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Psyche 4:3-11, 1883.

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PSYCHE.
THE SCALES OF COLEOPTERA.
BY GEORGE DIMMOCK, CAMBRIDGE, MASS.
Altho the following paper is mainly
a description of a few forms of scales
of coleoptera, on some of which the
scales have not before been noticed, and on others of which they have been more
or less fully described. a brief outline of the history and bibliography of the
knowledge of the ac'ales of insects in
general and of coleoptera in particular
may not be amiss as an introduction to
these descriptions.
According to Mayerl and Schneider*
the scales of lepidoptera were first
mentioned, by Fabricius, in 1600, were
later mentioned by Malpighi, in 1650,
and since then by many other observers.
Up to the beginning of the present
century the literature of this subject is of little importance except historically, and I will cite only the names of
Bonanni, Leder~ntiller, Reaumur, Rose1
and Swainmerdamm, who made men-
tion, to a greater or less extent, of the ' Mayer, F. J. C.
Ueber den Staub der
Schmetterlingsflugel. (Allgem. med. Cen- tral-Zeit., 1860, jahrg. 29, p. 772-774.) Ka- yen, Bibl. entom,
Schneider, R. Die Schuppen an den ver-
schiedenen Fliigel- und Korpertheilen der Lepidopteren.
Dissertatio . . . Halis Saxo-
num, 1878.
Also (Zeitschr. f. ges. Naturw.,
1878.)
scales of lepidoptera in their works.
During the present century the literature of this subject has increased rapidly,
and among the authors of leading
papers which treat mainly or consider-
ably of the scales of lepidoptera are, in chronological order, Deschamps (I 835) ,8 Bowerbank (1838) ,-' Craig ( 1839) ,5
Ratzeburg (1840),~ de la Rue (1852) ,'
Semper (1857) ,' Kettelhoit (1860) ,9
Deschamps, B. Recherches microsco-
piques sur l'organisation des ailes des 16pi- doptferes. (Ann. sci. nat., 1835, s. 2, v. 3, p. 111-137.)
Bowerbank, J. S. On the structure of
the scales on the wings of lepidopterous in- sects. (Entom. mag., 1838, v. 5, p. 300-304.) Craig, E.
On the configuration of the
scale of butterflies' wings, as exhibited in the microscope. (Edinb. philos. mag., 1839, s. 2, V. 15, p. 279-282, fig.)
Ratzeburg, J. T. C. Die Forstinsekten . . . Bd. 2, 1840.
de la Rue, W. On the markings on the
scales of Amathusia horsfieldii. (Trans. rni- cros. soc. Lond., 1852, v. 3, p. 36-40, pi. 2.) Semper, C. Beobachtunguber die Bitdung
der Fliigel, Schuppen und Haare bei den
Lepidopteren. (Zeitschr. f. wiss. Zool., 1857, v. 8, p. 326-339, pi. 13.)
Kettelhoit, T. De squamis lepidoptero-
rum. Dissertatio . . . Bonnae, 1860.
Put-he 4 003-1 1 (pre-1903) hfp //psyche aitclub or@I-t-OOOH html



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Mayer (1860) ,l Landois (1871) ,lo and
Schneider ( 1878) .2 Even special
nlodifications of scales, called by
Sc~~dcler~~ androconia, have been found
on the males of a large number of
butterflies, and have given rise to con- siderable discussion in regard to their
function. Androconia were first discov-
ered about 1825 by Baillif, who termed
them plumulae. They have been
discussed since in papers by numerous
writers, among whom may be men-
tioned Deschamps3, Scl~neider,~ Watson
(I 865- I 869) ,12-15 Wonfor (I 868- I 869) ,I6 Anthony (r8yz) Fritz Muller
(I 877) ,19 Scudder (1877) ,I1 Weismann
lo Landois, H. Beitrage zur Entwicklungs- geschichte der Schmetterlingsflugel in der Raupe und Puppe. (Zeitschr. f. wiss. Zool., 1871, v. 21, p. 305-316, pi. 23.)
l1 Scudder, S. H. Antigeny, or sexual
dimorphism in butterflies. (Proc. Amer.
acad. arts and sciences, 1877, v. 12, p. 150- 158.1
Watson, J. On certain scales of some
diurnal lepidoptera.
(Mem. Lit. and phil.
soc. Manchester, 1865, s. 3, v. 2, p. 63-70.) l3 Watson, J.
On the microscopical exam-
ination of plumules. . . (Entom.
mo. mag.,
1865, V. 2, p. 1-2, fig.)
l4 Watson, J.
On the plumules or battle-
dore scales of lycaenidae.
(Mem. Lit. and
phil. soc. Manchester, 1869, s. 3, v. 3, p. 128- 133, PI- 1-3.)
l5 Watson, J. Further remarks on the
plumules or battledore scales of some of the lepidoptera. (Mem. Lit. and phil. soc. Man- chester, 1869, s. 3, v. 3, p. 259-269, pi.5-7.) Wonfor, F. W. On certain butterfly
scales characteristic of sex. (Quart. joui-n. micros. sci., 1868, n. s., v. 8, p. 80-83, pi. I ; 1869, v. 9, p. 19-22, p. 426-428.)
(1878) 23 and Aurivellius (1880) .21
Weismann believes that it is not iinpos- sible that these scales give out an etherial oil secreted by the cells at their bases. Without discussing the correctness of
Weismann's view, the extensive litera-
ture devoted to the scales of lepidoptera, of which I have given only the outline,
shows how broad the subject is. But
how is it with the scales of insects
other than lepidoptera? Are forms as
interesting as androconia waiting the
search of thoro investigators ?
Leeuwenhoek, in 1680, and Swain-
inerda~nni,~~ in the next century, figure the scales of the wings and body of
CztZex, and Wei~mann,~~ in I 864, speaks of scales on Sarcophaga carnaria.
These are all the references which I
know to diptera having scales and I
l7 Anthony, J. The markings on the battle- dore scales of some of the lepidoptera. (Mo. micros, journ., 1872. v. 7, p. 1-3, pi. J-2.) l8 Anthony, J. Structure of battledore
scales. (Mo. micros. jo~ii-n., 1872, v. 7, p. 250.1
l9 Muller, Fritz.
Ueber Haarpinsel, Filz-
flecke und ahnliche Gebilde auf den Flugeln mannlicher Schmetterlinge. (Jena. Zeitschr. f. Naturw., 1877, bd. 11, p. 99-114.)
20 Weismann, A. Ueber Duftschuppen.
(2001. Anzeiger, 1879, Jahrg. I, p. 98-99.) 21 Aurivellius, C. Ueber sekundare Gesch- lechtscharaktere nordischer Tagfalter. (Bi- hang till k. Svenska vet.-akad. hai~dlin~r, 1880, bd. 5, n :o 25.)
22 Swammerdamm, J. Buch der Natul-. . . . Leipzig, 1752.
23 Weismann, A. Die nachembi-yonale
Entwickelung der Musciden. . . . (Zeitschr. f. wiss. Zool., 1864, bd. 14, p. 187-336.)



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PSYCHE.
Jan.-Feb. 1883.1 5
will add here to their number, that I
have found scales upon the legs of a
species of Roas from Germany.
Scales have been examined, but not
extensively studied, which were ob-
tained from thysanura (Le-pisma, Ma-
chilis and Podura). L. Land~is~~
speaks of scales in Phthirius, but it is evident from his description that they
are not homologically and structurally
like the scales of lepidoptera.
Le~dig,~~
to whose paper I shall have occasion
to refer later, mentions scales resem-
bling those of lepidoptera on spiders
of the genus Salticus. says
the 9hryganidae are '' with hairy or
scaly wings," but I know of no special
studies made upon the scales of these
insects.
As far as I have been able to
discover, scales have only been recorded on hemipterous insects in the case of
the curious dimorphic form of A-phis
aceris (originally described by Thorn-
ton, in I 852. as Phyllofhorus testudi-
dus} which is figured and briefly
described by Pa~kard,~' and have never
been recorded from hymenoptera.
I come now to what is more strictly
the subject of this paper, the scales of 24 Landois, L.
Untersuchungen uber die
auf dem Menschen schmarotzenden Pedicu-
linen. Anatomie des Pktki~ius inguinaIis Leach. (Zeitschr. f. wiss. Zooll, 1864, v. 14, p. 1-41, pi. 1-5.)
25 Leydig, I?.
Zum feineren Ban der Ar-
thropoden.
(Muller's Archiv, 1855, p. 376-
45, pi. 15-18.)
* Claus, C. Grundzuge der Zoologic. 4te
Aufl. 1880.
27 Packard, A. S. Guide to the study of
insects . . . Salem, 1869, p. 520-521.
coleoptera, the literature of which I
have, as far as possible, seen and
studied.
The earliest mention that I have
found of scales on coleoptera isin 1762, by Geoffr~y,~~ who not only mentioned
scales on several curcdiodae, but
also noticed those of dermestidae and
scarabaeidae. The next notice of
scales of coleoptera is in 1773, by Dru- ry,29 in his description of Entimzi~
imperialism where he alludes to the
scales upon this species of cwculion-
idae. In 1777, Lindenberg30 figured
and briefly described E~timus imperi-
alis and the scales which render it so
brilliant. In 1780 the same author31 '
gave quite an extended description, ac-
companied by colored figures, of the
scales of Entimus. Lindenberg's last
paper is partly devoted to
a curious
consideration of the question why in-
sects and small animals, some of them
requiring a microscope to reveal their
beauty, were made even more beautiful
than larger animals. Since the above-
mentioned papers were published, many
--
28 Geoffroy, E. L. Histoire abregde des in- sectes qui se trouvent aux environs de Paris . . . v. I, 1762. [See especially p. 69, 78-79, 114, 115, 277, 282-283, 288. 289, 293, 293, 295 and 299.1
29 Drury.
Illustrations of natural history
. . . V. I, 1773.
30 Lindenberg. Beschreibung eines bra-
silischen Russelkafers. (Der Naturforscher, iotes Stuck, Halle, 1777, p. 86-87. fig.) 31 Lindenberg. Ausfuhrlichere Beschrei-
bung des . . . brasilischen Riisselkafers, nebst einigen Betrachtungen. (Der Naturforscher, 14tes Stuck, Halle, 1780, p. 211-220, fig.)



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6 PSYCHE. [Jan.-Feb. 1883.
popular descriptions and brief notes
upon the scales of coleoptei-a have been printed, especially in handbooks for
microscopists, but the important con-
tributions to the subject are in Dujar-
din's Manual for the micros~ope,~~ in
Desc hamps' Researches on the elytra
of coleopteragg and lastly in Fischer's
somewhat extensive dissertationg4 on the scales of coleoptera, published in 1846. Fischer's dissertation was based upon
a large collection of coleoptera of Eu-
rope, which he examined and consid-
ered by families. He classified the
scales of cwcz~Iz'onidae into four groups and made a fifth group of the kind of
scales found on Anthyenus. These
divisions will be considered later, in
connection with the form and structure
of the scales.
I will begin the descriptive part of
my paper with an explanation of the
hairs of CicZndeIa dorsalis, for I wish
to say a good deal about scale-like
hairs in this paper, since the scales
of coleoptera are simply flattened hairs of a more or less complex nature. In
the progress of this paper I hope to
be able to point out affinities, not pre- 32 Dujardin, F.
Nouveau manuel complet
de l'observateur au microscope.
Avec atlas,
Paris, 1843.
33 Deschamps, B. Recherches microsco-
piques sur l'organisation des dlytres des col6optferes. (Ann. sci. nat., 1845, s. 3, v. 3, P- 354-363-1
34 Fischer, L. H. Microscopische Unter-
suchungen uber die Kaferschuppen. Disser- tation . . . Freiburg, 1846, fig.
Reprint (Isis,
1846, v. 6, p. 401-421, fig.)
viou~l~noted, between hairs and scales
of coleoptera.
HAIRS OF CICINDELA DORSAIJS.
The white hairs which clothe the
sides of the thorax of C. do?-salis and
are abundant upon nearly all parts of
the under side of this insect, even upon its legs and upon some of its ~no~~th-
parts, owe their white color to the pres- ence of air in their interior.
In transverse section these hairs -
for they are scarcely flat enough to be
termed scales - are circular, ellipsoi-
dal (as in fig. I, d) or with a slight
tendency to be triangular. The central
Fig. I.
airs of Cicindela dorsalis: a, from thorax; b, same partly deprived of air; c, apical end of same; d, transverse section of same; e, basal end of same; g, hair from antenna. Enlargement: a, b and g, loo d lam. ; c, d and e, 300 diarn.
portion is a canal, about one-fourth the diameter of the whole hair, and is filled with air. This canal is surrounded by
very minute cavities forming a sort of
pith-like substance filled with air and
extending outward to the outer chiti-
nous covering of the hair. The cavi-




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Jan.-Feb. 1883.1 ~'S~'TJ~?E. 7
ties or interstices of the pith-like por- tion open into the central canal of
the hair, but are prevented from direct
communication with the outer air by
the thin sheath of chitin which forms
the outer covering of each hair. Each
hair is closed at the apex (fig. I, c)
by this outer, impervious chitin layer
and at its basal end (fig. I, e) by a thick- ening of the chitin sheath to such an
extent as to entirely close the central
canal, with its surrounding pith-like
substance, from the outer air. This
structure, together with the mode of
closing,' of the basal end, leaves the
nature of the development of the hair
very apparent. It is a closed sacciform
appendage of the external chitino~is cov- ering of the insect, as are the scales of lepido ptera, coleoptera and diptera.
The knob formed by the basal end (fig.
I, e) of the hair is inserted into a pit in the chitin covering of the insect,
almost exactly as the corresponding
part of the scales of other insects are
attached.
The structural points above described
were obtained in two ways; first, by
sectioning the hairs with the microtome, and, second. by carefully observing
under the microscope the action of dif-
ferent reagents on the hairs. I obtained a few good transverse sections of hairs
taken from the sides of the thorax, and, by examination of these sections, veri-
fied the existence of an open central
canal. Fig. I, 4 shows one of these
sections which was about 0.01 111111. in thickness and about 0.02 mm. in aver-
age diameter, drawn with the camera.
The expulsion of the air from these
hairs, when they were broken at any
point, was readily effected by chloro-
form or alcohol, and scarcely less readily by glycerin, by turpentin, or even by
water, but if the hair had not been in-
jured at any point the air was not driven out by any of these reagents, even after ev&-a1 days action. When the air has
been expelled from a hair, the latter be- comes transparent, and is colorless with directly transmitted light in all parts
except where the chitin is thickened to
close the base ; this chitin is slightly brown. By obliquely transmitted light,
obtained by Aubk's illuminating appar-
atus, the hairs which have been deprived of air exhibit a slightly bluish shade.
Fig. I, 6, represents a hair of which the distal end has been deprived of air, the part from x to y is partly deprived of
air and the basal portion is still filled with air. Sometimes, especially when
glycerin or turpentin is used to expel the air, a part of the air will remain col-
lected in the central canal (fig. I, x toy) quite a while after it has left the cavities of the pith-like portion. The clearly
defined outline of this column of air led to the suspicion of an open canal, the
presence of which was later proved by
sections.
The hairs from different parts of C.
dorsalts vary little in form and size.
Those from the thorax and from the un-
der side of the abdomen are club-shaped
(fig. I, a and 6), are from 0.28 to 0.35 mm. in length, and from 0.015 to 0.025
mm. in diameter. They taper gradually
and slightly from the middle toward




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8 PSYCHE. [Jan.-Fel-i. 1883.
both ends ; the apex is usually truncated (fig. I, c). The basal part forms a
slight neck just above the point of inser- tion (fig. I, e). These hairs are but
slightly curved, but are so inserted as to lie nearly flat on the surface of the insect. The hairs (fig. I, g) from the anten-
nae are the smallest of the white hairs
on C. dorsalis. They are only about
0.07 mm. long and scarcely 0.01 mm.
in diameter near the base, from which
they taper to their acute tip. Tne long- est hairs are those from the labial palpi, of which the second joint only is densely hairy. These hairs are from 0.30 to
0.50 mm. long, and about 0.015 mm. in
diameter near their base, from which
they taper gradually to a fine, acute
apex. They are considerably curved
and slenderly filiform.
Between and upon the hairs of this
beetle are yellow, amorpl~ous masses,
quite transparent, and apparently secre- ted from the surface of the insect, altho they may be remnants of some matrix in
which the hairs are packed during the
pupal state of the insect. Fischer men-
tions substances of apparently similar
nature in his disse~tation,~~ and Hagei~,~~ in 1882, further discusses them. These
masses on C. dorsalis often take heauti- fully clear impressions of the hairs
themselves, and are insoluble in water,
alcohol, turpentin, glycerin or cl~loro- form.
With the exception of the elytra, lab-
rum and parts of the mandibles, all
30 Hagen, H. A. On the color and the
pattern of insects. (Proc. Amer. acad. arts and sciences, 1882, v. 17, p. 234-267.)
white portions of C. dorsalis owe their
creamy whiteness to the hairs described
above ; these hairs are set on shining,
cupreous or green-bronze surfaces.
The hairs upon the sides of the thorax
of C. vulgaris and C. $ziritana are
similar in structure and general form to hairs from the same region in C. dor-
saZis, but they are smaller in C. $un7am (0.18 mm. long by 0.01 mm. in diam-
eter) and slimmer in C. vz~lgaris (0.55
mm. long and about 0.01 mm. in diam-
eter) ; in the latter species they are not so abundant.
Taking the families of coleoptera in
their systematic order, I examined next
the scales of
ANTI-IRENUS SCROPHULARIAE.
The figuration of the whole body and
even of the legs of this insect is due to