the food put out for poultry. They are destructive also to tame
pigeons and their eggs, but particularly to young squabs. They climb
the wire netting and gain entrance to the cages through the same
openings by which the pigeons come and go. Fanciers are often put to
great trouble to protect their pigeons from rats, and because of these
pests some of them have abandoned the business.
GAME AND WILD BIRDS.
The rat is the most serious pest in European game preserves. A writer
in Chambers’s Journal says:
In a closely preserved country at the end of an average year the
game suffers more from the outlying rats of the lordship than from
the foxes and mustelines together. The solitary rats, whether males
or females, are the curse of a game country. They are most difficult
to detect, for in a majority of cases their special work is supposed
to be done by hedgehog, weasels, or stoat.[CF]
Footnote CF:
Chambers’s Journal, vol. 82, p. 64, January, 1905.
The propagation of game birds is becoming a promising industry in the
United States. The difficulties of the business are not yet fully
known, but the rat is an enemy with which the raiser of game will have
to contend. The animal has already proved itself a foe in American
pheasantries.
Our wild native game birds are less subject to rat depredations than
birds kept in confinement. The nests of ruffed grouse are in
woodlands; those of the prairie hen and related species are on plains
remote from the haunts of rats. The quail, however, often makes its
nest within the summer range of rats, which destroy many of its eggs.
Rats are said often to destroy the nests of wild ducks, woodcock, and
other marsh birds. Terns have been entirely driven from their nesting
grounds in this way. In England the common tern was extirpated from
the Thames marshes; and on Loggerhead Key, Tortugas Islands, off the
Florida coast, rats recently nearly exterminated a colony of least
terns by destroying the eggs.
The nests of many ground-nesting and other song birds are robbed by
rats. Crows, jays, snakes, and skunks are blamed for most of the
destruction and the actual offender seldom suspected. While the other
animals named do part of the mischief, the rat is a more serious foe
of song and game birds than any of these.
FRUITS AND VEGETABLES.
A well-known form of damage by rats is the destruction of fruits and
vegetables in cellars and pits. Apparently no garden vegetable or
common fruit is exempt from attack. But the rat does not confine its
depredations to stored fruits and vegetables. It attacks ripe
tomatoes, melons, cantaloupes, squashes, pumpkins, sweet corn, and
many other vegetables in the field; and often the depredations are
attributed to rabbits or other animals, which may or may not be
concerned in the mischief.
Rats are fond of the small fruits, eating not only the fallen but
climbing vines and canes to obtain the ripe grapes or berries. They
eat also apples, pears, cherries, and other fruits. The brown rat,
while not so expert as the black or the roof rat, readily climbs trees
and obtains fruit even at the extremities of the branches.
Among tropical fruits injured by rats are oranges, bananas, figs,
dates, cocoanuts, and especially the pods of cacao (_Theobroma
cacao_), from which chocolate is manufactured. H. N. Riddey, writing
of his experiences on the island of Fernando do Noronha, South
America, mentions the destructiveness of rats in this penal colony.
They climb the cocoanut palms and papaw trees to devour the fruit, and
do mischief in melon patches. To lessen the evil, each convict was
required to bring in a certain number of dead rats, and battues were
held monthly to satisfy the requirement. Sometimes the number killed
in a single hunt reached 20,000.[CG]
Footnote CG:
Zoologist, vol. 46, p. 46, 1888.
Fruits and vegetables grown under glass are subject to injury by rats.
The animals usually find entrance to greenhouses by way of openings
for pipes or drains.
FLOWERS AND BULBS.
Rats attack seeds, bulbs, and the leaves, stems, and flowers of
growing plants, whether in the greenhouse, propagating pits, or
elsewhere. Of flowering bulbs, the tulip suffers most from rats.
Hyacinths also are eaten; but, probably because they are slightly
poisonous, narcissus and daffodil bulbs escape injury. Rats eat pinks,
carnations, and roses, cutting the stems off clean. They denude
geraniums of both flowers and leaves. They attack the choicest blooms
of chrysanthemums and carnations in markets, stores, and exhibition
rooms, causing heavy losses.
FIRES.
Rats and mice cause many fires. Several specific instances have been
reported by the fire department of the city of Washington within the
past two or three years. It is likely that some of these fires are
caused by rats gnawing matches. The animals are fond of paraffin,
which is often used to protect match heads. They carry the matches to
their nests, which are composed of paper and other combustible
materials, and the conditions for a conflagration are ready. Since the
heads of matches contain from 14 to 17 per cent of phosphorus, actual
gnawing is not required to ignite them, but heat or friction from any
cause may suffice.
Fires in mills or warehouses have sometimes been traced to the
spontaneous ignition of oily or fatty rags and waste carried under
floors by rats. Cotton and woolen mills are said to be peculiarly
subject to fires of this kind.
Sometimes rats cause fires by gnawing through the lead pipes leading
to the gas meter. Workmen or others, searching for the leak,
accidentally ignite the gas. Phillips’s warehouse, London, was twice
badly damaged by fires originating in this way, and in several
instances the sleeping inmates of houses have been in danger of
asphyxiation by gas freed in this manner.
The most common way in which rats and mice cause fires is by the
destruction of the covering of electric light wires under floors or in
partition walls. A considerable percentage of the enormous fire losses
in the United States is caused by defective insulation of wires. After
wires are once in position rats are the chief agents in impairing the
insulation. These animals do much mischief also by gnawing off the
coverings of telephone wires. In the case of electric light wires the
covering is probably used by the rats for nesting material, but
frequently the paraffin in the insulation is the object of attack.
BUILDINGS AND FURNITURE.
Rats seem to be able to gnaw through almost any common material except
stone, hard brick, cement, glass, and iron; neither wood nor mortar
suffice to keep them out of bins or rooms. They sometimes gnaw through
walls or doors in a single night. In the same way they enter chests,
wardrobes, bookcases, closets, barrels, and boxes. Almost every old
dwelling bears evidence of its present or former occupancy by rats.
Often the depreciation of houses and furniture is largely due to marks
left upon them by rats—marks that paint and varnish can not hide.
Damage to dwellings by rats is a large item. The decay of sills and
floors is hastened by contact with moist soil brought up from rat
burrows. Ceilings, wall decorations, and floor coverings are flooded
by leaks in lead pipes or wooden tanks gnawed by rats. Bricked areas
and even foundations are undermined and ruined by rats. All this is
real waste and a constant drain on the resources of the country.
MISCELLANEOUS.
A few instances of miscellaneous damage by rats may be mentioned to
show the great variety of mischief chargeable to the animals.
A Washington, D. C., merchant reported that at one time rats in his
store destroyed 50 dozen brooms worth $2.50 a dozen. In another store,
in a single night, they broke $500 worth of fine chinaware on shelves
and tables. A dealer in harness reported the loss of $400 worth of
collars in one season. The manager of a restaurant complained of an
average loss of $30 a month in table linen ruined by rats and mice. A
hotel reported the destruction of $75 worth of linen in a month.
At Mobile, Ala., in March, 1908, lost jewelry worth $400 was recovered
from a rat’s nest in the home of Señor Viada.
In London rats at one time killed all but 11 out of an aviary of 366
birds.
At Hamburg, Germany, Carl Hagenbeck once had to kill three young
African elephants because rats had gnawed their feet, inflicting
incurable wounds.
Rats often gnaw the hoofs of horses until they bleed. They kill young
lambs and pigs, and have been known to gnaw holes in the bodies of
very fat swine, causing death.
Like the muskrat, the brown rat often burrows into embankments and
dams, causing serious breaks.
The rat is one of the greatest enemies with which the sugar planter
has to contend, destroying acres of growing cane.
In rice plantations rats not only break down and destroy the growing
crops, but burrow into the dikes and flood the fields at the wrong
season.
On the London docks and on shipboard ivory is often badly damaged by
rats. They select for attack the greenest tusks, which are the more
valuable.
Mail sacks and other kinds of bagging are greatly injured by rats. The
consequent loss and necessary outlay for repairs are a large item in
post-office expenditures and in mills and other places where bagging
is used.
About the year 1616 rats caused a two years’ famine in the Bermudas.
In the southern Deccan and Mahratta districts of India rats ate a
large part of the scant crops of 1878 and 1879, and were regarded as
in a great measure responsible for the severe famine which
followed.[CH] A writer in Chambers’s Journal stated that the Dutch
abandoned the Isle of France (Mauritius) in 1610 because of the great
abundance of rats.[CI]
Footnote CH:
Brit. Med. Journ., p. 623, September 15, 1905.
Footnote CI:
Chambers’s Journal, vol. 21, p. 244, 1854.
AMOUNT OF LOSSES CAUSED BY RATS.
The damage done by a single rat varies greatly with the circumstances.
We have already stated that the cost of feeding a rat on grain varies
from 60 cents to $2 a year. Assuming that much of the rat’s food is
waste, each rat on a farm will cause a loss of over 50 cents a year.
In cities the damage by a single rat probably averages more than in
the country. Hotel managers and restaurant keepers state that $5 a
year is a low estimate of the loss inflicted by a rat. In making an
estimate it should be remembered that the rat is to be charged not
only with the food it actually consumes but also with what it destroys
or pollutes and renders unfit for use.
If an accurate census of the rats in the United States were possible,
and if the minimum average loss caused by a rat were known, an
estimate of the total annual losses from their depredations could be
made. It was on such a minimum basis that the Incorporated Society for
the Destruction of Vermin arrived at their total estimate of
£15,000,000 ($73,000,000) as the yearly losses from rats in Great
Britain and Ireland. Three propositions were assumed: first, that in
cities and villages the number of rats equals the population; second,
that in the country there is at least one rat for every acre of
cultivated land; third, that each rat in the kingdom inflicts a damage
of at least a farthing per day. Circulars asking whether these
assumptions are excessive were distributed throughout the country.
From 90 to 99 per cent of the replies fully indorsed each of the
assumptions.
It can readily be seen that the English basis of estimate would not
apply to farm conditions in the United States, where the area in the
twelve leading crops alone is over 250,000,000 acres. On a basis of a
rat per acre and damage of a farthing per day the annual loss on this
area would be $450,000,000, a sum much too great for serious
consideration. However, in the more thickly populated parts of the
country an estimate of one rat per acre would not be excessive; and it
is probable that in most of our cities there are quite as many rats as
people. Yet it would be unsafe, owing to our vast territory and
varying conditions, to make these assumptions the basis for
conclusions.
Over a year ago the writer made an attempt to investigate actual
conditions, and thus arrive at an estimate of the total damage by rats
in the cities of Washington and Baltimore. From the data obtained the
direct annual damage in the two cities was calculated at $400,000 and
$700,000, respectively. The Census Bureau in 1906 estimated the
population of these cities at 308,000 and 554,000, respectively. If
the estimates of damage were correct, the average loss for each person
is $1.27 a year; and, on the same basis, the 28,000,000 of urban
population in the United States (census of 1900) sustains an annual
direct injury of $35,000,000 from rats. This is considerably lower
than on the English assumption, which would make the losses in our
cities over $50,000,000.
Denmark (population 2,500,000) has an estimated rat bill of about
$3,000,000 a year, or $1.20 a person. Germany (population 56,000,000)
is said to sustain a loss from rats of 200,000,000 marks ($47,640,000)
a year, or about 85 cents for each person. The per capita estimate for
the United Kingdom is about double that made for Germany. In France
the loss from rats and mice for a single year (1904) was placed at
$38,500,000, or a little over a dollar for each of its 38,000,000
inhabitants. These estimates are supposed to include only direct
losses, but they vary enough to show that no common basis can be
assumed for all countries. With present information, therefore, any
attempt to state the amount of loss from rats in the United States
would be largely guesswork. Considering the population and wealth of
the country, however, and the vast area over which rats are abundant,
it is not unreasonable to conclude that in the United States the
losses from rats amount to much more than in any of the other
countries named.
INDIRECT LOSSES.
To the direct losses caused by rats must be added the cost of fighting
the animals and of protecting property from them. In our larger cities
a number of so-called expert rat catchers are to be found, who operate
with dogs, ferrets, traps, poisons, or other means, and who have an
extensive clientage among merchants, hotel managers, and others. These
pay the rat catcher a yearly or monthly stipend to keep their premises
free of rats and mice. Some of the large establishments pay $200 to
$600 yearly for such service. While the agreements are seldom kept in
full, the clients are usually satisfied that results warrant the
expense. Even when no contractor is employed, merchants are at expense
for traps, poisons, the keep of cats or dogs, and other means of
fighting rats. The same is true in less degree of nearly every
householder.
The cost of protecting property from rats is no small item. It
increases the expense of nearly all building, but it greatly reduces
direct losses from the animals. The economy of rat-proof construction
is everywhere manifest, in city or country, and the necessity for it
can not be too strongly emphasized.
Depreciation of property and loss of rents and custom are items not
generally thought of in connection with rat damage. A few years ago
the writer knew of almost an entire block of city houses that remained
untenanted for several months, because infested by rats. As the houses
were otherwise desirable, the loss of rent to the owners was probably
nearly $2,000. The presence of rats in markets, hotels, and
restaurants inevitably results in loss of custom, besides the direct
damage by the rodents.
From every point of view the keeping of rats is exceedingly expensive,
and the sooner our population can be made to realize the enormous
drain upon our resources caused by these rodents the sooner can
concerted measures for their destruction be made effective.
THE RAT IN RELATION TO INTERNATIONAL SANITATION.
By Asst. Surg.-Gen., JOHN W. KERR,
_Public Health and Marine-Hospital Service_.
Rats, like man, had their origin in Asia, from which continent they
have finally become disseminated throughout the world. They, too, like
man, are great travelers, and therefore prey on the commerce of the
ships in which they are carried. For this reason, and on account of
the fact that they are subject to plague and may transmit the disease
from one country to another, these animals have an influence on
international policy, and their control aboard ships is an
international problem.
It has been estimated that there are as many rats as there are human
beings, and that each rat causes each day a loss by the destruction of
material of at least half a cent.
Assuming that the rat population aboard ships is as great as the human
population—and my experience gained during the fumigation of ships to
kill rats convinces me that on the whole it is greater—some idea may
be had of the enormous migrations of rats and the toll they exact for
food from international commerce. Some idea can also be had of the
danger of rats in transmitting plague when it is remembered that 51
countries have been infected with the disease since the present
pandemic began in Canton, China, in 1894, and when it is known that at
least 146 ships have had plague infection on board during that time.
During the International Sanitary Conference of Paris in 1903 the
influence of the rat in transmitting plague was borne in mind, and the
international sanitary agreement, which was signed ad referendum
December 3, 1903, requires the destruction of rats aboard
plague-infected ships, recommends it on ships suspected of being
plague infected, and permits it on ships indemne from plague. The ship
is considered indemne from plague which, although coming from an
infected port, has had neither death nor case on board either before
departure, during the voyage, or at the moment of arrival.
The International Sanitary Convention signed at Washington, October
14, 1905, follows the text of the Paris convention, with respect to
plague, consequently embodying similar requirements and
recommendations as follows:
ART. XX. _Classification of ships._—A ship is considered as infected
which has plague, cholera, or yellow fever on board, or which has
presented one or more cases of plague or cholera within seven days,
or a case of yellow fever at any time during the voyage.
A ship is considered as suspected on board of which there have been
a case or cases of plague or cholera at the time of departure or
during the voyage, but no new case within seven days; also such
ships as have lain in such proximity to the infected shore as to
render them liable to the access of mosquitoes.
The ship is considered indemne which, although coming from an
infected port, has had neither death nor case of plague, cholera, or
yellow fever on board, either before departure, during the voyage,
or at the time of arrival, and which in the case of yellow fever has
not lain in such proximity to the shore as to render it liable, in
the opinion of the sanitary authorities, to the access of
mosquitoes.
ART. XXI. Ships infected with plague are to be subjected to the
following regulations:
1. Medical visit (inspection).
2. The sick are to be immediately disembarked and isolated.
3. Other persons should also be disembarked, if possible, and
subjected to an observation,[CJ] which should not exceed five days,
dating from the day of arrival.
Footnote CJ:
The word “observation” signifies isolation of passengers, either
on board ship or at a sanitary station, before being given free
pratique.
4. Soiled linen, personal effects in use, the belongings of crew[CK]
and passengers which, in the opinion of the sanitary authorities are
considered as infected, should be disinfected.
Footnote CK:
The term “crew” is applied to persons who may make, or who have
made, a part of the personnel of the vessel and of the
administration thereof, including stewards, waiters, “cafedji,”
etc. The word is to be construed in this sense wherever employed
in the present convention.
5. The parts of the ship which have been inhabited by those stricken
with plague, and such others as, in the opinion of the sanitary
authorities, are considered as infected, should be disinfected.
6. The destruction of rats on shipboard should be effected before or
after the discharge of cargo, as rapidly as possible, and in all
cases with a maximum delay of forty-eight hours, care being taken to
avoid damage of merchandise, the vessel, and its machinery.
For ships in ballast, this operation should be performed immediately
before taking on cargo.
ART. XXII. Ships suspected of plague are to be subjected to the
measures which are indicated in Nos. 1, 4, and 5 of Article XXI.
Further, the crew and passengers may be subjected to observation,
which should not exceed five days, dating from the arrival of the
ship. During the same time the disembarkment of the crew may be
forbidden, except for reasons of duty.
The destruction of rats on shipboard is recommended. This
destruction is to be effected before or after the discharge of
cargo, as quickly as possible, and in all cases with a maximum delay
of forty-eight hours, taking care to avoid damage to merchandise,
ships, and their machinery.
For ships in ballast this operation should be done, if done at all,
as early as possible, and in all cases before taking on cargo.
ART. XXIII. Ships indemne from plague are to be admitted to free
pratique immediately, whatever may be the nature of their bill of
health.
The only regulation which the sanitary authorities at a port of
arrival may prescribe for them consists of the following measures:
1. Medical visit (inspection).
2. Disinfection of soiled linen, articles of wearing apparel, and
the other personal effects of the crew and passengers, but only in
exceptional cases when the sanitary authorities have special reason
to believe them infected.
3. Without demanding it as a general rule, the sanitary authorities
may subject ships coming from an infected port to a process for the
destruction of the rats on board before or after the discharge of
cargo. This operation should be done as soon as possible, and in all
cases should not last more than twenty-four hours, care being taken
to avoid damaging merchandise, ships, and their machinery, and
without interfering with the passing of passengers and crew between
the ship and the shore. For ships in ballast this procedure, if
practiced, should be put in operation as soon as possible, and in
all cases before taking on cargo.
When a ship coming from an infected port has been subjected to a
process for the destruction of rats, this process should only be
repeated if the ship has touched meanwhile at an infected port, and
has been alongside a quay in such port, or if the presence of sick
or dead rats on board is proven.
The crew and passengers may be subjected to a surveillance, which
should not exceed five days, to be computed from the date when the
ship sailed from the infected port. The landing of the crew may
also, during the same time, be forbidden except for reasons of duty.
Competent authority at the port of arrival may always demand, under
oath, a certificate of the ship’s physician, or in default of a
physician, of the captain, setting forth that there has not been a
case of plague on board since departure, and that no marked
mortality among the rats has been observed.
ART. XXIV. When upon an indemne ship rats have been recognized as
pest stricken as a result of bacteriological examination, or when a
marked mortality has been established among these rodents, the
following measures should be applied:
1. Ships with plague-stricken rats:
(_a_) Medical visit (inspection).
(_b_) Rats should be destroyed before or after the discharge of
cargo, as rapidly as possible, and in all cases with a delay not to
exceed forty-eight hours; the deterioration of merchandise, vessels,
and machinery to be avoided. Upon ships in ballast, this operation
should be performed as soon as possible, and in all cases before
taking on cargo.
(_c_) Such parts of the ship and such articles as the local sanitary
authority regards as infected, shall be disinfected.
(_d_) Passengers and crew may be submitted to observation, the
duration of which should not exceed five days, dating from the day
of arrival, except in special cases, where the sanitary authority
may prolong the observation to a maximum of ten days.
2. Ships where a marked mortality among rats is observed:
(_a_) Medical visit (inspection).