Contributions to the larval history of Pacific Coast Coleoptera

AGRtC. DEP

BIOLOGY

LIBRARY

G

CONTRIBUTIONS

TO THE

BY

J. J. RIVERS,

Curator of the Museum, University of California.

STATE OFFICE

SACRAMENTO:

JAMES J. AYERS, SUPT. STATE PRINTING.

1886.

CONTRIBUTIONS

LARViL HE!

BY

J. J. RIVERS,

Curator of the Museum, University of California.

SACRAMENTO:

STATE OFFICE JAMES J. AYERS, SUPT. STATE PRINTING.

1886.

Mainlib7

AGftlC. D€PT,

CONTRIBUTIONS

TO THE

LARVAL HISTORY OF PACIFIC COAST COLEOPTERA.

By J. J. RIVERS, Curator of the Museum, University of California.

The study of systematic entomology affords the student but a dim idea
of what insects are noxious and what are innoxious. The distinctive char-
acters upon which the systematic entomologist builds classification need
not be and generally are not the characters of prime importance to the
economic entomologist. The names of many of the groups of Coleoptera
afford a slight generalized description which is often misleading. In the
present state of entomologic science, where systematic method is given
precedence over the biologic, it is dangerous to attempt to make a general
statement of the habits of a single genus, and impossible to generalize the
habits of a group or family.

The most valuable contribution to the life history of American insects
which is generally accessible is Dr. Packard's " Insects Injurious to Forest
and Shade Trees." * In his introduction , the author states that this work
is purely tentative, and designed^) elicit the results of the observations of
students of economic entomology. It is on that account that I feel at lib-
erty to comment upon or question certain of Dr. Packard's statements.

On page 118, op. cit: Prionus laticollis, Drury, is noted as injurious to
the poplar. If Prionus destroys living trees in other parts of America, it
has no such destructive habit in California; in fact, the charge against
borers that they destroy trees is a very old one, but by no means substan-
tiated by my own observations. P. Californicus goes through its trans-
formations in the roots of oaks, but these roots were dead in every case
observed by me, and usually belonged to stumps whose trunks had been
felled years before. Last year I bred several from the decayed part of an
old oaken chopping block. In fact, Dr. Packard himself throws some
doubt upon the destructive habit of P. latiocollis, for in his note he quotes
the report for 1872 of Prof. S. J. Smith, Entomologist to the Connecticut
Board of Agriculture, as follows: " I have noticed it in logs of poplar, bass-
wood, and oak, and in the trunks of old, decaying apple trees."

On page 137, op. cit., is the following: "We have found Buprestid and
Longicorn borers in a dead sweet gum tree." The caption at the head of
the page, " Insects Injurious to the Sweet Gum," seems designed to lead to
the inference that these borers killed the tree. But my observation is that
the larvae of insects of the two families noted feed only on dead wood.

Again, on the same page (137), Ptilinus basalis and Micracis hirtella
are listed as injurious to the California bay. These species are both found
in Berkeley, and I have observed their habits for the last seven years, and
as a result of such observation I am in a position to assert that they bore
into the twigs of the tree mentioned only when dead, dried, and decaying.

On page 71, op. cit., we find a figure of Oncideres cingulatus in the act
of girdling a hickory twig. In connection with this insect we meet with

*U.S. Entomological Commission, JMfetm V^Sington, 1881.

one of the most interesting and remarkable points in the whole range of
insect biology. For, knowing that its . larva will have to feed upon dead
and sapless wood, this beetle, at the time of depositing its egg in the living
and easily penetrated green wood, has instinct or forethought to girdle the
twig, and thus assure the future larva the conditions necessary for its
metamorphosis.

The question, "Are Curculio larva lignivorous ?" has been partially dis-
cussed in Bulletin of the Brooklyn Entomological Society, vol. vii, p. 150,
by Warren Knaus, and in Entomologica Americana, vol. i, p. 18, by W. H.
Harrington. The question was brought up by the finding of Wollostonia
quercicola in cottonwood logs in an advanced stage of decay. The Curcu-
lios are a group of insects in systematic value the equivalent to a sub-order,
and known as the Rynchophora (Latreille), which bear certain intimate
resemblance to one another in the perfect and final forms, while in their
larval stage they may, and certainly do, differ in many particulars of habit.
W. quercicola belongs to the Calandridae, a family abounding in species
whose habit in the larval stage is preeminently to feed on dry wood. The
metamorphoses of the Rhynchophora (Latr.) are not at all well known,
but I have bred the following, belonging to this sub-order, and have found
them to be lignivorous in the larval stage:

PLATYRHINUS LATIROSTRIS Fabr. — Decaying oak stumps highly charged
with mycelia of a fungus.

SCOLYTUS DESTRUCTOR Oliv. — Dead sapwood of elm.
MESITIS TARDII Woll. — Decaying beech.
MONARTHRUM HuTTONi Woll. — Various hard woods.
HYLESINUS CRENATUS Fabr. — Dying ash.
ANTHRIBUS ALBINUS Lin. — Old wood.
BRACHYTARSUS SCABROSUS Fabr. — Elm bark.
RYNCOLUS — several species. — Bark of trees.

The foregoing are old world species of Curculios that do not affect a
herbaceous diet; and the three following species are of similar habits.

SCOLYTIDJE.

MONARTHRUM SCUTELLARE Lee. — Bark of dead Quercus agrifolia.
MONARTHRUM DENTIGERUM Lee. — Bark of dead Quercus agrifolia.

MICRACIS HIRTELLA Lee. — Dead branches of California laurel, Umbellu-
laria Californica.

The Brenthidae are well known to have the general habit of perforating
trees and of depositing a single egg in each hole thus made, by this means
providing that the larva shall have a full supply of the wood upon which
it feeds.

The question, then, should not be: are Curculio larva? lignivorous? but
rather, how many have that habit? . In a great group like this of Curculios,
comprising many forms varying greatly from one another, one can easily
appreciate the fact that we meet with many different tastes and habits.

Some are known to feed upon all kinds of grain in store; one finds its food
in rice, another in barley, and others in maize. Many species of Balanius
undergo their changes in nuts, the larva feeding upon the kernels; another
group is to be found in Cynips galls; and one species, geographically dis-
tributed from San Diego to Alaska, is to be found beneath seaweed upon
the shores. Enough has been instanced to show clearly that we can draw
no inference from the fact that two insects are found in the same natural
group, that for that reason their habits are similar; and it is evident that a
classification by habits would be of little aid to the systematic entomologist.

CHRYSOMELID^E.

DIABROTICA soRO^Lec. — This is a most destructive insect to our peach
orchards, and is. not as yet sufficiently studied. If it resembles in habit
the eastern species of the genus, and feeds in the larva stage upon the roots
of cereals, it may be possible to rid ourselves in some degree of this pest
by some rotation of crops. In the meanwhile sprays and washes are beyond
a doubt not only useless, but in most cases a positive injury. We shall
have to study further before speaking positively of the larval history of this
insect pest.

PTINID^E.

PTINUS INTERRUPTUS Lee. — Black fungus of the laurel, Umbellularia
Californica.

PTINUS QUADRIMACULATUS Melsh. — Decayed Ceanothus thyrsiflorus.
HEDOBIA GRANOSA Lee. — Dead branches of Umbellularia Californica.

HADOBREGMUS GIBBICOLLIS Lee. — Decaying wood of Myrica Californica
and dead willow.

VRILLETTA CONVEX A Lee. — Dead Quercus agrifolia.

PTILINUS BASALTS Lee. — Dead twigs of Umbellularia Californica.

SINOXYLON DECLIVE Lee. — Any dead tree or unpainted wood, very partial
to wine casks and oak barrels. The depredations are done by the beetle
while boring for a suitable place to deposit its eggs. Its burrow is straight
across the grain of the wood, reaching the interior of the cask, causing
waste and deterioration of the contents. Hot solution of alum applied to
the outside of the casks will prevent boring.

POLYCAON STOUTII Lee. — Dead and dried willow.

POLYCAON CONFERTUS Lee. — Found boring into a slab of chestnut oak
that had been deposited for years in the museum of the University of Cali-
fornia; also bred from the stem of dead apricot trees that had been grafted
on a peach root.

There appears strong evidence that these trees were not destroyed by the
borer, but through the influence of the "black knot" on the roots, they
being diseased with knobs as large as a man's fist on every root; while all
the trees killed had the root diseased, only a portion was infested with the
larva of this beetle.

During July, while on a visit to the Napa Valley, I saw a lot of roots
and stems of grapevines that had been grubbed the year before. These
were old vines, and had been discarded on account of splitting of the main
stem. On examination these were found to contain both the worm and

6

the beetle forms of Polycaon confertus, showing that the metamorphosis
takes place in dead wood.

Many similar observations made by myself and others go to show that
in the larval stage this insect is xylophagous. On the other hand, there is
indisputable proof that the beetle infests living trees by entering the twigs
at the axils of the leaves.

LYCTUS STRIATUS Melsh. — Devastates furniture made of California laurel,
Umbellularia Californica, Dr. Packard, op. cit. p. 75, quotes Dr. LeConte
as saying that it affects the trunks and branches of Carya tomentosa. This
is not borne out by my observations, as I am well satisfied that the larva
lives in dead and dry wood.

SCARAB^EID^E.

POLYPHYLLA DECEMLiNEATA Say. — Larva that produced this species was
found in the earth from one to two feet from the surface, among root fibers
of a coarse grass and roots of a California laurel, Umbellularia Californica.
The earth was sandy loam situated upon the banks of a river, and which
is overflowed during the rainy season of the year.

ODONTAEUS OBESUS Lee. — This has a light chestnut larva with tufts of
bristles surrounding each spiracle. Mandibular and clypeal portions well
developed, redder in color, and thicker in texture than any other part.
The legs are prominent. Feed upon rootlets of Umbellularia Californica.
It is much infested with a small, pale-colored mite, which is evidently par-
asitic on the species.

LUCANID^E.

PLATYCERUS OREGONENSIS (Westwood). — Dead trees of Photinia arbuti-
folia, Umbellularia Californica, Quercus agrifolia, and Eucalyptus.

PLATYCERUS AGASSII Lee. — Decayed trees of Arbutus Menziesii; also in
wood too much decayed to be identified.

SINODENDRON RUGOSUM Mann. — Decayed oak, Quercus agrifolia.

The five hundred and twenty-two North American species of Ceramby-
cidse are all borers; the insect deposits its egg in a hole perforated in the
wood, and the larva penetrates further and further according to a rhyth-
mic order peculiar to the species until its metamorphoses are completed.
The following is a list of the Californian species whose habits I have
observed:

CERAMBYCimE.

ERGATES SPICULATUS Lee. — Rotting coniferous trees. Bred from Sequoia
sempervirens, Pinus insignis, Abies Douglasii, etc.

PRIONUS CALIFORNICUS Mots. — Bred from rotten damp roots of Quercus
agrifolia.

ASEMUM NITIDUM Lee. — Decayed Pinus insignis.

HYLOTRUPES LIGNEUS Fab. — Dead trees of Libocedrus decurrens.

ELAPHIDION IMBELLE Lee. — Bred from decayed oak near San Diego, Cal.,
by F. E. Blaisdell.

HOLOPLEURA HELENA Lee. — Dead twigs of Umbellularia Californica.

ROSALIA FUNEBRIS Mots. — Decaying Umbellularia Californica among
the mycelia of some fungus.

XYLOTRICHUS NAUTICUS Mann. — Dead sapwood of the oak, Quercus agri-
folia.

XYLOTRECHUS OBLITKRATUS Lee., insignis F. — Dead branches of willow.

NECYDALIS L^EVICOLLIS Lee. — Decayed oak, Quercus agrifolia, and in
dead Eucalyptus globulus.

LEPTURA L^ETA Lee. — Dead Quercus agrifolia and Quercus sp.
LEPTURA GRASSIPES Lee. — Decayed wood of Umbellularia Californica.

SYNAPHCETA GUEXI Lee. — Dead limbs of California buckeye, JEsculus
Californica.

POGONOCHERUS CRiNiTUS Lee. — Dead branches of Quercus agrifolia.

TROGOSITID.E.

TROGOSITA VIRESCENS Fab. — Dead Libocedrus and several kinds of oak.

CLERID^E.

THANASIMUS EXTMIUS Mann. — Dead twigs of Umbellularia Californica.

MELANDRYID^E.

RIVERSII Lec. — Larva feeds in decaying trees of Madroria,
Arbutus Menziesii. In trees in position the insect is found in the primary
forks of the roots, and in prostrate logs among the more seasoned fibers of
the wood.

LAMPYRID^E.

Among many entomological enigmas of long standing is one that is about
being solved. From time to time in many parts of the United States, large
luminous larvae of some Coleopteron have been found, and it has been con-
jectured that these larvae belong to some of the Elateridae, the general
supposition being that they were larvae of the genus Melanactes. Every
attempt at breeding them resulted in failure because their natural food
was unknown. I have recently found what their food consists of. Before
making this discovery I had arrived, from a careful study of the anatomy
of the mouth parts of these larvae, at the conclusion now confirmed, that
they are carnivorous in habit.

Their food consists of the vegetable feeding Myriapoda, particularly of
Julus and Polydesmus, with a preference for Julus, because the large area
of the rings of this genus affords space for the larva to penetrate the interior
of the Myriapod. Its manner of feeding is to seize the hinder part of the
Julus, and perforate a segment, reaching the soft inner parts, which it
devours at leisure, creeping through many segments without disjointing
them, and remaining inside these rings for days at a time, till one can
see little else but the slowly wriggling form of the dying Julus.

I have a full fed larva, which I hope will go through its metamorphosis,
and solve the problem. And now its mode of life is made known, other
persons who are equally anxious with myself that nature shall yield this

8

long kept secret, can apply themselves with renewed energy to the task of
discovering the identity of the perfect insect.

This luminous larva has proved to be the form of the female in a Lam-
pyrid beetle, better known as Zarhipis Riversi Horn. Or if not a perfectly
metamorphosed female, possesses the powers of that sex to produce ova
and attract the male. The grub or larva had fed all winter, and in March
sloughed its skin and remained motionless, coiled in a cell of earth, for
three weeks, and kept a uniform pale-cream color without luminosity, but
gradually the center of the dorsal plates became darker, and in the ratio
of coloring so was the reappearance of the phosphorescent light; when fully
restored in strength it became very active and strongly luminous, but it did
not eat. In about a week ft disappeared beneath the earth, and remained
out of sight for nearly a month, and thinking it had changed into the pupa
state I disturbed it, and found no change to have taken place. I returned
it to the jar, placing the coiled insect upon the top of the earth, where it lay
motionless for two days. On the morning of the third day I found it had
sloughed another skin, but this time a very. thin covering of uniform pale
brown, and the insect itself had disappeared into the earth. This last dor-
mant stage seems to represent its pupa state. I unearthed it again and
found it very soon afterwards to assume great activity and bright lumin-
osity, but it would take none of the usual food. Taking the jar which con-
tained this insect into the open air for the purpose of supplying it with fresh
earth, and while doing so, several male specimens came flying around the
jar, and one example dropped swiftly upon what had been supposed to be
the larval form. The male soon attempted copulation. The attraction of
the female was perfect, and by it I captured eleven males. The eleven
males attracted were not all of the form known as Z. River si Horn, some
represent the Z. piciventris Lee., and these facts will cause a revision of the
genus, and the four species will be reduced one under the name of Zarhipis
integripennis Lee.

Description of a form of the female:

Apterous, vermiform, segmented, retractile, phosphorescent. Number
of joints, exclusive of the head, twelve. Legs, six; two on each of the
three anterior segments, or on those portions underneath representing the
pro, meso, and metasternum. Length, when extended in walking, two
and a quarter inches; and the width, across the widest part, five sixteenths
of an inch.

Head, corneous, shining black, and not well defined, and when at rest,
hidden beneath the anterior segment. The prominent character of the
head consists of a pair of curved, hook-like mandibles, like those of the
male. Antennae, short, straight, four-jointed; the apical joint bristle-like,
and growing from the side, at the end of the previous joint, which is the
largest, and tubular in form.

Maxillary palpi, five-jointed, four being nearly equal and bead-like.

Labial palpi appear two-jointed. The antennae and palpi being short,
stand stiffly out from their base.

Dorsal surface consists of twelve thin corneous plates, the three anterior
being narrowed in front, and all having an impressed line through the
longitudinal center. The plates are shining, blackish brown, marginal
transversely with transparent olive green, and upon the side margins with
opaque pale-yellow, interspersed with olive, which colors intermixed obtain
upon the sides arid under parts generally.

Spiracles upon the sides of the fourth to the eleventh segments, inclusive,
and just below the spiracles on the same segments is a double fold, form-

ing a broken lateral ridge. The other segments bear but a single fold and
no spiracles.

The thoracic region bearing the legs exhibits indistinct sutures and folds
presenting but a faint resemblance to analogous parts in other Coleoptera,
and yet is strongly of the Lampyrid type.

Legs of the Lampyrid type, four-jointed, and, like females of the group,
have a short obtuse tarsal claw.

This is a handsome insect when living, and is the most brilliant "glow-
worm " known. The light appears most intense on the cross margins of
the dorsal plates, but the luminosity is also strong on all the margins, as
well as along the lateral edges. Sometimes the insect appears checkered
by being banded with phosphorescence.

.There are some more facts to learn about this peculiar insect. Why the
larva should be luminous, and yet have nothing to attract; and why the
adult female should be luminous, while the male is not nocturnal, but
roams in the sunlight. The habit of the 'male is to appear on the wing, in
temperate heat, from 9 A. M. to 4 p. M., but during the hottest weather it
does not appear until the sun is declining.

Perhaps there is yet to be discovered another form of the female, without
luminosity, and perhaps more perfect in its parts, and non-luminous.

Some more questions are: What are the differences in the larval form
of the sexes, or, are there any larval differences of the sexes? The answers
to these queries will only come after observations; but the answer to the
one concerning the luminous character may give way to theory, and it may
be suggested that the luminous quality is inherited, and though without
use in this species because of the diurnal habit, yet may be a derived char-
acter that is only of use when the habit of the insect is nocturnal. But it
must be considered that the plumose antennae of the male would indicate
that it seeks its mate by scent.

This species is in no sense an injurious insect, but, on the contrary, may
be considered as beneficial to agriculture, having an entirely carnivorous
habit.

A NEW SPECIES OF CALIFORNIAN COLEOPTERA.

By J. J. RIVERS, Curator of Museum, University of California.

BBADYCINETUS, HORN.

Bradycinetus Hornii, n. sp.

Male: Form, robust, elliptical. Color, ferruginous
brown, shining; head, tips of armature, margins of pro-
thorax, and a spot near the outer margin of prothorax,
either dusky or black. Head: Clypeus transverse and
feebly angulate at the sides, the front edge
rising increasingly backward, until just be-
fore reaching the clypeal suture it ends in
a well formed tubercle on either side; be-
Male. hind the sutural line on the vertex is a

very prominent, stout, conical horn; three fourths of the lower portion of
the horn and the whole of the frontal area finely rugose. Antennae:
funicle shining, chestnut; club paler, not shining. Thorax: subtriangular,
2

10

deepest longitudinally through the center; noticeably wider than the elytra
at their juncture, and rather wider than their greatest breadth; seen from
above the front margin appears truncate in the middle, then trends
obliquely forward to the angles which are prominent; sides straight for a
short distance, posterior angles strongly rounded; posterior margin much
extended in the middle with distinct sinuations toward the angles. The
front area deeply concave, surmounted with four well formed tubercles;
two occupying the center, bold and projecting over the concavity, two
others, one on either side of the central two situated near the anterior
margin of the thorax at its exterior angles. The area around the two
anterior tubercles very rugosely punctate ; and transversely across the disc
are large distinct punctures nowhere extending to the posterior margin. A
well defined margin, re flexed at the sides, surrounds the whole. Elytra:
very convex, obtusely rounded behind, having fourteen well defined and
regularly punctured striae, the interstices of which are flattened and indis-
tinctly wrinkled. The under side paler than the upper; dense fringes of
light chestnut hair line the reflexed portion of the thorax and elytra, while
the femora, tibia, and tarsal joints, as well as the lower side generally, are
well supplied with rather long chestnut hair. Length .48-. 52 inch.

Female: Form and color as in male. Labrum pro-
jecting, rugose, covering the mandibles. Head : clypeal
margin raised; a feeble tubercle just in front of the
clypeal suture, immediately behind which is a central
transverse ridge, undivided, slightly higher in the
middle and slightly apiculate at either end. Anten-
nae less robust than in the male. Thorax : very convex,
shining; outline obtusely triangular; anterior margin
Female. seen from above, truncate in the center; angles pro-

duced; sides rounded; posterior margin much produced to meet the scu-
tellum, sinuate toward the angles which are rounded; the front discal area
characterized by a bi-lobed transverse raised line, at either end of which,
outward and forward, is a well formed but ^ depressed tubercle; behind
which line the disc is dense with coarse corrugated punctures, which
become scattered and plain, nowhere reaching the posterior margin, but
taking a transverse course, barely reach the side margins, where they
become less distinct. - Elytra: much the same as in the male, but the
interstices of the fourteen punctate striae a trifle more wrinkled and much
more convex. Length, smaller than the male.

Habitat: burrowing in the ground near the City of Sonora, Tuolumne
County, California; found also in Sacramento County.

The name selected for this species is intended to be a small tribute of
honor to Dr. George H. Horn, the eminent Coleopterist, as a slight return
for many favors.

STRIDULATING ORGANS.

The sound of stridulating was first heard by Mr. Charles
Fuchs, of Alameda, who, having living specimens, made exam-
inations for the source of the sounds, and was rewarded by find-
ing the stridulating apparatus to be three bands situated one
each upon the fourth, fifth, and sixth dorsal segments, are well
developed, and when magnified show that these bands are set with bristles
in diagonal rows, the points of the bristles are bent downward, which, by
the quick contraction of the abdomen, these hooked bristles are brought
in repeated contact with the edge of the elytra arid thus causing the vibra-
tions known as stridulating.

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