Clothing, dorsum of first abdominal segment, x 294.
19.
var. deiztat^ts, var. n. Left hind foot, x 422. ' I 20.
Left aspect of right mucro, x 366.
21. ' Right aspect of left mucro, x 504. ' I 22. ' Anal spine, lateral aspect, x 422. ' 23. ' Clothing, dorsum of first abdominal seg- ment, x I 14,
" 24. Clothing, dorsum of third abdominal seg- merit, x I 14.
2 5.
Achorutes hcrrv~yi sp. 11. Kyes of left side, x 78. " 26. Postantenna1 organ of right side, x 504. ' 27.
8' " 't
' X 504.
28. Antenna, x 78.
c å 29. ' Right front foot, x 294.
" 30.
Left aspect of right dens and inucro, x 147. ' 31.
' Right dens and mucro, x 294.
" 32.
Extremity of abdomen, x 64.
' 33-
it Left anal spine, x 294.
' 34-
Clothing, dorsum of first abdominal segment, x 114.




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PSYCHE.
THE IDENTITY OF THE SNOW-FLEA (ACHORUTES NIVICOLA FITCH).
BY JUSTUS WATSON FOLSOM, CHAMPAIGN, ILL
Under the term "snow-flea," several
species of Achorutes have been badly
mixed. The original description of A.
nivicola Fitch is apparently broad enough to entitle three distinct species to the name of "snow-flea," and to make it
rather difficult to determine which species Fitch meant. Considerable attention to
the subject, however, has enabled me to
identify his species to my own satisfac- tion, and, I hope, to that of other stu- dents, because the synonymy of the
snow-flea concerns not only our Ameri-
can forms, but also involves certain
European species.
The original description of nivicola is
becoming inaccessible, but is reprinted
in full below, from my copy of Fitch's
"Winter Insects of Eastern New York "
(1847)~ and the entire paper has been
rcpublished in Lintner's Second Report.
Podura nivicola. "TILE SKOW-FLEA."
Black or blue-black; legs and tail dull
brown.
Length 0,08.
Body black, covered with a glaucous blue- black powder but slightly adherent, and
sparingly clothed -svith minute hairs ; form cylindrical, somewli~it broader towards the tail. Antennae short and thick, longer than the head.
Legs above blackish, beneath dull
brown and milch paler than the body.
Tail
of the same color '3-ith the venter, shortish, glabrons un its inner or anterior surface, with minute hairs on the opposite side; its fork brownish.
Though found in the sane situations as
the European P. nivalis, ours is a mnch darker colored species. Say's P. bicolor is a larger insect than the one under consideration, and diftersalso in size and in the color of the tail or spring. From the habits of the present species, we should infer that it might be abundant in all the snow clad regions of the northern parts of this continent; it may therefore prove to he identical with tlic P. humicola of Otho Fabricius (Fauna Green- mdictt), of which we are unable to refer to any hut short and unsatisfactory descriptions, which do not coincide well with our insect. This is an abundant species in our forest, in the winter and fore part of spring. At any time in the winter, "whenever a few days of mild weather occur, the surface of the snow, often, over whole acres of woodland, may be fonnd sprinkled more or less thickly with these minute.fleas, looking, at first sight, as though gunpowder had been there scat- tered. Hollows and holes in the snow, out of which the insects are unable to throw themselves readily, are often black wilh the multitudes which here become imprisoned. The fine meal-like powder with which their bodies are coated, enables them to float buoy ntly upon the surface of water, without be-



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coming wet. When tlic snow is melting so as to produce small rivniets coursing along the tracks of the l~~mberman's sleigh, these snow-fleas are often observed, floating pas- sively in its current, in such ninnhers as to form continuou strings; whilst the eddies and sritl pools gather them in such m~riads as to wholl~ hide the element beneath them. Fitch's types of Collembola are not
known to exist, so Dr. Felt wrote me.
Fitch's manuscript notes on the order,
which belong to the Boston Society of
Natural History, I have read and copied, thanks to Mr. Samuel Henshaw ; they
correct the original description thus:
'The antennae and legs are the same
color as the body, not reddish or deep
brown." (Fitch appears to have had
Poclura aquatica in mind, in the first
instance.) He adds, "In the early
spring the buckets ancl troughs of the
manufacturer of maple sugar are often
thronged with these insects."
Although the description of Podura
nivicola is less specific than is desirable, and has consequently been the source
of some confusion,-Kevertheless, ihe
evidcncc which I have collected leaves
no reasonable doubt in my mind, as to
the idcn~ity of Fitch's species.
Three species (here called nh'icoh,
'zai"i:q< and packardi) have been and
may be confused, on acco~~ut of their
superficial agreeincnt in form and color, -and only three have any claim to the
name of nivicola. These three are not
only sharply separated by struclural cle- tails, but are also so different in time of appea~mnce, abundance, h;ibitat, ancl
habits that they can be determined in
the field. The form that I have re-
described as nivicola is the only one
that agrees with the original description in being abundant at any time during
the winter,- and it may be depended
upon to occur in immense numbers every
year, in the manner described by Fitch.
Harveyi seldom appeal's before the first of ~asch, in Massachusetts, where it
occurs on the trunks of pine and other
trees in hut moderate numbers. I have
it as a "snow-flea" from Maryland, but
have never been able to find it as such
in Massachusetts, Mainc, or New York.
Specimens collected for me in a sugar
camp in Maine, for the purpose of this
discussion, proved to be what I had
called nivicola. finally, Mr. MacGilli-
vray, in response to my request, sent me ''snow-fleas " from Osceola, Perm., and
Otto, N. Y., saying, "The one from Otto, N. Y., is the common Ncw York species."
Both lots consisted of the species that 1 had already regarded as the real nivicola. Packard's redescription of nivicola,
whicli subsequent writers have substi-
tuted for Filch's diagnosis, cannot apply to the nivicola established above, on ac- count of the disagreement as to m~icrones and anal spines; moreover, nivicola has
disappeared from Salem and vicinity by
May 7, at the latest,-while Packard
gives May 28 and June 6 as two of his
three dates. It does not apply to
harveyi, for that does not occur much
after April 12, except in the egg. Only
one species remains to which it might,
ancl does, apply. Packard's specimens
of nivicola are lost, unfortunately, but



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March, i~oal PSYCHE. 317
among some unpublished figures (which
he kindly gaveme), of his Essex County
species, are camera-lucida drawings of
every essential detail (claws, mucrones, anal spines, etc.) of his nivicola, a form with which I am familiar, and one that
cannot be the nivicola of Fitch, on ac-
count of appearing too late, if for no
other reason. The species which Pack-
ard called nivicola, is new and is here
named fackardi.
Lintner repeated Filch's account of
nivicola, supplementing it with Packard's description, upon the assumption that
the two descriptions referred to the same species, and added several
notices by
others upon the occurrence 01 " snow-
fleas." Later, Dr. Lintner ('96, pp. 251 to 252) found that doubt attended the
name of nivicola, and, still assuming
that Eackard's redescription was valid,
figured a form from Ghent, N. Y., which
agreed with it; this form is actually that which Packard described as nivicola as
I have learned from some of the original Ghent specimens, which were sent me
by Dr. Felt. The Schoturus nivicola of
Lintner's Eleventh Report, then, is
Achorutes packardi n. sp.
The same report (pp. 253 to 254)
contains the description of Achorutes
diversiceps Lintn.
The types of diver-
siceps, that were loaned to me by Dr.
Felt, confirm my conclusion, drawn from
Lintner's description and figures, that
diversiceps is the form that Etch named
nivicola.
Harvey ('93, pp. 183, 184), without
al-d's redescription, gavc two full form figures to supplement Packard's account. I now have the specimens from which
those figures were made, and find them
to be Packard's species, indeed, and,
therefore, not the nivicola of Fitch.
The queried references in the synon-
ymy below are to popular notices upon
insects that are probably, but not un-
questionably, the snow-flea described by Fitch.
A. nivicola Fitch occurs in Europe
under the names socialis Uzel and spini- fer SchSf. Three Swedish examples of
socialis which were determined by SchiXt and sent me by Schiiffer, agree ac-
curately with our nivicola, Schfitt ('94, p. 82), in fact, adds to his detailed ac- count of socialis, " Es ist nicht unwahr- scheinlich dass die von Packard besch-
riebene Achorntes nivicola, die er meiner Ansicht nach aus guten Grunden mit
Fitch's Podu~a ni~icola gleichstellt, keine andere als obige Art sei." This surmise, incorrect as to the supposed equivalence of Packard's and Fitch's species, is cor- rect as regards the identity of socialis Uzel and nivicola Fitch.
I sent American specimens to Dr.
SchUer, who replied, "Achorutes nivi-
cola Fitch crweist sic11 in den Formmerk- malen mit mcinem Achorutes spinifer
~il~ereinstin~nicnd. Ach. spinifer ist dar- nach eine (kleinere) Farbenvarietiit
von A. nivicola Fitch."
A. nivicola is closely allied to A.
harvey' n. sp., from which it may be
separated by its stout superior claws,
cpestioning the applicability of Pack-
ovate inferiors, small anal spines on a




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31 8 PSYCHE. [~firch, 1902
cylindrical segment, and clothing of long subequal setae.
Each of the three species discussed
above is characterized below. Unless
otherwise specified, the material referred to was collected by the author, and is
owned by him ; examples of each species, however, have been given to the Muse-
um of Comparative Zoology, Cambridge,
Mass.
Achorittes nivicolu Fitch,
(Figs. 1-1 I.)
Podurn nivicola Fitch, Amer. JOUI-n.
Sc. Agric., vol. i; (1847) pp. 283-284 and vol. 6 (1847) p. 152; Winter Ins. E. N.
Y. (1847) pp. 10-11 (reprinted by Lint-
ner, Second Kept. (1885), pp. 204, 205,
244. Fitch, Rural New Yorker, vol.
8 (1857). ? McMinn, Proc. Acad. Nat.
Sc. Phila., vol. 4 (1849) p. 246. ? Ash- ton, Proc. Ent. Soc. Phila., vol. I ( 1861) p. 32 (repr. Lint. Sec. Rept., p. 204).
? Walsh, Riley, Amer. Ent.,vol. I (1869) p. 188. ? Field and Forest, vol. 2
(1877) pp. 146-147 (rcpr. Lint. Sec.
Rept., p. 205).
Achorutes socialis Uzel, Thys. Boh.
(1890) pp. 69-70, tab. 2, figs. 16-19.
Scl~ott. Syst. Vcrb. (1894) pp. 81-82,
taf. 7, figs. 6-8. Schriffer, Coll. Ham- burg (1896) p. 172.
Achorittes a'inidu MacGillivray, Can.
Ent., vol. 23 (1891) p. 274.
Schoturus niuicola MacGillivray, Can.
Ent., vol. 25 (1873) 13. 316. Dalla
Torre, Gatt. Arlen Apt., (1895) p. 13.
Achorutes spinzbr Sch5l'fer, Coll.Ham-
burg (1896) pp. 172, 174, taf. 3, fig. 51. Achomtesdiversiceps Lintner ! Eleventh
Kept. (1896) pp. 253-254. figs. 23-25.
(Rct. to Country Gentleman, Mar. 22,
1879, 11' 327.)
Dark indigo blue throughout (fig. I).
Eyes
(fig. 2) sixteen. Postantennal organs (fig. 3) of four elements. Antennae (fig. 4) almost as longas the head, with segments as 7: 9: 10: is; basal seg-iricnt subglobose, second ;ind third suI~cyli~~drical,fo~~rth rounded conical. Body elongate, abdomen snl~fusiform, last segment cylindrica!. Superior claws (fig. 5) stout, slightly curved, unidentate two fifths from the apex ; inferior claws half as long, basally subovaie, apically acicuhir ; one long tenent hair with a minute knob; distal tibia1 hairs minutely knobbed. Manubrium as long as the rest of the l'urc~ila; dcntes (figs. 6, 7) stout, subcylindrical, apically broad and rounded, bearing four to six prominent., acutely conical teeth, of which one is more lateral than the others ; in addition, there are usually fil'teen to seventeen small outer teeth ; mucrones (fig. 8) inserted on inner side of the apex of each dens and rather boat-shaped; in profile, suboblong, feebly curved, apex refuse or emarginate. Anal spines (figs. 9, lo) two, small, conical, erect, upon low, separated papillae. Clothing (fig-. 11) of numerous long curving hairs and few short curved
setfie. Length, 2 mm.
Norway, Maine, May 7, F. Howe, Jr.;
Orono, Maine, March, April 15, May 6,
F. L. Harvey. Arlington, Massachu-
setts, April 12, Belmont, Massachusetts, April 19, May 5 ; Winchester, Massachu-
setts, February 9, R. W. Hall; Karner,
New York, April 26, J. A. Lintncr (N.
Y. State Coll.) ; Otto, New York, J. H.
Comstoclc ; Osceola, Pennsylvania, A.
D. MacGillivray.




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March, qoz] PSYCHE. 319
(Figs. 12-18,)
Achorzttes nivicola ' Packard, Thys.
Essex Co. (1873) pp. 29-30. Lintner
Second Rept. (1885) p. 203. MacGill-
ivray, Can. Ent., vol. 23 (1891) p. 274. Harvey I Enl. Ncws, vol. 4 (1893) p.
183, figs. 5, 6.
Schotz~rzis nivirola Lintner ! Eleventh
Rept. (1896) pp. 251-252, figs. 21, 22.
Dark indigo blue througllout.
Ejes (fig.
12) sixteen.
Post-antenna1 organs (figs. 13,
14) of four elliptical-oval elements.
Anten-
nae shorter than the head, with segments as 5 : 8 : 7: 10 ; basal
segment globose, second
and third slightly expanding, fourth suhcy- lindrical with rounded apex. Body subcy- lindrical. Superior claws (fig. 15) broad, almost straight, untoothed; inferior claws of hind feet two fifths us long us the superiors, slender, lanceolate, acuminate; of theremab ing feet, one i'o~~rlh as long, small ; tenent hair stout, exceeding the large claw, apex bent. Manubrium as long as the rest of the fnrcul~i; denies (fig. 16) one sixth as long, oblong, distally rounded, terminating in an uptm-ncd tooth. Anal spines (fig. 17) two. three fifths as long as a superior claw, stout, fecbl, curved, erect; upon contiguous papil- lae. Clotliing (fig. 18) of many stout-cm-ving serrate settle of moderate length and fewer long erect capitate setae, more or less serrate. Length, 2 mm.
This is the species that Packard redes-
cribed as nivicola Fitch. Packard's
specimens are not in the Museum of
Comparative Zoology, with the rest of
his Essex County material, but I am in
possession of his original drawings,
which leave no doubt as to what species
he regarded as nivicola. Harvey and
Lintner depended upon Packard's
account of nivicola, and the specimens to which they applied that name are, indeed, the same species that Packard had in
hand: this I have learned from an
examination of the identical specimens
that Harvey and Lintner used in prepar-
ing the papers mentioned above in the
synonymy.
As I have good reasons (already
given) for believing that the nivicola of Packard is not that of Fitch, and needs
a new name, I gladly name it packa~di,
Toronto, Ontario, June 26, R. J.
Crew; Orono, Maine, February, F. L.
Harvey; Cambridge, Massachusetts,
April 17 ; Lexington, Massachusetts,
May 10, 11 ; Ghent, New York, April
13, E. C. Powell (N. Y. State Coll.) ;
Ncwark, Maryland, January 24, Beck-
with (N. Y. State Coll.).
This species is frequently found on
red maple trees, crawling on the trunk
or remaining under the bark or in crevi- ces, especially about the base of a tree. I have occasionally found it under the
bark of pine, oak, and apple trees, or
about the roots ; or clustered under moss on a stone. Full grown individuals
occur from mid April until the middle of June ; a second brood begins to appear
late in June and has disappeared by
the last of August. I have twice (April
22, 29) found abundant eggs of this
species under the loose moist bark of
red maple roots, protected by the sod;
they were pale yellow, spherical, 135
micra in diameter, occurred in irregular masses and hatched in a little under one month