COLCOTHAR (adapted in Romanic languages from Arabic _golgotar_, which
was probably a corruption of the Gr. [Greek: chalkanthos], from [Greek:
chalkos], copper, [Greek: anthos], flower, i.e. copper sulphate), a name
given to the brownish-red ferric oxide formed in the preparation of
fuming sulphuric (Nordhausen) acid by distilling ferrous sulphate. It is
used as a polishing powder, forming the rouge of jewellers, and as the
pigment Indian red. It is also known as _Crocus Martis_.
COLD (in O. Eng. _cald_ and _ceald_, a word coming ultimately from a
root cognate with the Lat. _gelu_, _gelidus_, and common in the Teutonic
languages, which usually have two distinct forms for the substantive and
the adjective, cf. Ger. _Kalte_, _kalt_, Dutch _koude_, _koud_),
subjectively the sensation which is excited by contact with a substance
whose temperature is lower than the normal; objectively a quality or
condition of material bodies which gives rise to that sensation. Whether
cold, in the objective sense, was to be regarded as a positive quality
or merely as absence of heat was long a debated question. Thus Robert
Boyle, who does not commit himself definitely to either view, says, in
his _New Experiments and Observations touching Cold_, that "the dispute
which is the _primum frigidum_ is very well known among naturalists,
some contending for the earth, others for water, others for the air, and
some of the moderns for nitre, but all seeming to agree that there is
some body or other that is of its own nature supremely cold and by
participation of which all other bodies obtain that quality." But with
the general acceptance of the dynamical theory of heat, cold naturally
came to be regarded as a negative condition, depending on decrease in
the amount of the molecular vibration that constitutes heat.
The question whether there is a limit to the degree of cold possible,
and, if so, where the zero must be placed, was first attacked by the
French physicist, G. Amontons, in 1702-1703, in connexion with his
improvements in the air-thermometer. In his instrument temperatures were
indicated by the height at which a column of mercury was sustained by a
certain mass of air, the volume or "spring" of which of course varied
with the heat to which it was exposed. Amontons therefore argued that
the zero of his thermometer would be that temperature at which the
spring of the air in it was reduced to nothing. On the scale he used the
boiling-point of water was marked at 73 and the melting-point of ice at
51-1/2, so that the zero of his scale was equivalent to about -240 deg.
on the centigrade scale. This remarkably close approximation to the
modern value of -273 deg. for the zero of the air-thermometer was
further improved on by J. H. Lambert (_Pyrometrie_, 1779), who gave the
value -270 deg. and observed that this temperature might be regarded as
absolute cold. Values of this order for the absolute zero were not,
however, universally accepted about this period. Laplace and Lavoisier,
for instance, in their treatise on heat (1780), arrived at values
ranging from 1500 deg. to 3000 deg. below the freezing-point of water,
and thought that in any case it must be at least 600 deg. below, while
John Dalton in his _Chemical Philosophy_ gave ten calculations of this
value, and finally adopted -3000 deg. C. as the natural zero of
temperature. After J. P. Joule had determined the mechanical equivalent
of heat, Lord Kelvin approached the question from an entirely different
point of view, and in 1848 devised a scale of absolute temperature which
was independent of the properties of any particular substance and was
based solely on the fundamental laws of thermodynamics (see HEAT and
THERMODYNAMICS). It followed from the principles on which this scale was
constructed that its zero was placed at -273 deg., at almost precisely
the same point as the zero of the air-thermometer.
In nature the realms of space, on the probable assumption that the
interstellar medium is perfectly transparent and diathermanous, must, as
was pointed out by W. J. Macquorn Rankine, be incapable of acquiring any
temperature, and must therefore be at the absolute zero. That, however,
is not to say that if a suitable thermometer could be projected into
space it would give a reading of -273 deg.. On the contrary, not being a
transparent and diathermanous body, it would absorb radiation from the
sun and other stars, and would thus become warmed. Professor J. H.
Poynting ("Radiation in the Solar System," _Phil. Trans._, A, 1903, 202,
p. 525) showed that as regards bodies in the solar system the effects of
radiation from the stars are negligible, and calculated that by solar
radiation alone a small absorbing sphere at the distance of Mercury from
the sun would have its temperature raised to 483 deg. Abs. (210 deg. C),
at the distance of Venus to 358 deg. Abs. (85 deg. C), of the earth to
300 deg. Abs. (27 deg. C), of Mars to 243 deg. Abs. (-30 deg. C), and of
Neptune to only 54 deg. Abs. (-219 deg. C.). The French physicists of
the early part of the 19th century held a different view, and rejected
the hypothesis of the absolute cold of space. Fourier, for instance,
postulated a fundamental temperature of space as necessary for the
explanation of the heat-effects observed on the surface of the earth,
and estimated that in the interplanetary regions it was little less than
that of the terrestrial poles and below the freezing-point of mercury,
though it was different in other parts of space (_Ann. chim. phys._,
1824, 27, pp. 141, 150). C. S. M. Pouillet, again, calculated the
temperature of interplanetary space as -142 deg. C. (_Comptes rendus_,
1838, 7, p. 61), and Sir John Herschel as -150 deg. (_Ency. Brit._, 8th
ed., art. "Meteorology," p. 643).
To attain the absolute zero in the laboratory, that is, to deprive a
substance entirely of its heat, is a thermodynamical impossibility, and
the most that the physicist can hope for is an indefinitely close
approach to that point. The lowest steady temperature obtainable by the
exhaustion of liquid hydrogen is about -262 deg. C. (11 deg. Abs.), and
the liquefaction of helium by Professor Kamerlingh Onnes in 1908 yielded
a liquid having a boiling-point of about 4.3 deg. Abs., which on
exhaustion must bring us to within about 2-1/2 degrees of the absolute
zero. (See LIQUID GASES.)
For a "cold," in the medical sense, see CATARRH and Respiratory
System: _Pathology_.
COLDEN, CADWALLADER (1688-1776), American physician and colonial
official, was born at Duns, Scotland, on the 17th of February 1688. He
graduated at the university of Edinburgh in 1705, spent three years in
London in the study of medicine, and emigrated to America in 1708. After
practising medicine for ten years in Philadelphia, he was invited to
settle in New York by Governor Hunter, and in 1718 was appointed the
first surveyor-general of the colony. Becoming a member of the
provincial council in 1720, he served for many years as its president,
and from 1761 until his death was lieutenant-governor; for a
considerable part of the time, during the interim between the
appointment of governors, he was acting-governor. About 1755 he retired
from medical practice. As early as 1729 he had built a country house
called Coldengham on the line between Ulster and Orange counties, where
he spent much of his time until 1761. Aristocratic and extremely
conservative, he had a violent distrust of popular government and a
strong aversion to the popular party in New York. Naturally he came into
frequent conflict with the growing sentiment in the colony in opposition
to royal taxation. He was acting-governor when in 1765 the stamped paper
to be used under the Stamp Act arrived in the port of New York; a mob
burned him in effigy in his own coach in Bowling Green, in sight of the
enraged acting-governor and of General Gage; and Colden was compelled to
surrender the stamps to the city council, by whom they were locked up
in the city hall until all attempts to enforce the new law were
abandoned. Subsequently Colden secured the suspension of the provincial
assembly by an act of parliament. He understood, however, the real
temper of the patriot party, and in 1775, when the outbreak of
hostilities seamed inevitable, he strongly advised the ministry to act
with caution and to concede some of the colonists' demands. When the war
began, he retired to his Long Island country seat, where he died on the
28th of September 1776. Colden was widely known among scientists and men
of letters in England and America. He was a life-long student of botany,
and was the first to introduce in America the classification system of
Linnaeus, who gave the name "Coldenia" to a newly recognized genus. He
was an intimate friend of Benjamin Franklin. He wrote several medical
works of importance in their day, the most noteworthy being _A Treatise
on Wounds and Fevers_ (1765); he also wrote _The History of the Five
Indian Nations depending on the Province of New York_ (1727, reprinted
1866 and 1905), and an elaborate work on _The Principles of Action in
Matter_ (1751) which, with his _Introduction to the Study of Physics_
(c. 1756), his _Enquiry into the Principles of Vital Motion_ (1766), and
his _Reflections_ (c. 1770), mark him as the first of American
materialists and one of the ablest material philosophers of his day. I.
Woodbridge Riley, in _American Philosophy_ (New York, 1907), made the
first critical study of Colden's philosophy, and said of it that it
combined "Newtonian mechanics with the ancient hylozoistic doctrine ..."
and "ultimately reached a kind of dynamic panpsychism, substance being
conceived as a self-acting and universally diffused principle, whose
essence is power and force."
See Alice M. Keys, _Cadwallader Colden, A Representative 18th Century
Official_ (New York, 1906), a Columbia University doctoral
dissertation; J. G. Mumford, _Narrative of Medicine in America_ (New
York, 1903); and Asa Gray, "Selections from the Scientific
Correspondence of Cadwallader Colden" in _American Journal of
Science_, vol. 44, 1843.
His grandson, CADWALLADER DAVID COLDEN (1769-1834), lawyer and
politician, was educated in London, but returned in 1785 to New York,
where he attained great distinction at the bar. He was a colonel of
volunteers during the war of 1812, and from 1818 to 1821 was the
successor of Jacob Radcliff as mayor of New York City. He was a member
of the state assembly (1818) and the state senate (1825-1827), and did
much to secure the construction of the Erie Canal and the organization
of the state public school system; and in 1821-1823 he was a
representative in Congress. He wrote a _Life of Robert Fulton_ (1817)
and a _Memoir of the Celebration of the Completion of the New York
Canals_ (1825).
COLD HARBOR, OLD and NEW, two localities in Hanover county, Virginia,
U.S.A., 10 m. N.E. of Richmond. They were the scenes of a succession of
battles, on May 31-June 12, 1864, between the Union forces under command
of General U. S. Grant and the Confederates under General R. E. Lee, who
held a strongly entrenched line at New Cold Harbor. The main Union
attack on June 3 was delivered by the II. (Hancock), VI. (Wright), and
XVIII. (W. F. Smith) corps, and was brought to a standstill in eight
minutes. An order from army headquarters to renew the attack was ignored
by the officers and men at the front, who realized fully the strength of
the hostile position. These troops lost as many as 5,000 men in an
hour's fighting, the greater part in the few minutes of the actual
assault. In the constant fighting of 31st of May to 12th of June on this
ground Grant lost 14,000 men. (See WILDERNESS and AMERICAN CIVIL WAR.)
COLDSTREAM, a police burgh of Berwickshire, Scotland. Pop. (1901) 1482.
It is situated on the north bank of the Tweed, here spanned by John
Smeaton's fine bridge of five arches, erected in 1763-1766, 13-1/2 m.
south-west of Berwick by the North Eastern railway. The chief public
buildings are the town hall, library, mechanics' institute, and cottage
hospital. Some brewing is carried on. Owing to its position on the
Border and also as the first ford of any consequence above Berwick, the
town played a prominent part in Scottish history during many centuries.
Here Edward I. crossed the stream in 1296 with his invading host, and
Montrose with the Covenanters in 1640. Of the Cistercian priory, founded
about 1165 by Cospatric of Dunbar, and destroyed by the 1st earl of
Hertford in 1545, which stood a little to the east of the present
market-place, no trace remains; but for nearly four hundred years it was
a centre of religious fervour. Here it was that the papal legate, in the
reign of Henry VIII., published a bull against the printing of the
Scriptures; and by the irony of fate its site was occupied in the 19th
century by an establishment, under Dr Adam Thomson, for the production
of cheap Bibles. At Coldstream General Monk raised in 1659 the
celebrated regiment of Foot Guards bearing its name. Like Gretna Green,
Coldstream long enjoyed a notoriety as the resort of runaway couples,
the old toll-house at the bridge being the usual scene of the marriage
ceremony. "Marriage House," as it is called, still exists in good
repair. Henry Brougham, afterwards lord chancellor, was married in this
clandestine way, though in an inn and not at the bridge, in 1821.
Birgham, 3 m. west, was once a place of no small importance, for there
in 1188 William the Lion conferred with the bishop of Durham concerning
the attempt of the English Church to impose its supremacy upon Scotland;
there in 1289 was held the convention to consider the question of the
marriage of the Maid of Norway with Prince Edward of England; and there,
too, in 1290 was signed the treaty of Birgham, which secured the
independence of Scotland. Seven miles below Coldstream on the English
side, though 6 m. north-east of it, are the massive ruins of Norham
Castle, made famous by Scott's _Marmion_, and from the time of its
building by Ranulph Flambard in 1121 a focus of Border history during
four centuries.
COLDWATER, a city and county-seat of Branch county, Michigan, U.S.A., on
Coldwater Stream (which connects two of the group of small lakes in the
vicinity), about 80 m. S.S.E. of Grand Rapids. Pop. (1890) 5247; (1900)
6216, of whom 431 were foreign-born; (1904) 6225; (1910) 5945. It is
served by the Lake Shore & Michigan Southern railway. It is the seat of
a state public school and temporary home (opened in 1874) for dependent,
neglected or ill-treated children, who are received at any age under
twelve. The city is situated in a fine farming region, has an important
flouring and grist mill industry, and also manufactures Portland cement,
liniment, lumber, furniture, sashes, doors and blinds, brass castings,
sleighs, shoes, &c. The municipality owns and operates the water-works
and electric lighting plant. Coldwater was settled in 1829, was laid out
as a town under the name of Lyons in 1832, received its present name in
the following year, was incorporated as a village in 1837, was reached
by railway and became the county-seat in 1851, and was chartered as a
city in 1861.
COLE, SIR HENRY (1808-1882), English civil servant, was born at Bath on
the 15th of July 1808, and was the son of an officer in the army. At the
age of fifteen he became clerk to Sir Francis Palgrave, then a
subordinate officer in the record office, and, helped by Charles Buller,
to whom he had been introduced by Thomas Love Peacock, and who became
chairman of a royal commission for inquiry into the condition of the
public records, worked his way up until he became an assistant keeper.
He largely assisted in influencing public opinion in support of Sir
Rowland Hill's reforms at the post office. A connexion with the Society
of Arts caused him to drift gradually out of the record office: he was a
leading member of the commission that organized the Great Exhibition of
1851, and upon the conclusion of its labours was made secretary to the
School of Design, which by a series of transformations became in 1853
the Department of Science and Art. Under its auspices the South
Kensington (now Victoria and Albert) Museum was founded in 1855 upon
land purchased out of the surplus of the exhibition, and Cole
practically became its director, retiring in 1873. His proceedings were
frequently criticized, but the museum owes much to his energy.
Indefatigable, genial and masterful, he drove everything before him, and
by all sorts of schemes and devices built up a great institution, whose
variety and inequality of composition seemed imaged in the anomalous
structure in which it was temporarily housed. He also, though to the
financial disappointment of many, conferred a great benefit upon the
metropolis by originating the scheme for the erection of the Royal
Albert Hall. He was active in founding the national training schools for
cookery and music, the latter the germ of the Royal College of Music. He
edited the works of his benefactor Peacock; and was in his younger days
largely connected with the press, and the author of many useful
topographical handbooks published under the pseudonym of "Felix
Summerly." He died on the 18th of April 1882.
COLE, THOMAS (1801-1848), American landscape painter, was born at
Bolton-le-Moors, England, on the 1st of February 1801. In 1819 the
family emigrated to America, settling first in Philadelphia and then at
Steubenville, Ohio, where Cole learned the rudiments of his profession
from a wandering portrait painter named Stein. He went about the country
painting portraits, but with little financial success. Removing to New
York (1825), he displayed some landscapes in the window of an
eating-house, where they attracted the attention of the painter Colonel
Trumbull, who sought him out, bought one of his canvases, and found him
patrons. From this time Cole was prosperous. He is best remembered by a
series of pictures consisting of four canvases representing "The Voyage
of Life," and another series of five canvases representing "The Course
of Empire," the latter now in the gallery of the New York Historical
Society. They were allegories, in the taste of the day, and became
exceedingly popular, being reproduced in engravings with great success.
The work, however, was meretricious, the sentiment false, artificial and
conventional, and the artist's genuine fame must rest on his landscapes,
which, though thin in the painting, hard in the handling, and not
infrequently painful in detail, were at least earnest endeavours to
portray the world out of doors as it appeared to the painter; their
failings were the result of Cole's environment and training. He had an
influence on his time and his fellows which was considerable, and with
Durand he may be said to have founded the early school of American
landscape painters. Cole spent the years 1829-1832 and 1841-1842 abroad,
mainly in Italy, and at Florence lived with the sculptor Greenough.
After 1827 he had a studio in the Catskills which furnished the subjects
of some of his canvases, and he died at Catskill, New York, on the 11th
of February 1848. His pictures are in many public and private
collections. His "Expulsion from Eden" is in the Metropolitan Museum in
New York.
COLE, TIMOTHY (1852- ), American wood engraver, was born in London,
England, in 1852, his family emigrating to the United States in 1858. He
established himself in Chicago, where in the great fire of 1871 he lost
everything he possessed. In 1875 he removed to New York, finding work on
the _Century_ (then _Scribner's_) magazine. He immediately attracted
attention by his unusual facility and his sympathetic interpretation of
illustrations and pictures, and his publishers sent him abroad in 1883
to engrave a set of blocks after the old masters in the European
galleries. These achieved for him a brilliant success. His reproductions
of Italian, Dutch, Flemish and English pictures were published in book
form with appreciative notes by the engraver himself. Though the advent
of new mechanical processes had rendered wood engraving almost a lost
art and left practically no demand for the work of such craftsmen, Mr
Cole was thus enabled to continue his work, and became one of the
foremost contemporary masters of wood engraving. He received a medal of
the first class at the Paris Exhibition of 1900, and the only grand
prize given for wood engraving at the Louisiana Purchase Exposition at
St Louis, Missouri, in 1904.
COLE, VICAT (1833-1893), English painter, born at Portsmouth on the 17th
of April 1833, was the son of the landscape painter, George Cole, and in
his practice followed his father's lead with marked success. He
exhibited at the British Institution at the age of nineteen, and was
first represented at the Royal Academy in 1853. His election as an
associate of this institution took place in 1870, and he became an
Academician ten years later. He died in London on the 6th of April 1893.
The wide popularity of his work was due partly to the simple directness
of his technical method, and partly to his habitual choice of attractive
material. Most of his subjects were found in the counties of Surrey and
Sussex, and along the banks of the Thames. One of his largest pictures,
"The Pool of London," was bought by the Chantrey Fund Trustees in 1888,
and is now in the Tate Gallery.
See Robert Chignell, _The Life and Paintings of Vicat Cole, R.A._
(London, 1899).
COLEBROOKE, HENRY THOMAS (1765-1837), English Orientalist, the third son
of Sir George Colebrooke, 2nd baronet, was born in London on the 15th of
June 1765. He was educated at home; and when only fifteen he had made
considerable attainments in classics and mathematics. From the age of
twelve to sixteen he resided in France, and in 1782 was appointed to a
writership in India. About a year after his arrival there he was placed
in the board of accounts in Calcutta; and three years later he was
removed to a situation in the revenue department at Tirhut. In 1789 he
was removed to Purneah, where he investigated the resources of that part
of the country, and published his _Remarks on the Husbandry and Commerce
of Bengal_, privately printed in 1795, in which he advocated free trade
between Great Britain and India. After eleven years' residence in India,
Colebrooke began the study of Sanskrit; and to him was confided the
translation of the great _Digest of Hindu Laws_, which had been left
unfinished by Sir William Jones. He translated the two treatises
_Mitacshara_ and _Dayabhaga_ under the title _Law of Inheritance_. He
was sent to Nagpur in 1799 on a special mission, and on his return was
made a judge of the new court of appeal, over which he afterwards
presided. In 1805 Lord Wellesley appointed him professor of Hindu Law
and Sanskrit at the college of Fort William. During his residence at
Calcutta he wrote his _Sanskrit Grammar_ (1805), some papers on the
religious ceremonies of the Hindus, and his _Essay on the Vedas_ (1805),
for a long time the standard work on the subject. He became member of
council in 1807 and returned to England seven years later. He died on
the 18th of March 1837. He was a director of the Asiatic Society, and
many of the most valuable papers in the society's _Transactions_ were
communicated by him.
His life was written by his son, Sir T. E. Colebrooke, in 1873.
COLEMANITE, a hydrous calcium borate, Ca2B6O11 + 5H2O, found in
California as brilliant monoclinic crystals. It contains 50.9% of boron
trioxide, and is an important source of commercial borates and boracic
acid. Beautifully developed crystals, up to 2 or 3 in. in length,
encrust cavities in compact, white colemanite; they are colourless and
transparent, and the brilliant lustre of their faces is vitreous to
adamantine in character. There is a perfect cleavage parallel to the
plane of symmetry of the crystals. Hardness 4-4-1/2; specific gravity
2.42. The mineral was first discovered in 1882 in Death Valley, Inyo
county, California, and in the following year it was found in greater
abundance near Daggett in San Bernardino county, forming with other
borates and borosilicates a bed in sedimentary strata of sandstones and
clays; in more recent years very large masses have been found and worked
in these localities, and also in Los Angeles county (see Special Report,
1905, of U.S. Census Bureau on _Mines and Quarries_; and _Mineral
Resources of the U.S._, 1907).
Priceite and pandermite are hydrous calcium borates with very nearly the
same composition as colemanite, and they may really be only impure forms
of this species. They are massive white minerals, the former friable and
chalk-like, and the latter firm and compact in texture. Priceite occurs
near Chetco in Curry county, Oregon, where it forms layers between a bed
of slate and one of tough blue steatite; embedded in the steatite are
rounded masses of priceite varying in size from that of a pea to masses
weighing 200 lb. Pandermite comes from Asia Minor, and is shipped from
the port of Panderma on the Sea of Marmora: it occurs as large nodules,
up to a ton in weight, beneath a thick bed of gypsum.
Another borate of commercial importance found abundantly in the
Californian deposits is ulexite, also known as boronatrocalcite or
"cotton-ball," a hydrous calcium and sodium borate, CaNaB5O9 + 8H2O,
which forms rounded masses consisting of a loose aggregate of fine
fibres. It is the principal species in the borate deposits in the
Atacama region of South America. (L. J. S.)
COLENSO, JOHN WILLIAM (1814-1883), English bishop of Natal, was born at
St Austell, Cornwall, on the 24th of January 1814. His family were in
embarrassed circumstances, and he was indebted to relatives for the
means of university education. In 1836 he was second wrangler and
Smith's prizeman at Cambridge, and in 1837 he became fellow of St
John's. Two years later he went to Harrow as mathematical tutor, but the
step proved an unfortunate one. The school was just then at the lowest
ebb, and Colenso not only had few pupils, but lost most of his property
by a fire. He went back to Cambridge, and in a short time paid off heavy
debts by diligent tutoring and the proceeds of his series of manuals of
algebra (1841) and arithmetic (1843), which were adopted all over
England. In 1846 he became rector of Forncett St Mary, Norfolk, and in
1853 he was appointed bishop of Natal. He at once devoted himself to
acquiring the Zulu language, of which he compiled a grammar and a
dictionary, and into which he translated the New Testament and other
portions of Scripture. He had already given evidence, in a volume of
sermons dedicated to Maurice, that he was not satisfied with the
traditional views about the Bible. The puzzling questions put to him by
the Zulus strengthened him in this attitude and led him to make a
critical examination of the Pentateuch. His conclusions, positive and
negative, were published in a series of treatises on the Pentateuch,
extending from 1862 to 1879, and, being in advance of his time, were
naturally disputed in England with a fervour of conviction equal to his
own. On the continent they attracted the notice of Abraham Kuenen, and
furthered that scholar's investigations.
While the controversy raged in England, the South African bishops, whose
suspicions Colenso had already incurred by the liberality of his views
respecting polygamy among native converts and by a commentary upon the
Epistle to the Romans (1861), in which he combated the doctrine of
eternal punishment, met in conclave to condemn him, and pronounced his
deposition (December 1863). Colenso, who had refused to appear before
their tribunal otherwise than as sending a protest by proxy, appealed to
the privy council, which pronounced that the metropolitan of Cape Town
(Robert Gray) had no coercive jurisdiction and no authority to interfere
with the bishop of Natal. No decision, therefore, was given upon the
merits of the case. His adversaries, though unable to obtain his
condemnation, succeeded in causing him to be generally inhibited from
preaching in England, and Bishop Gray not only excommunicated him but
consecrated a rival bishop for Natal (W. K. Macrorie), who, however,
took his title from Maritzburg. The contributions of the missionary
societies were withdrawn, but an attempt to deprive him of his episcopal
income was frustrated by a decision of the courts. Colenso, encouraged
by a handsome testimonial raised in England, to which many clergymen
subscribed, returned to his diocese, and devoted the latter years of his
life to further labours as a biblical commentator and translator. He
also championed the cause of the natives against Boer oppression and
official encroachments, a course by which he made more enemies among the
colonists than he had ever made among the clergy. He died at Durban on
the 20th of June 1883. His daughter Frances Ellen Colenso (1840-1887)
published two books on the relations of the Zulus to the British (1880
and 1885), taking a pro-Zulu view; and an elder daughter, Harriette E.
Colenso (b. 1847), became prominent as an advocate of the natives in
opposition to their treatment by Natal, especially in the case of
Dinizulu in 1888-1889 and in 1908-1909.
See his _Life_ by Sir G. W. Cox (2 vols., London, 1888).
COLENSO, a village of Natal on the right or south bank of the Tugela
river, 16 m. by rail south by east of Ladysmith. It was the scene of an
action fought on the 15th of December 1899 between the British forces
under Sir Redvers Buller and the Boers, in which the former were
repulsed. (See LADYSMITH.)
COLEOPTERA, a term used in zoological classification for the true
beetles which form one of the best-marked and most natural of the orders
into which the class Hexapoda (or Insecta) has been divided. For the
relationship of the Coleoptera to other orders of insects see HEXAPODA.
The name (Gr. [Greek: koleos], a sheath, and [Greek: ptera], wings) was
first used by Aristotle, who noticed the firm protective sheaths,
serving as coverings for the hind-wings which alone are used for flight,
without recognizing their correspondence with the fore-wings of other
insects.
These firm fore-wings, or elytra (fig. 1, A), are usually convex above,
with straight hind margins (_dorsa_); when the elytra are closed, the
two hind margins come together along the mid-dorsal line of the body,
forming a _suture_. In many beetles the hind-wings are reduced to mere
vestiges useless for flight, or are altogether absent, and in such cases
the two elytra are often fused together at the suture; thus organs
originally intended for flight have been transformed into an armour-like
covering for the beetle's hind-body. In correlation with their heavy
build and the frequent loss of the power of flight, many beetles are
terrestrial rather than aerial in habit, though a large proportion of
the order can fly well.
Aristotle's term was adopted by Linnaeus (1758), and has been
universally used by zoologists. The identification of the elytra of
beetles with the fore-wings of other insects has indeed been questioned
(1880) by F. Meinert, who endeavoured to compare them with the tegulae
of Hymenoptera, but the older view was securely established by the
demonstration in pupal elytra by J. G. Needham (1898) and W. L. Tower
(1903), of nervures similar to those of the hind-wing, and by the proof
that the small membranous structures present beneath the elytra of
certain beetles, believed by Meinert to represent the whole of the true
fore-wings, are in reality only the alulae.
_Structure._--Besides the conspicuous character of the elytra, beetles
are distinguished by the adaptation of the jaws for biting, the
mandibles (fig. 1, Bb) being powerful, and the first pair of maxillae
(fig. 1, Bc) usually typical in form. The maxillae of the second pair
(fig. 1, Bd) are very intimately fused together to form what is called
the "lower lip" or labium, a firm transverse plate representing the
fused basal portions of the maxillae, which may carry a small median
"ligula," representing apparently the fused inner maxillary lobes, a
pair of paraglossae (outer maxillary lobes), and a pair of palps. The
feelers of beetles differ greatly in the different families (cf. figs.
2b, 9b and 26b, c); the number of segments is usually eleven, but may
vary from two to more than twenty.
The head is extended from behind forwards, so that the crown
(epicranium) is large, while the face (clypeus) is small. The chin
(gula) is a very characteristic sclerite in beetles, absent only in a
few families, such as the weevils. There is usually a distinct labrum
(fig. 1, Ba).
The prothorax is large and "free," i.e. readily movable on the
mesothorax, an arrangement usual among insects with the power of rapid
running. The tergite of the prothorax (pronotum) is prominent in all
beetles, reaching back to the bases of the elytra and forming a
substantial shield for the front part of the body. The tergal regions of
the mesothorax and of the metathorax are hidden under the pronotum and
the elytra when the latter are closed, except that the mesothoracic
scutellum is often visible--a small triangular or semicircular plate
between the bases of the elytra (fig. 1, A). The ventral region of the
thoracic skeleton is complex, each segment usually possessing a median
sternum with paired episterna (in front) and epimera (behind). The
articular surfaces of the haunches (coxae) of the fore-legs are often
conical or globular, so that each limb works in a ball-and-socket joint,
while the hind haunches are large, displacing the ventral sclerites of
the first two abdominal segments (fig. 1, C). The legs themselves (fig.
1, A) are of the usual insectan type, but in many families one, two, or
even three of the five foot-segments may be reduced or absent. In
beetles of aquatic habit the intermediate and hind legs are modified as
swimming-organs (fig. 2, a), while in many beetles that burrow into the
earth or climb about on trees the fore-legs are broadened and
strengthened for digging, or lengthened and modified for clinging to
branches. The hard fore-wings (elytra) are strengthened with marginal
ridges, usually inflected ventrally to form epipleura which fit
accurately along the edges of the abdomen. The upper surface of the
elytron is sharply folded inwards at intervals, so as to give rise to a
regular series of external longitudinal furrows (striae) and to form a
set of supports between the two chitinous layers forming the elytron.
The upper surface often shows a number of impressed dots (punctures).
Along the sutural border of the elytron, the chitinous lamella forms a
tubular space within which are numerous glands. The glands occur in
groups, and lead into common ducts which open in several series along
the suture. Sometimes the glands are found beneath the disk of the
elytron, opening by pores on the surface. The hind-wings, when
developed, are characteristic in form, possessing a sub-costal nervure
with which the reduced radial nervure usually becomes associated. There
are several curved median and cubital nervures and a single anal, but
few cross nervures or areolets. The wing, when not in use, is folded
both lengthwise and transversely, and doubled up beneath the elytron; to
permit the transverse folding, the longitudinal nervures are
interrupted.
[Illustration: FIG. 1.--Structure of Male Stag-Beetle (_Lucanus
cervus_). A, Dorsal view; B, mouth organs; C, under side.]
[Illustration: FIG. 2.--Water Beetles (_Dyticidae_). a, Beetle; b, head
of beetle with feelers and palps; c, larva; d, pupa.]
Ten segments can be recognized--according to the studies of K. W.
Verhoeff (1804-1896)--in a beetle's abdomen, but the tenth sternite is
usually absent. On account of the great extension of the metathorax and
the haunches of the large hind-legs, the first abdominal sternite is
wanting, and the second is usually so much reduced that the foremost
apparent ventral sclerite of the abdomen represents the third sternite.
From this point backwards the successive abdominal segments, as far as
the seventh or eighth, can be readily made out. The ninth and tenth
segments are at most times retracted within the eighth. The female can
protrude a long flexible tube in connexion with the eighth segment,
carrying the sclerites of the ninth at its extremity, and these
sclerites may carry short hairy processes--the stylets. This flexible
tube is the functional ovipositor, the typical insectan ovipositor with
its three pairs of processes (see HEXAPODA) being undeveloped among the
Coleoptera. In male beetles, however, the two pairs of genital processes
(paramera) belonging to the ninth abdominal segment are always present,
though sometimes reduced. Between them is situated, sometimes
asymmetrically, the prominent intromittent organ.
In the structure of the digestive system, beetles resemble most other
mandibulate insects, the food-canal consisting of gullet, crop, gizzard,
mid-gut or stomach, intestine and rectum. The stomach is beset
throughout its length with numerous small, finger-like caecal tubes. The
excretory (malpighian) tubes are few in number, either four or six. Many
beetles have, in connexion with the anus, glands which secrete a
repellent acid fluid, serving as a defence for the insect when attacked.
The "bombardier" ground beetles (fig. 5) have this habit. Oil-beetles
(figs. 23 and 24) and ladybirds (fig. 32) defend themselves by ejecting
drops of fluid from the knee-joints. The nervous system is remarkably
concentrated in some beetles, the abdominal ganglia showing a tendency
to become shifted forward and crowded together, and in certain chafers
all the thoracic and abdominal ganglia are fused into a single
nerve-centre situated in the thorax,--a degree of specialization only
matched in the insectan class among the Hemiptera and some muscid flies.
_Development._--The embryonic development (see HEXAPODA) has been
carefully studied in several genera of beetles. As regards growth
after hatching, all beetles undergo a "complete" metamorphosis, the
wing-rudiments developing beneath the cuticle throughout the larval
stages, and a resting pupal stage intervening between the last larval
instar[1] and the imago. The coleopterous pupa (figs. 2d, 3c) is
always "free," the legs, wings and other appendages not being fixed
to the body as in the pupa of a moth, and the likeness of pupa to
perfect insect is very close.
The most striking feature in the development of beetles is the great
diversity noticeable in the outward form of the larva in different
families. The larva of a ground-beetle or a carnivorous water-beetle
(fig. 2 c) is an active elongate grub with well-armoured cuticle. The
head--carrying feelers, mandibles and two pairs of maxillae--is
succeeded by the three thoracic segments, each bearing a pair of
strong five-segmented legs, whose feet, like those of the adult, carry
two claws. Ten segments can be distinguished in the tapering abdomen,
the ninth frequently bearing a pair of tail-feelers (cerci), and the
tenth, attached ventrally to the ninth, having the anal opening at its
extremity and performing the function of a posterior limb, supporting
and temporarily fixing the tail end of the insect on the surface over
which it crawls. Such a typically "campodeiform" grub, moving actively
about in pursuit of prey, is the one extreme of larval structure to be
noticed among the Coleoptera. The other is exemplified by the white,
wrinkled, soft-skinned, legless grub of a weevil, which lives
underground feeding on roots, or burrows in the tissues of plants
(fig. 3 b). Between these two extremes we find various transitional
forms: an active larva, as described above, but with four-segmented,
single-clawed legs, as among the rove-beetles and their allies; the
body well armoured, but slender and worm-like, with very short legs as
in wireworms and mealworms (figs. 18, 21 b); the body shortened, with
the abdomen swollen, but protected with tubercles and spines, and with
longish legs adapted for an active life, as in the predaceous larvae
of ladybirds; the body soft-skinned, swollen and caterpillar-like,
with legs well developed, but leading a sluggish underground life, as
in the grub of a chafer; the body soft-skinned and whitish, and the
legs greatly reduced in size, as in the wood-feeding grub of a
longhorn beetle. In the case of certain beetles whose larvae do not
find themselves amid appropriate food from the moment of hatching, but
have to migrate in search of it, an early larval stage, with legs, is
followed by later sluggish stages in which legs have disappeared,
furnishing examples of what is called hypermetamorphosis. For example,
the grub of a pea or bean beetle (_Bruchus_) is hatched, from the egg
laid by its mother on the carpel of a leguminous flower, with three
pairs of legs and spiny processes on the prothorax. It bores through
and enters the developing seed, where it undergoes a moult and becomes
legless. Similarly the newly-hatched larva of an oil-beetle (_Meloe_)
is an active little campodeiform insect, which, hatched from an egg
laid among plants, waits to attach itself to a passing bee. Carried to
the bee's nest, it undergoes a moult, and becomes a fat-bodied grub,
ready to lead a quiet life feeding on the bee's rich food-stores.
[Illustration: From Chittenden, _Yearbook_, 1894, U.S. Dept. of
Agriculture.
FIG. 3.--Grain Weevils. a, _Calandra granaria_; b, larva; c, pupa; d,
_C. oryzae_.]
_Distribution and Habits._--The Coleoptera are almost world-wide in
their distribution, being represented in the Arctic regions and on
almost all oceanic islands. Most of the dominant families--such as the
_Carabidae_ (ground-beetles), _Scarabaeidae_ (chafers), or
_Curculionidae_ (weevils) have a distribution as wide as the order. But
while some large families, such as the _Staphylinidae_ (rove-beetles)
are especially abundant on the great northern continents, becoming
scarcer in the tropics, others, the _Cicindelidae_ (tiger-beetles), for
example, are most strongly represented in the warmer regions of the
earth, and become scarce as the collector journeys far to south or
north. The distribution of many groups of beetles is restricted in
correspondence with their habits; the _Cerambycidae_ (longhorns), whose
larvae are wood-borers, are absent from timberless regions, and most
abundant in the great tropical forests. Some families are very
restricted in their range. The _Amphizoidae_, for example, a small
family of aquatic beetles, are known only from western North America and
Eastern Tibet, while an allied family, the _Pelobiidae_, inhabit the
British Isles, the Mediterranean region, Tibet and Australia. The
beetles of the British islands afford some very interesting examples of
restricted distribution among species. For example, large and
conspicuous European beetles, such as the stag-beetle (fig. 1, _Lucanus
cervus_) and the great water-beetle (_Hydrophilus piceus_, fig. 20), are
confined to eastern and southern Britain, and are unknown in Ireland. On
the other hand, there are Arctic species like the ground-beetle,
_Pelophila borealis_, and south-western species like the boring weevil,
_Mesites Tardyi_, common in Ireland, and represented in northern or
western Britain, but unknown in eastern Britain or in Central Europe.
Careful study of insular faunas, such as that of Madeira by T. V.
Wollaston, and of the Sandwich Islands by D. Sharp, and the comparison
of the species found with those of the nearest continental land, furnish
the student of geographical distribution with many valuable and
suggestive facts.
Notes on habit are given below in the accounts of the various families.
In general it may be stated that beetles live and feed in almost all the
diverse ways possible for insects. There are carnivores, herbivores and
scavengers among them. Various species among those that are predaceous
attack smaller insects, hunt in packs crustaceans larger than
themselves, insert their narrow heads into snail-shells to pick out and
devour the occupants, or pursue slugs and earthworms underground. The
vegetable-feeders attack leaves, herbaceous or woody stems and roots;
frequently different parts of a plant are attacked in the two active
stages of the life-history; the cockchafers, for example, eating leaves,
and their grubs gnawing roots. Some of the scavengers, like the burying
beetles, inter the bodies of small vertebrates to supply food for
themselves and their larvae, or, like the "sacred" beetle of Egypt,
collect for the same purpose stores of dung. Many beetles of different
families have become the "unbidden guests" of civilized man, and may be
found in dwelling-houses, stores and ships' cargoes, eating food-stuffs,
paper, furniture, tobacco and drugs. Hence we find that beetles of some
kind can hold their own anywhere on the earth's surface. Some climb
trees and feed on leaves, while others tunnel between bark and wood.
Some fly through the air, others burrow in the earth, while several
families have become fully adapted to life in fresh water. A large
number of beetles inhabit the deep limestone caves of Europe and North
America, while many genera and some whole families are at home nowhere
but in ants' nests. Most remarkable is the presence of a number of
beetles along the seashore between tide-marks, where, sheltered in some
secure nook, they undergo immersion twice daily, and have their active
life confined to the few hours of the low ebb.
_Stridulating Organs._--Many beetles make a hissing or chirping sound by
rubbing a "scraper," formed by a sharp edge or prominence on some part
of their exoskeleton, over a "file" formed by a number of fine ridges
situate on an adjacent region. These stridulating organs were mentioned
by C. Darwin as probable examples of the action of sexual selection;
they are, however, frequently present in both sexes, and in some
families also in the larvae. An account of the principal types of
stridulators that have been described has been published by C. J. Gahan
(1900). The file may be on the head--either upper or lower surface--and
the scraper formed by the front edge of the prothorax, as in various
wood-boring beetles (_Anobium_ and _Scolytus_). Or ridged areas on the
sides of the prothorax may be scraped by "files" on the front thighs, as
in some ground-beetles. Among the longhorn beetles, the prothorax
scrapes over a median file on the mid-dorsal aspect of the mesothorax.
In a large number of beetles of different families, stridulating areas
occur on various segments of the abdomen, and are scraped by the elytra.
It is remarkable that these organs are found in similar positions in
genera belonging to widely divergent families, while two genera of the
same family may have them in different positions. It follows, therefore,
that they have been independently acquired in the course of the
evolution of the Coleoptera.
Stridulating organs among beetle-larvae have been noted, especially in
the wood-feeding grub of the stag-beetles (_Lucanidae_) and their allies
the _Passalidae_, and in the dung-eating grubs of the dor-beetles
(_Geotrupes_), which belong to the chafer family (_Scarabaeidae_). These
organs are described by J. C. Schiodte and D. Sharp; in the stag-beetle
larva a series of short tubercles on the hind-leg is drawn across the
serrate edge of a plate on the haunch of the intermediate legs, while in
the Passalid grub the modified tip of the hind-leg acts as a scraper,
being so shortened that it is useless for locomotion, but highly
specialized for producing sound. Whatever may be the true explanation of
stridulating organs in adult beetles, sexual selection can have had
nothing to do with the presence of these highly-developed larval
structures. It has been suggested that the power of stridulation would
be advantageous to wood-boring grubs, the sound warning each of the
position of its neighbour, so that adjacent burrowers may not get in
each other's way. The root-feeding larvae of the cockchafer and allied
members of the _Scarabaeidae_ have a ridged area on the mandible, which
is scraped by teeth on the maxillae, apparently forming a stridulating
organ.
_Luminous Organs._--The function of the stridulating organs just
described is presumably to afford means of recognition by sound. Some
beetles emit a bright light from a portion of their bodies, which leads
to the recognition of mate or comrade by sight. In the wingless female
glow-worm (_Lampyris_, fig. 15 f) the luminous region is at the hinder
end, the organ emitting the light consisting, according to H. von
Wielowiejski (1882), of cells similar to those of the fat-body,
containing a substance that undergoes oxidation. The illumination is
intermittent, and appears to be under the control of the insect's
nervous system. The well-known "fire-flies" of the tropics are large
click-beetles (_Elateridae_), that emit light from paired spots on the
prothorax and from the base of the ventral abdominal region. The
luminous organs of these beetles consist of a specialized part of the
fat-body, with an inner opaque and an outer transparent layer. Its
structure has been described by C. Heinemann, and its physiology by R.
Dubois (1886), who considers that the luminosity is due to the influence
of an enzyme in the cells of the organ upon a special substance in the
blood. The eggs and larvae of the fire-flies are luminous as well as the
perfect beetles.
_Fossil History._--The Coleoptera can be traced back farther in time
than any other order of insects with complete transformations, if the
structures that have been described from the Carboniferous rocks of
Germany are really elytra. In the Triassic rocks of Switzerland remains
of weevils (_Curculionidae_) occur, a family which is considered by many
students the most specialized of the order. And when we know that the
_Chrysomelidae_ and _Buprestidae_ also lived in Triassic, and the
_Carabidae_, _Elateridae_, _Cerambycidae_ and _Scarabaeidae_, in Liassic
times, we cannot doubt that the great majority of our existing families
had already been differentiated at the beginning of the Mesozoic epoch.
Coming to the Tertiary we find the Oligocene beds of Aix, of east
Prussia (amber) and of Colorado, and the Miocene of Bavaria, especially
rich in remains of beetles, most of which can be referred to existing
genera.
_Classification._--The Coleoptera have been probably more assiduously
studied by systematic naturalists than any other order of insects. The
number of described species can now hardly be less than 100,000, but
there is little agreement as to the main principles of a natural
classification. About eighty-five families are generally recognized; the
difficulty that confronts the zoologists is the arrangement of these
families in "superfamilies" or "sub-orders." Such obvious features as
the number of segments in the foot and the shape of the feeler were
used by the early entomologists for distinguishing the great groups of
beetles. The arrangement dependent on the number of tarsal segments--the
order being divided into tribes _Pentamera_, _Tetramera_, _Heteromera_
and _Trimera_--was suggested by E. L. Geoffroy in 1762, adopted by P. A.
Latreille, and used largely through the 19th century. W. S. Macleay's
classification (1825), which rested principally on the characters of the
larvae, is almost forgotten nowadays, but it is certain that in any
systematic arrangement which claims to be natural the early stages in
the life-history must receive due attention. In recent years
classifications in part agreeing with the older schemes but largely
original, in accord with researches on the comparative anatomy of the
insects, have been put forward. Among the more conservative of these may
be mentioned that of D. Sharp (1899), who divides the order into six
great series of families: _Lamellicornia_ (including the chafers and
stag-beetles and their allies with five-segmented feet and plate-like
terminal segments to the feelers); _Adephaga_ (carnivorous, terrestrial
and aquatic beetles, all with five foot-segments); _Polymorpha_
(including a heterogeneous assembly of families that cannot be fitted
into any of the other groups); _Heteromera_ (beetles with the fore and
intermediate feet five-segmented, and the hind-feet four-segmented);
_Phytophaga_ (including the leaf-beetles, and longhorns, distinguished
by the apparently four-segmented feet), and _Rhynchophora_ (the weevils
and their allies, with head prolonged into a snout, and feet with four
segments). L. Ganglbauer (1892) divides the whole order into two
sub-orders only, the _Caraboidea_ (the _Adephaga_ of Sharp and the older
writers) and the _Cantharidoidea_ (including all other beetles), since
the larvae of _Caraboidea_ have five-segmented, two-clawed legs, while
those of all other beetles have legs with four segments and a single
claw. A. Lameere (1900) has suggested three sub-orders, the
_Cantharidiformia_ (including the _Phytophaga_, the _Heteromera_, the
_Rhynchophora_ and most of the _Polymorpha_ of Sharp's classification),
the _Staphyliniformia_ (including the rove-beetles, carrion-beetles and
a few allied families of Sharp's _Polymorpha_), and the _Carabidiformia_
(_Adephaga_). Lameere's classification is founded on the number of
abdominal sterna, the nervuration of the wings, the number of malpighian
tubules (whether four or six) and other structural characters.
Preferable to Lameere's system, because founded on a wider range of
adult characters and taking the larval stages into account, is that of
H. J. Kolbe (1901), who recognizes three sub-orders: (i.) the
_Adephaga_; (ii.) the _Heterophaga_, including the _Staphylinoidea_, the
_Actinorhabda_ (_Lamellicornia_), the _Heterorhabda_ (most of Sharp's
_Polymorpha_), and the _Anchistopoda_ (the _Phytophaga_, with the
ladybirds and some allied families which Sharp places among the
_Polymorpha_); (iii.) the _Rhynchophora_.
Students of the Coleoptera have failed to agree not only on a system of
classification, but on the relative specialization of some of the groups
which they all recognize as natural. Lameere, for example, considers
some of his _Cantharidiformia_ as the most primitive Coleoptera. J. L.
Leconte and G. H. Horn placed the _Rhynchophora_ (weevils) in a group
distinct from all other beetles, on account of their supposed primitive
nature. Kolbe, on the other hand, insists that the weevils are the most
modified of all beetles, being highly specialized as regards their adult
structure, and developing from legless maggots exceedingly different
from the adult; he regards the Adephaga, with their active armoured
larvae with two foot-claws, as the most primitive group of beetles, and
there can be little doubt that the likeness between larvae and adult may
safely be accepted as a primitive character among insects. In the
Coleoptera we have to do with an ancient yet dominant order, in which
there is hardly a family that does not show specialization in some point
of structure or life-history. Hence it is impossible to form a
satisfactory linear series.
In the classification adopted in this article, the attempt has been made
to combine the best points in old and recent schemes, and to avoid the
inconvenience of a large heterogeneous group including the vast majority
of the families.
ADEPHAGA.--This tribe includes beetles of carnivorous habit with five
segments on every foot, simple thread-like feelers with none of the
segments enlarged to form club or pectination, and the outer lobs
(galea) of the first maxilla usually two-segmented and palpiform (fig.
4 b). The transverse fold of the hind-wing is towards the tip, about
two-thirds of the wing-length from the base. At this fold the median
nervure stops and is joined by a cross nervure to the radial, which
can be distinguished throughout its length from the subcostal. There
are four malpighian tubules. In the ovarian tubes of Adephaga small
yolk-chambers alternate with the egg-chambers, while in all other
beetles there is only a single large yolk-chamber at the narrow end of
the tube. The larvae (fig. 2 c) are active, with well-chitinized
cuticle, often with elongate tail-feelers (cerci), and with
five-segmented legs, the foot-segment carrying two claws.
[Illustration: FIG. 4.--_Mormolyce phyllodes_. Java. a, Labium; b,
maxilla; c, labrum; d, mandible.]
The generalized arrangement of the wing-nervure and the nature of the
larva, which is less unlike the adult than in other beetles,
distinguish this tribe as primitive, although the perfect insects are,
in the more dominant families, distinctly specialized. Two very small
families of aquatic beetles seem to stand at the base of the series,
the _Amphizoidae_, whose larvae are broad and well armoured with short
cerci, and the _Pelobiidae_, which have elongate larvae, tapering to
the tail end, where are long paired cerci and a median process,
recalling the grub of a Mayfly.
[Illustration: FIG. 5.--_Pheropsophus Jurinei_. W. Africa.]
[Illustration: FIG. 6.--_Carabus rutilans_. Spain.]
The _Dyticidae_ (fig. 2) are Adephaga highly specialized for life in
the water, the hind-legs having the segments short, broad and fringed,
so as to be well adapted for swimming, and the feet without claws. The
metasternum is without the transverse linear impression that is found
in most families of Adephaga. The beetles are ovoid in shape, with
smooth contours, and the elytra fit over the edges of the abdomen so
as to enclose a supply of air, available for use when the insect
remains under water. The fore-legs of many male dyticids have the
three proximal foot-segments broad and saucer-shaped, and covered
with suckers, by means of which they secure a firm hold of their
mates. Larval dyticids (fig. 2 b) possess slender, curved, hollow
mandibles, which are perforated at the tip and at the base, being thus
adapted for sucking the juices of victims. Large dyticid larvae often
attack small fishes and tadpoles. They breathe by piercing the surface
film with the tail, where a pair of spiracles are situated. The pupal
stage is passed in an earthen cell, just beneath the surface of the
ground. Nearly 2000 species of _Dyticidae_ are known: they are
universally distributed, but are most abundant in cool countries. The
_Haliplidae_ form a small aquatic family allied to the _Dyticidae_.
[Illustration: FIG. 7.--_Cicindela sylvatica_ (Wood Tiger-Beetle).
Europe.]
[Illustration: FIG. 8.--_Manticora tuberculata_. S. Africa.]
The _Carabidae_, or ground-beetles, comprising 13,000 species, form
the largest and most typical family of the Adephaga (figs. 4, 5, 6),
the legs of all three pairs being alike and adapted for rapid running.
In many _Carabidae_ the hind-wings are reduced or absent, and the
elytra fused together along the suture. Many of our native species
spend the day lurking beneath stones, and sally forth at night in
pursuit of their prey, which consists of small insects, earthworms and
snails. But a number of the more brightly coloured ground-beetles run
actively in the sunshine. The carabid larva is an active well-armoured
grub with the legs and cerci variable in length. Great differences in
the general form of the body may be observed in the family. For
example, the stout, heavy body of _Carabus_ (fig. 6) contrasts
markedly with the wonderful flattened abdomen and elytra of
_Mormolyce_ (fig. 4), a Malayan genus found beneath fallen trees, a
situation for which its compressed shape is admirably adapted. Blind
_Carabidae_ form a large proportion of cave-dwelling beetles, and
several species of great interest live between tide-marks along the
seashore.
The _Cicindelidae_, or tiger-beetles (figs. 7, 8) are the most highly
organized of all the Adephaga. The inner lobe (lacinia) of the first
maxilla terminates in an articulated hook, while in the second
maxillae (labium) both inner and outer lobes ("ligula" and
"para-glossae") are much reduced. The face (clypeus) is broad,
extending on either side in front of the insertion of the feelers. The
beetles are elegant insects with long, slender legs, running quickly,
and flying in the sunshine. The pronotum and elytra are often adorned
with bright colours or metallic lustre, and marked with stripes or
spots. The beetles are fierce in nature and predaceous in habit, their
sharp toothed mandibles being well adapted for the capture of small
insect-victims. The larvae are more specialized than those of other
Adephaga, the head and prothorax being very large and broad, the
succeeding segments slender and incompletely chitinized. The fifth
abdominal segment has a pair of strong dorsal hook-like processes, by
means of which the larva supports itself in the burrow which it
excavates in the earth, the great head blocking the entrance with the
mandibles ready to seize on any unwary insect that may venture within
reach.
[Illustration: FIG. 9.
a _Gyrinus sulcatus_ (Grooved Whirligig). Europe.
b Antenna of _Gyrinus_.
c Larva of _Gyrinus_.]
Two or three families may be regarded as aberrant Adephaga. The
_Paussidae_ are a very remarkable family of small beetles, mostly
tropical, found only in ants' nests, or flying by night, and
apparently migrating from one nest to another. The number of antennal
segments varies from eleven to two. It is supposed that these beetles
secrete a sweet substance on which the ants feed, but they have been
seen to devour the ants' eggs and grubs. The _Gyrinidae_, or whirligig
beetles (fig. 9), are a curious aquatic family with the feelers (fig.
9, b) short and reduced as in most _Paussidae_. They are flattened
oval in form, circling with gliding motion over the surface film of
the water, and occasionally diving, when they carry down with them a
bubble of air. The fore-legs are elongate and adapted for clasping,
while the short and flattened intermediate and hind legs form very
perfect oar-like propellers. The larva of _Gyrinus_ (fig. 9, c) is
slender with elongate legs, and the abdominal segments carry paired
tracheal gills.
STAPHYLINOIDEA.--The members of this tribe may be easily recognized by
their wing-nervuration. Close to a transverse fold near the base of
the wing, the median nervure divides into branches which extend to the
wing-margin; there is a second transverse fold near the tip of the
wing, and cross nervures are altogether wanting. There are four
malpighian tubes, and all five tarsal segments are usually
recognizable. With very few exceptions, the larva in this group is
active and campodeiform, with cerci and elongate legs as in the
Adephaga, but the leg has only four segments and one claw.
[Illustration: FIG. 10.--_Silpha quadripunctata_. Europe.]
[Illustration: FIG. 11.--_Necrophorus vespillo_ (Sexton Beetle).
Europe.]
The _Silphidae_, or carrion beetles, form one of the best-known
families of this group. They are rotund or elongate insects with
conical front haunches, the elytra generally covering (fig. 10) the
whole dorsal region of the abdomen, but sometimes leaving as many as
four terga exposed (fig. 11). Some of these beetles are brightly
coloured, while others are dull black. They are usually found in
carrion, and the species of _Necrophorus_ (fig. 11) and _Necrophaga_
are valuable scavengers from their habit of burying small vertebrate
carcases which may serve as food for their larvae. At this work a
number of individuals are associated together. The larvae that live
underground have spiny dorsal plates, while those of the _Silpha_
(fig. 10) and other genera that go openly about in search of food
resemble wood-lice. About 1000 species of _Silphidae_ are known.
Allied to the _Silphidae_ are a number of small and obscure families,
for which reference must be made to monographs of the order. Of
special interest among these are the _Histeridae_, compact beetles
(fig. 12) with very hard cuticle and somewhat abbreviated elytra, with
over 2000 species, most of which live on decaying matter, and the
curious little _Pselaphidae_, with three-segmented tarsi, elongate
palpi, and shortened abdomen; the latter are usually found in ants'
nests, where they are tended by the ants, which take a sweet fluid
secreted among little tufts of hair on the beetles' bodies; these
beetles, which are carried about by the ants, sometimes devour their
larvae. The _Trichopterygidae_, with their delicate narrow fringed
wings, are the smallest of all beetles, while the _Platypsyllidae_
consist of only a single species of curious form found on the beaver.
[Illustration: FIG. 12. _Hister iv-maculatus_ (Mimic Beetle). Europe.]
[Illustration: FIG. 13. _Oxyporus rufus_. Europe.]
[Illustration: FIG. 14. _Stenus biguttatus_. Europe.]
The _Staphylinidae_, or rove-beetles--a large family of nearly 10,000
species--may be known by their very short elytra, which cover only two
of the abdominal segments, leaving the elongate hind-body with seven
or eight exposed, firm terga (figs. 13, 14). These segments are very
mobile, and as the rove-beetles run along they often curl the abdomen
upwards and forwards like the tail of a scorpion. The _Staphylinid_
larvae are typically campodeiform. Beetles and larvae are frequently
carnivorous in habit, hunting for small insects under stones, or
pursuing the soft-skinned grubs of beetles and flies that bore in
woody stems or succulent roots. Many _Staphylinidae_ are constant
inmates of ants' nests.
MALACODERMATA.--In this tribe may be included a number of families
distinguished by the softness of the cuticle, the presence of seven or
eight abdominal sterna and of four malpighian tubes, and the firm,
well-armoured larva (fig. 15, c) which is often predaceous in habit.
The mesothoracic epimera bound the coxal cavities of the intermediate
legs. The _Lymexylonidae_, a small family of this group, characterized
by its slender, undifferentiated feelers and feet, is believed by
Lameere to comprise the most primitive of all living beetles, and
Sharp lays stress on the undeveloped structure of the tribe generally.
[Illustration: FIG. 15.--Glow-worm. _Lampyris noctiluca_. a, Male; b,
female; c, larva (ventral view). Europe.]
The _Lampyridae_ are a large family, of which the glow-worm
(_Lampyris_) and the "soldier beetles" (_Telephorus_) are familiar
examples. The female "glow-worm" (fig. 15, b), emitting the well-known
light (see above), is wingless and like a larva; the luminosity seems
to be an attraction to the male, whose eyes are often exceptionally
well developed. Some male members of the family have remarkably
complex feelers. In many genera of _Lampyridae_ the female can fly as
well as the male; among these are the South European "fireflies."
TRICHODERMATA.--Several families of rather soft-skinned beetles, such
as the _Melyridae_, _Cleridae_ (fig. 16), _Corynetidae_, _Dermestidae_
(fig. 17), and _Dascillidae_, are included in this tribe. They may be
distinguished from the Malacodermata by the presence of only five or
six abdominal sterna, while six malpighian tubes are present in some
of the families. The beetles are hairy and their larvae well-armoured
and often predaceous. Several species of _Dermestidae_ are commonly
found in houses, feeding on cheeses, dried meat, skins and other such
substances. The "bacon beetle" (_Dermestes lardarius_), and its hard
hairy larva, are well known. According to Sharp, all Dermestid larvae
probably feed on dried animal matters; he mentions one species that
can find sufficient food in the horsehair of furniture, and another
that eats the dried insect-skins hanging in old cobwebs.
[Illustration: FIG. 16.--_Clerus apiarus_ (Hive Beetle). Europe.]
[Illustration: FIG. 17.--_Dermestes lardarius_ (Bacon Beetle).]
STERNOXIA.--This is an important tribe of beetles, including families
with four malpighian tubes and only five or six abdominal sterna,
while in the thorax there is a backwardly directed process of the
prosternum that fits into a mesosternal cavity. The larvae are
elongate and worm-like, with short legs but often with hard strong
cuticle.
[Illustration: FIG. 18.--A, Wireworm; B, pupa of Click Beetle; C,
adult Click Beetle (_Agriotes lineatum_).]
The _Elateridae_ or click beetles (fig. 18) have the prosternal
process just mentioned, capable of movement in and out of the
mesosternal cavity, the beetles being thus enabled to leap into the
air, hence their popular name of "click-beetles" or "skip-jacks." The
prothorax is convex in front, and is usually drawn out behind into a
prominent process on either side, while the elytra are elongate and
tapering. Many of the tropical American _Elateridae_ emit light from
the spots on the prothorax and an area beneath the base of the
abdomen; these are "fireflies" (see above). The larvae of _Elateridae_
are elongate, worm-like grubs, with narrow bodies, very firm cuticle,
short legs, and a distinct anal proleg. They are admirably adapted for
moving through the soil, where some of them live on decaying organic
matter, while others are predaceous. Several of the elaterid larvae,
however, gnaw roots and are highly destructive to farm crops. These
are the well-known "wire-worms" (q.v.).
[Illustration: FIG. 19.--_Catoxantha bicolor_. Java.]
The _Buprestidae_ are distinguished from the _Elateridae_ by the
immobility of the prosternal process in the mesosternal cavity and by
the absence of the lateral processes at the hind corners of the
prothorax. Many tropical _Buprestidae_ are of large size (fig. 19),
and exhibit magnificent metallic colours; their elytra are used as
ornaments in human dress. The larvae are remarkable for their small
head, very broad thorax, with reduced legs, and narrow elongate
abdomen. They feed by burrowing in the roots and stems of plants.
BOSTRYCHOIDEA.--This tribe is distinguished from the Malacoderma and
allied groups by the mesothoracic epimera not bounding the coxal
cavities of the intermediate legs. The downwardly directed head is
covered by the pronotum, and the three terminal antennal segments form
a distinct club. To this group belong the _Bostrychidae_ and
_Ptinidae_, well known (especially the latter family) for their
ravages in old timber. The larvae are stout and soft-skinned, with
short legs in correlation with their burrowing habit. The noises made
by some _Ptinidae_ (_Anobium_) tapping on the walls of their burrows
with their mandibles give rise to the "death tick" that has for long
alarmed the superstitious.
[Illustration: FIG. 20.--_Hydrophilus piceus_ (Black Water Beetle).
Europe.]
CLAVICORNIA.--This is a somewhat heterogeneous group, most of whose
members are characterized by clubbed feelers and simple, unbroadened
tarsal segments--usually five on each foot--but in some families and
genera the males have less than the normal number on the feet of one
pair. There are either four or six malpighian tubes. A large number of
families, distinguished from each other by more or less trivial
characters, are included here, and there is considerable diversity in
the form of the larvae. The best-known family is the _Hydrophilidae_,
in which the feelers are short with less than eleven segments and the
maxillary palpi very long. Some members of this family--the large
black _Hydrophilus piceus_ (fig. 20), for example--are specialized for
an aquatic life, the body being convex and smooth as in the
_Dyticidae_, and the intermediate and hind-legs fringed for swimming.
When _Hydrophilus_ dives it carries a supply of air between the elytra
and the dorsal surface of the abdomen, while air is also entangled in
the pubescence which extends beneath the abdomen on either side, being
scooped in bubbles by the terminal segments of the feelers when the
insect rises to the surface. Many of the _Hydrophilidae_ construct,
for the protection of their eggs, a cocoon formed of a silky material
derived from glands opening at the tip of the abdomen. That of
_Hydrophilus_ is attached to a floating leaf, and is provided with a
hollow, tapering process, which projects above the surface and
presumably conveys air to the enclosed eggs. Other _Hydrophilidae_
carry their egg-cocoons about with them beneath the abdomen. Many
_Hydrophilidae_, unmodified for aquatic life, inhabit marshes. The
larvae in this family are well-armoured, active and predaceous. Of the
numerous other families of the Clavicornia may be mentioned the
_Cucujidae_ and _Cryptophagidae_, small beetles, examples of which may
be found feeding on stored seeds or vegetable refuse, and the
_Mycetophagidae_, which devour fungi. The _Nitidulidae_ are a large
family with 1600 species, among which members of the genus
_Meligethes_ are often found in numbers feeding on blossoms, while
others live under the bark of trees and prey on the grubs of boring
beetles.
HETEROMERA.--This tribe is distinguished by the presence of the normal
five segments in the feet of the fore and intermediate legs, while
only four segments are visible in the hind-foot. Considerable
diversity is to be noticed in details of structure within this group,
and for an enumeration of all the various families which have been
proposed and their distinguishing characters the reader is referred to
one of the monographs mentioned below. Some of the best-known members
of the group belong to the _Tenebrionidae_, a large family containing
over 10,000 species and distributed all over the world. The
tenebrionid larva is elongate, with well-chitinized cuticle, short
legs and two stumpy tail processes, the common mealworm (fig. 21)
being a familiar example. Several species of this family are found
habitually in stores of flour or grain. The beetles have feelers with
eleven segments, whereof the terminal few are thickened so as to form
a club. The true "black-beetles" or "churchyard beetles" (_Blaps_)
(fig. 22) belong to this family; like members of several allied genera
they are sooty in colour, and somewhat resemble ground beetles
(_Carabi_) in general appearance.
[Illustration: FIG. 21.--(a) _Tenebrio molitor_ (Flour Beetle).
Europe. (b) Larva, or mealworm.]
[Illustration: FIG. 22.--_Blaps mortisaga_ (Churchyard Beetle).
Europe.]
[Illustration: FIG. 23.--_Meloe proscarabaeus_ (Oil Beetle). Europe.]
[Illustration: FIG. 24.--_Lytta vesicatoria_ (Blister Beetle).
Europe.]
The most interesting of the Heteromera, and perhaps of all the
Coleoptera, are some beetles which pass through two or more larval
forms in the course of the life-history (hypermetamorphosis). These
belong to the families _Rhipidophoridae_ and _Meloidae_. The latter
are the oil beetles (fig. 23) or blister beetles (fig. 24), insects
with rather soft cuticle, the elytra (often abbreviated) not fitting
closely to the sides of the abdomen, the head constricted behind the
eyes to form a neck, and the claws of the feet divided to the base.
Several of the _Meloidae_ (such as the "Spanish fly," fig. 24) are of
economic importance, as they contain a vesicant substance used for
raising medicinal blisters on the human skin. The wonderful
transformations of these insects were first investigated by G. Newport
in 1851, and have recently been more fully studied by C. V. Riley
(1878) and J. H. Fabre. The first larval stage is the "triungulin," a
tiny, active, armoured larva with long legs (each foot with three
claws) and cercopods. In the European species of _Sitaris_ and _Meloe_
these little larvae have the instinct of clinging to any hairy object.
All that do not happen to attach themselves to a bee of the genus
_Anthophora_ perish, but those that succeed in reaching the right host
are carried to the nest, and as the bee lays an egg in the cell the
triungulin slips off her body on to the egg, which floats on the
surface of the honey. After eating the contents of the egg, the larva
moults and becomes a fleshy grub with short legs and with paired
spiracles close to the dorsal region, so that, as it floats in and
devours the honey, it obtains a supply of air. After a resting
(pseudo-pupal) stage and another larval stage, the pupa is developed.
In the American EPICAUTA VITTATA the larva is parasitic on the eggs
and egg-cases of a locust. The triungulin searches for the eggs, and,
after a moult, becomes changed into a soft-skinned tapering larva.
This is followed by a resting (pseudo-pupal) stage, and this by two
successive larval stages like the grub of a chafer. The
RHIPIDOPHORIDAE are beetles with, short elytra, the feelers pectinate
in the males and serrate in the females. The life-history of
_Metoecus_ has been studied by T. A. Chapman, who finds that the eggs
are laid in old wood, and that the triungulin seeks to attach itself
to a social wasp, who carries it to her nest. There it feeds first as
an internal parasite of the wasp-grub, then bores its way out, moults
and devours the wasp larva from outside. The wasps are said to leave
the larval or pupal _Metoecus_ unmolested, but they are hostile to the
developed beetles, which hasten to leave the nest as soon as possible.
STREPSIPTERA.--Much difference of opinion has prevailed with regard to
the curious, tiny, parasitic insects included in this division, some
authorities considering that they should be referred to a distinct
order, while others would group them in the family _Meloidae_ just
described. While from the nature of their life-history there is no
doubt that they have a rather close relationship to the _Meloidae_,
their structure is so remarkable that it seems advisable to regard
them as at least a distinct tribe of Coleoptera.
They may be comprised in a single family, the _Stylopidae_. The males
are very small, free-flying insects with the prothorax, mesothorax and
elytra greatly reduced, the latter appearing as little, twisted
strips, while the metathorax is relatively large, with its wings broad
and capable of longitudinal folding. The feelers are branched and the
jaws vestigial. The female is a segmented, worm-like creature,
spending her whole life within the body of the bee, wasp or bug on
which she is parasitic. One end of her body protrudes from between two
of the abdominal segments of the host; it has been a subject of
dispute whether this protruded end is the head or the tail, but there
can be little doubt that it is the latter. While thus carried about by
the host-insect, the female is fertilized by the free-flying male, and
gives birth to a number of tiny triungulin larvae. The chief points in
the life-history of _Stylops_ and _Xenos_, which are parasitic on
certain bees (_Andrena_) and wasps (_Polistes_), have been
investigated by K. T. E. von Siebold (1843) and N. Nassonov (1892).
The little triungulins escape on to the body of the bee or wasp; then
those that are to survive must leave their host for a non-parasitized
insect. Clinging to her hairs they are carried to the nest, where they
bore into the body of a bee or wasp larva, and after a moult become
soft-skinned legless maggots. The growth of the parasitic larva does
not stop the development of the host-larva, and when the latter
pupates and assumes the winged form, the stylopid, which has completed
its transformation, is carried to the outer world. The presence of a
_Stylops_ causes derangement in the body of its host, and can be
recognized by various external signs. Other genera of the family are
parasitic on Hemiptera--bugs and frog-hoppers--but nothing is known as
to the details of their life-history.
LAMELLICORNIA.--This is a very well-marked tribe of beetles,
characterized by the peculiar elongation and flattening of three or
more of the terminal antennal segments, so that the feeler seems to
end in a number of leaf-like plates, or small comb-teeth (fig. 26, b,
c). The wings are well developed for flight, and there is a tendency
in the group, especially among the males, towards an excessive
development of the mandibles or the presence of enormous, horn-like
processes on the head or pronotum. There are four malpighian tubes.
The larvae are furnished with large heads, powerful mandibles and
well-developed legs, but the body-segments are feebly chitinized, and
the tail-end is swollen. They feed in wood or spend an underground
life devouring roots or animal excrement.
The _Lucanidae_ or stag beetles (figs. 1 and 25) have the terminal
antennal segments pectinate, and so arranged that the comb-like part
of the feeler cannot be curled up, while the elytra completely cover
the abdomen. There are about 600 species in the family, the males
being usually larger than the females, and remarkable for the size of
their mandibles. In the same species, however, great variation occurs
in the development of the mandibles, and the breadth of the head
varies correspondingly, the smallest type of male being but little
different in appearance from the female. The larvae of _Lucanidae_
live within the wood of trees, and may take three or four years to
attain their full growth. The _Passalidae_ are a tropical family of
beetles generally considered to be intermediate between stag-beetles
and chafers, the enlarged segments of the feeler being capable of
close approximation.
The _Scarabaeidae_ or chafers are an enormous family of about 15,000
species. The plate-like segments of the feeler (fig. 26, b, c) can be
brought close together so as to form a club-like termination; usually
the hinder abdominal segments are not covered by the elytra. In this
family there is often a marked divergence between the sexes; the
terminal antennal segments are larger in the male than in the female,
and the males may carry large spinous processes on the head or
prothorax, or both. These structures were believed by C. Darwin to be
explicable by sexual selection. The larvae have the three pairs of
legs well developed, and the hinder abdominal segments swollen. Most
of the _Scarabaeidae_ are vegetable-feeders, but one section of the
family--represented in temperate countries by the dor-beetles
(_Geotrupes_) (fig. 28) and _Aphodius_, and in warmer regions by the
"sacred" beetles of the Egyptians (_Scarabaeus_) (fig. 27), and allied
genera--feed both in the adult and larval stages, on dung or decaying
animal matter. The heavy grubs of _Geotrupes_, their swollen tail-ends
black with the contained food-material, are often dug up in numbers in
well-manured fields. The habits of _Scarabaeus_ have been described in
detail by J. H. Fabre. The female beetle in spring-time collects dung,
which she forms into a ball by continuous rolling, sometimes assisted
by a companion. This ball is buried in a suitable place, and serves
the insect as a store of food. During summer the insects rest in their
underground retreats, then in autumn they reappear to bury another
supply of dung, which serves as food for the larvae. Fabre states that
the mother-insect carefully arranges the food-supply so that the most
nutritious and easily digested portion is nearest the egg, to form the
first meal of the young larva. In some species of _Copris_ it is
stated that the female lays only two or three eggs at a time, watching
the offspring grow to maturity, and then rearing another brood.
[Illustration: FIG. 25.--_Cladognathus cinnamomeus_. Java.]
[Illustration: FIG. 26.--_Melolontha fullo_ (Cockchafer). S. Europe,
b, Antenna of male; c, antenna of female.]
[Illustration: FIG. 27.--_Scarabaeus Aegyptiorum_. Africa.]
[Illustration: FIG. 28.--_Geotrupes Blackburnei_. N. America.]
[Illustration: FIG. 29.--_Phaneus Imperator_. S. America.]
[Illustration: FIG. 30.--_Cetonia Baxii_. W. Africa.]
Among the vegetable-feeding chafers we usually find that while the
perfect insect devours leaves, the larva lives underground and feeds
on roots. Such are the habits of the cockchafer (_Melolontha
vulgaris_) and other species that often cause great injury to farm and
garden crops (see CHAFER). Many of these insects, such as the species
of _Phanaeus_ (fig. 29) and _Cetonia_ (fig. 30), are adorned with
metallic or other brilliant colours. The African "goliath-beetles"
(fig. 31) and the American "elephant-beetles" (_Dynastes_) are the
largest of all insects.
ANCHISTOPODA.--The families of beetles included by Kolbe in this group
are distinguished by the possession of six malpighian tubes, and a
great reduction in one or two of the tarsal segments, so that there
seem to be only four or three segments in each foot; hence the names
_Tetramera_ and _Trimera_ formerly applied to them. The larvae have
soft-skinned bodies sometimes protected by rows of spiny tubercles,
the legs being fairly developed in some families and greatly reduced
or absent in others. As might be expected, degeneration in larval
structure is correlated with a concealed habit of life.
The _Coccinellidae_, or ladybirds (fig. 32), are a large family of
beetles, well known by their rounded convex bodies, usually shining
and hairless. They have eleven segments to the feeler, which is
clubbed at the tip, and apparently three segments only in each foot.
Ladybirds are often brightly marked with spots and dashes, their
coloration being commonly regarded as an advertisement of inedibility.
The larvae have a somewhat swollen abdomen, which is protected by
bristle-bearing tubercles. Like the perfect insects, they are
predaceous, feeding on plant-lice (_Aphidae_) and scale insects
(_Coccidae_). Their role in nature is therefore beneficial to the
cultivator. The _Endomychidae_ (fig. 33), an allied family, are mostly
fungus-eaters. In the _Erotylidae_ and a few other small related
families the feet are evidently four-segmented.
[Illustration: FIG. 31.--_Goliathus giganteus_ (Goliath Beetle).]
[Illustration: FIG. 32.--_Anatio ocellata_ (Eyed Ladybird). Europe.]
[Illustration: FIG. 33.--_Endomychus coccineus_. Europe.]
[Illustration: FIG. 34.--_Sagra cyanea_. W. Africa.]
[Illustration: FIG. 35.--_Eumorphus ivguttatus_. Sumatra.]
[Illustration: FIG. 36.--_Lophonocerus barbicornis_. S. America.]
The _Chrysomelidae_, or leaf-beetles (figs. 34, 35), are a very large
family, with "tetramerous" tarsi; there seem to be only four segments
to the foot, but there are really five, the fourth being greatly
reduced. The mandibles are strong, adapted for biting the vegetable
substances on which these beetles feed, and the palps of the second
maxillae have three segments. Most of the _Chrysomelidae_ are metallic
in colour and convex in form; in some the head is concealed beneath
the prothorax, and the so-called "tortoise" beetles (_Cassidinae_)
have the elytra raised into a prominent median ridge. The most active
form of larva found in this family resembles in shape that of a
ladybird, tapering towards the tail end, and having the trunk segments
protected by small firm sclerites. Such larvae, and also many with
soft cuticle and swollen abdomen--those of the notorious "Colorado
beetle," for example--feed openly on foliage. Others, with soft,
white, cylindrical bodies, which recall the caterpillars of moths,
burrow in the leaves or stems of plants. The larvae of the
tortoise-beetles have the curious habit of forming an umbrella-like
shield out of their own excrement, held in position by the upturned
tail-process. The larvae of the beautiful, elongate, metallic
_Donaciae_ live in the roots and stems of aquatic plants, obtaining
thence both food and air. The larva pierces the vessels of the plant
with sharp processes at the hinder end of its body. In this way it is
believed that the sub-aqueous cocoon in which the pupal stage is
passed becomes filled with air.
The _Cerambycidae_, or longhorn beetles, are recognizable by their
slender, elongate feelers, which are never clubbed and rarely serrate.
The foot has apparently four segments, as in the _Chrysomelidae_. The
beetles are usually elongate and elegant in form, often adorned with
bright bands of colour, and some of the tropical species attain a very
large size (figs. 36, 37). The feelers are usually longer in the male
than in the female, exceeding in some cases by many times the length
of the body. The larvae have soft, fleshy bodies, with the head and
prothorax large and broad, and the legs very much reduced. They live
and feed in the wood of trees. Consequently, beetles of this family
are most abundant in forest regions, and reach their highest
development in the dense virgin forests of tropical countries, South
America being particularly rich in peculiar genera.
[Illustration: FIG. 37.--_Phryneta aurocincta_. West Africa.]
The _Bruchidae_, or seed-beetles, agree with the two preceding
families in tarsal structure; the head is largely hidden by the
pronotum, and the elytra are short enough to leave the end of the
abdomen exposed (fig. 38). The development of the pea and bean-beetles
has been carefully studied by C. V. Riley, who finds that the young
larva, hatched from the egg laid on the pod, has three pairs of legs,
and that these are lost after the moult that occurs when the grub has
bored its way into the seed. In Great Britain the beetle, after
completing its development, winters in the seed, waiting to emerge and
lay its eggs on the blossom in the ensuing spring.
[Illustration: FIG. 38.--_Bruchus piei_ (Pea Beetle.) Europe.]
[Illustration: FIG. 39.--_Platyrrhinus latirostris_. Europe.]
RHYNCHOPHORA.--The _Rhynchophora_ are a group of beetles easily
recognized by the elongation of the head into a beak or snout, which
carries the feelers at its sides and the jaws at its tip. The third
tarsal segment is broad and bi-lobed, and the fourth is so small that
the feet seem to be only four-segmented. There are six malpighian
tubes. The ventral sclerite of the head-skeleton (gula), well
developed in most families of beetles, is absent among the
_Rhynchophora_, while the palps of the maxillae are much reduced. The
larvae have soft, white bodies and, with very few exceptions, no legs.
[Illustration: FIG. 40.--_Brenthus anchorago_. Tropical Countries.]
[Illustration: FIG. 41.--_Otiorrhynchus ligustici_. Europe.]
[Illustration: FIG. 42.--_Lixus paraplecticus_. Europe.]
Of the four families included in this group, the _Anthribidae_ (fig.
39) have jointed, flexible palps, feelers--often of excessive
length--with a short basal segment, and the three terminal segments
forming a club, and, in some genera, larvae with legs. There are
nearly 1000 known species, most of which live in tropical countries.
The _Brenthidae_ are a remarkable family almost confined to the
tropics; they are elongate and narrow in form (fig. 40), with a
straight, cylindrical snout which in some male beetles of the family
is longer than the rest of the body.
[Illustration: FIG. 43.--_Scolytus ulmi_. (Bark Beetle). Europe.]
The _Curculionidae_, or weevils (q.v.), comprising 23,000 species, are
by far the largest family of the group. The maxillary palps are short
and rigid, and there is no distinct labrum, while the feelers are
usually of an "elbowed" form, the basal segment being very elongate
(figs. 41, 42). They are vegetable feeders, both in the perfect and
larval stages, and are often highly injurious. The female uses her
snout as a boring instrument to prepare a suitable place for
egg-laying. The larvae (fig. 3) of some weevils live in seeds; others
devour roots, while the parent-beetles eat leaves; others, again, are
found in wood or under bark. The _Scolytidae_, or bark-beetles, are a
family of some 1500 species, closely allied to the _Curculionidae_,
differing only in the feeble development of the snout. They have
clubbed feelers, and their cylindrical bodies (fig. 43) are well
adapted for their burrowing habits under the bark of trees. Usually
the mother-beetle makes a fairly straight tunnel along which, at short
intervals, she lays her eggs. The grubs, when hatched, start galleries
nearly at right angles to this, and when fully grown form oval cells
in which they pupate; from these the young beetles emerge by making
circular holes directly outward through the bark.
BIBLIOGRAPHY.--In addition to what may be found in numerous important
works on the Hexapoda (q.v.) as a whole, such as J. O. Westwood's
_Modern Classification of Insects_, vol. i. (London, 1838); J. H.
Fabre's _Souvenirs Entomologiques_ (Paris, 1879-1891); D. Sharp's
contribution to the Cambridge Natural History (vol. vi., London,
1899); and L. C. Miall's _Aquatic Insects_ (London, 1895), the special
literature of the _Coleoptera_ is enormous. Classical anatomical
memoirs are those of L. Dufour (_Ann. Sci. Nat._ ii., iii., iv., vi.,
viii., xiv., 1824-1828); _Ib._ (ser. 2, Zool.) i., 1834; and H. E.
Strauss-Durkheim, _Anatomie comparee des animaux articulees_ (Paris,
1828).
The wings of _Coleoptera_ (including the elytra) are described and
discussed by F. Meinert (_Entom. Tijdsk._ v., 1880); C. Hoffbauer
(_Zeit. f. wissen. Zool._ liv., 1892); J. H. Comstock and J. G.
Needham (_Amer. Nat._ xxxii., 1898); and W. L. Tower (_Zool. Jahrb.
Anat._ xvii., 1903). The morphology of the abdomen, ovipositor and
genital armature is dealt with by K. W. Verhoeff (_Ent. Nachtr._ xx.,
1894, and _Arch. f. Naturg._ lxi., lxii., 1895-1896); and B.
Wandolleck (_Zool. Jahrb. Anat._ xxii., 1905).
Luminous organs are described by H. von Wielowiejski (_Zeits. f.
wissen. Zool._ xxxvii., 1882); C. Heinemann (_Arch. f. mikr. Anat._
xxvii., 1886); and R. Dubois (_Bull. soc. zool. France_, 1886); and
stridulating organs by C. J. Gahan (_Trans. Entom. Soc._, 1900). See
also C. Darwin's _Descent of Man and Selection in Relation to Sex_
(London, 1871).
Many larvae of _Coleoptera_ are described and beautifully figured by
J. C. Schiodte (_Naturh. Tidsskr._ i.-xiii., 1861-1872).
Hypermetamorphosis in the _Meloidae_ is described by G. Newport
(_Trans. Linn. Soc._ xx., xxi., 1851-1853); C. V. Riley (_Rep. U.S.
Entom. Comm._ i., 1878); J. H. Fabre (_Ann. Sci. Nat._ (4), ix., xix.,
1848-1853); H. Beauregard (_Les Insectes vesicants_, Paris, 1890); and
A. Chabaud (_Ann. Soc. Ent. France_, lx., 1891); in the _Bruchidae_ by
Riley (_Insect Life_, iv., v., 1892-1893); and in the _Strepsiptera_
(_Stylopidae_) by K. T. E. von Siebold (_Arch. f. Naturg._ ix., 1843);
N. Nassonov (_Bull. Univ. Narsovie_, 1892); and C. T. Brues (_Zool.
Jahrb. Anat._ xiii., 1903).
For various schemes of classification of the _Coleoptera_ see E. L.
Geoffroy (_Insectes qui se trouvent aux environs de Paris_, Paris,
1762); A. G. Olivier (_Coleopteres_, Paris, 1789-1808); W. S. MacLeay
(_Annulosa Javanica_, London, 1825); the general works of Westwood and
Sharp, mentioned above; M. Gemminger and B. de Harold (_Catalogus
Coleopterorum_, 12 vols., Munich, 1868-1872); T. Lacordaire and F.
Chapuis (_Genera des Coleopteres_, 10 vols., Paris, 1854-1874); J. L.
Leconte and G. H. Horn (_Classification of Coleoptera of N. America_,
Washington, Smithsonian Inst., 1883); L. Ganglbauer (_Die Kafer von
Mitteleuropa_, Vienna, 1892, &c.); A. Lameere (_Ann. Soc. Ent. Belg._
xliv., xlvii., 1900-1903); and H. J. Kolbe (_Arch. f. Naturg._ lxvii.,
1901).
For the British species, W. W. Fowler (_Coleoptera of the British
Islands_, 5 vols., London, 1887-1891) is the standard work; and W. F.
Johnson and J. N. Halbert's "Beetles of Ireland" (_Proc. R. Irish
Acad._, 3, vi., 1902) is valuable faunistically. Among the large
number of systematic writers on the order generally, or on special
families, may be mentioned D. Sharp, T. V. Wollaston, H. W. Bates, G.
C. Champion, E. Reitter, G. C. Crotch, H. S. Gorham, M. Jacoby, L.
Fairmaire and C. O. Waterhouse. (G. H. C.)