The Argentine ant : distribution and control in the United States

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Do not assume content reflects current
scientific knowledge, policies, or practices.

f°

| BULLETIN Nol 3 377

Contribution from the Bureau of Eatomolodyo
L. O. HOWARD, Chief

Washington, D. C. PROFESSIONAL PAPER rome i8, 1916

THE ARGENTINE ANT:' DISTRIBUTION AND CON-
TROL IN THE UNITED STATES.

By Ernest R. Barser, Scientific Assistant, Southern Field Crop Insect Investi-

gations.

CONTENTS.
Page. | Page.
Present known distribution in the ETA GS yee ee See ee a eee ee 6
Southern States] 222 =) Ss 22) bite history 2222s se Se eae a G
DISPERSION sae Ae ee a Si NEG Uae CONG Oise eee 9
HE conomicmmporrance 22 oss eee ee 5) 1 Repression. = 2. 2 s2 2 ee Sa 10

INTRODUCTION.

The Argentine ant? is one of the most serious of household pests.
Any exposed food or food refuse in the infested sections attracts the
workers of this species in abundance, and residents and keepers of
grocery stores, meat markets, confectioneries, etc., must either suffer
considerably or almost constantly use poison or barriers of various
kinds. If its activities were confined to the household only, the prob-
lem of controlling the Argentine ant would be sufficiently difficult,
but in common with some other ants it has the habit of protecting
mealybugs and aphids and thus indirectly becomes a pest of crops.

The problem is more serious from the fact that the species is
steadily spreading in all directions throughout the Southern States.
It is practically certain that it was introduced into this country at
New Orleans, in ships which brought coffee from ports in Brazil,
although the exact date of this introduction will always remain
in doubt.

The Argentine ant was first observed in New Orlane 4 in 1891 by
Mr. Edward Foster. At that time he records it in small numbers:

1 The work of the Bureau of Entomology on the Argentine ant is divided into two parts.
One part deals with the ant as a general pest, its distribution, and relation to the cultiva-
tion of sugar cane. The other part relates to the special problem of control in citrus
groves. This phase will be treated in another publication. The work reported in this ~
paper does not include reference to conditions in California, parts of which State are alsa
infested by the Argentine ant.

2Tridomyrmez humilis Mayr.

$Foster, E. The introduction of Iridomyrmex humilis (Mayr) into New Orleans. Jour.
Heon. Ent., v. 1, no. 5, p. 289-293. 1908.

41860°—Bull. 377—16——-1

a BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE,

nine blocks east of the wharves at which the coffee ships usually dis-
charged their cargoes. It may be surmised, from the knowledge we
have since gained from studying the natural dispersion of this insect,
that it has been in the country for about 45 years. During that period
it has expanded from the original colony to myriads of colonies,
extending its area of distribution into nine Southern States, the
many infestations covering a total area of considerably more than a
thousand square miles.

PRESENT KNOWN DISTRIBUTION IN THE SOUTHERN STATES.
Newell and Barber,’ writing in 1913, recorded the known distri-
bution in the Southern States as confined to Louisiana, Mississippi,

Fic. 1—Map showing the distribution of the Argentine ant in 1913 (inner line of small
dashes) and at the end of 1915 (outer line of longer dashes). (Original.) The outer
line has been drawn merely to connect the outlying points. It incloses some territory in
which the ant is not known to occur, as, for instance, western Florida.

and Alabama, and established the limits of this dispersion from

Montgomery, Ala., on the east, to Lake Charles, La., on the west, a

distance of 380 miles, and from Delta, La., on the north, to the

mouth of the Mississippi River, a distance of 250 miles. At the
present time the limits of the distribution are from Houston, Tex.,
on the west, to Wilmington, N. C., on the east, and from Nashville,

Tenn., to the mouth of the Mississippi River, a distance of 1,100 miles

east and west and 500 miles north and south (map, fig. 1). Among

the cities known to be infested are Houston, Tex., Shreveport, La.,

1 Newell, Wilmon, and Barber, T. C. The Argentine Ant. U. S. Dept. Agr. Bur. Ent,
Bille pola. OLS,

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PT oe 1 eh a

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 3

Texarkana, Ark.. Nashville, Tenn., Memphis, Tenn., Augusta, Ga.,
Atlanta, Ga., Charleston, S. C., and Wilmington, N.C. |

DISPERSION. .

Under natural conditions the Argentine ant spreads very slowly, and
this spread is controlled to a large degree by the available food supply.
Like most other species of ants, the Argentine ant is a very indus-
trious forager, and a shortage of food tends to hasten its dispersion.
In October, 1914, a small infestation covering the most of two city
blocks was found in Memphis, Tenn. The ant numbers could not
have increased to any appreciable extent during the rather long
and cold winter of 1914-15, and yet in the early part of the following
June the infestation was found to involve nearly the whole of five
blocks. In October, 1915, it developed that the boundaries had not
been extended, though the ant numbers had greatly increased. The
food supply must have increased as fast as did the numbers of ants.

In several instances frequent observations made at points on the
frontier of the infestation developed the fact that the normal ad-
vance will average from 300 to 400 feet a year. The abundance of
native ants has some influence on this advance, since the Argentine
ant will not tolerate any of the native species, and in sos sence a
continuous fight is waged all along the frontier.

Heavy, flooding rains are undoubtedly a factor in the natural dis-
tribution of this ant, and in the vast region drained by the Mississippi
River and its tributaries it will be remembered that there are at least
two dangerous flood seasons and sometimes more, which contribute to
and accelerate the distribution of this species. Lumber, rotting trees,
uprooted shrubs, cane growth, fruit, vegetables, and all manner of
refuse contribute to the mass of matter borne on the crest of flood
water, and in this the ants seek refuge and are involuntarily trans-
ported. Nature has endowed this species with a remarkable habit of
self-preservation from drowning in times of floods, for when rising
water floods their nests and no other means of escape are presented
they cluster together and form a compact ball. The immature stages
form the center of this ball, with the queens and workers as the outer
portion. As the ball enlarges from the addition of other workers
which had been struggling alone in the water it gradually revolves.
It is kept revolving slowly by the outside workers continually striv-
ing to reach the top of the ball, thus permitting air to reach the
interior. The writer has had only one opportunity of witnessing the
formation of a ball of this kind. After a 5-inch rainfall several
balls, none more than 2 inches in diameter, were observed. According
to reliable authorities, such balls have been observed on many oc-
casions, some of them from 6 to 8 inches in diameter. The ants in

4 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE, |

these balls disperse when they come into contact with a secure resting
place, such as a floating piece of timber or land, but they have been
seen to float around for hours on still water. Mr. Smith, at Daisy,
La., states that he destroyed a large number of these balls by pouring
some coal oil on the water. The balls quickly broke up when in con-
tact with the oil and the ants died in a very short time.

Driftwood is another important carrier of this pest. A fallen
decayed log is an ideal nesting place. Such a log will usually decay
from the underside upward, the upperside or top making a roof for
the nest, with the rotted wood below drawing and retaining ample
moisture, thus affording excellent material in which to make galleries.
Logs of this kind are hght and easily floated and are important
factors in spreading infestations. Especially is this the case in those
parts of the country where heavy, flooding rains occur. In this
manner practically all the land along the Mississippi River below
New Orleans has been infested.

However, it is to the vehicles of man that the greatest distribution
must be credited. The most important are steamboats and rail-
roads. Commodities are carried from infested territory to uninfested
places and ant colonies are often to be found in shipping boxes, feed-
ing on sugar and other grocery supplies. Practically every one of
nearly a hundred steamboats landing between New Orleans and
Baton Rouge is infested with the Argentine ant. Further, it seems
likely that this ant was carried by boat. from Charleston, S. C., to

Wilmington, N. C., as the ant is to be found around the wharves and

shipping in both places. So gross is the infestation in both these
cities that it is possible that the species may have been introduced
into Charleston many years ago on coffee ships, as it 1s supposed to
have been introduced into New Orleans, the slightly colder winters
holding it more in check.

When inspecting cities far removed from New Orleans it has been
found that in the great majority of instances the infestations start
immediately around the wholesale-grocery and commission-merchant
establishments. ‘This indicates that when carried long distances the
ants are more likely to be taken through in solid carload lots of mer-
chandise which are rushed to their destination than in smaller con-
signments. ‘This is especially the case with perishable goods such
as fruit and vegetables. Cars containing broken shipments are side-
tracked at the first town to which goods are consigned, and the ants
present are likely to leave.the car at the first or second stop, which
fact is verified in that nearly all the small towns for a distance of
150 miles from New Orleans are infested. A serious feature of the
infestation of inland cities such as Texarkana, Memphis, Atlanta,
and others, is that the ants, having become established in the whole-
sale district, are readily distributed to surrounding smaller towns

Nee,

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 5

which are tributary to these centers. A point where such a distribu-
tion has occurred is Summerville, a little town 24 miles north of
Charleston, S. C., which has become infested, presumably, from the
latter place.

In a complete colony in the spring of the year three distinct forms
of adults are to be found—queens, males (drones), and workers, the
workers greatly outnumbering both the queens and the males. The
workers, foragers of the colony, are imperfect females with no re-
productive functions. The queens, which are the reproducing fe-
males, remain within the nest nearly all the time, and are fed and
tended by the workers. The males have apparently but one fune-
tion—that of fertilizing the queens. It will be readily understood
that, as in the social economy of ant communities of other species,
it is absolutely necessary that a fertilized queen be taken along with
a number of workers before a new colony can be started. It is quite
possible that almost every town and city in the Southern States has
had a number of workers introduced at one time or another, but
owing to the absence of a queen a noticeable infestation has not
become established. Workers alone carried in this manner would die
out. Such may be the case at Nashville, Tenn., where only a few
workers have been found. Later observations will be necessary to
decide this question.

ECONOMIC IMPORTANCE.

As a pest in cities the Argentine ant has no equal. Owing to its

small size and unobtrusive color, it is able to invade practically every
part of ordinary dwellings, stores, etc. It is almost omnivorous,
eating most cooked foods and a considerable percentage of the raw
foods that are to be found in the average pantry. It exhibits a
marked preference for some foods, such as sugar, sirup, honey, jams,
cakes, candies, pies, fruit, and meats of all kinds. The temperature
of refrigerators or ice boxes seems to have no deterrent effect, and
ants will readily invade them.
_ It is a common occurrence for Argentine ants to invade bed-
chambers, and while they do not possess a sting, they can cause
considerable pain with their mandibles. There have been many —
reports of babies being attacked by them in such numbers as to
cause serious results, and several of these reports have been verified. ©
In August, 1915, the writer located such a case in Augusta, Ga.
A reputable citizen of that city, residing in a heavy infestation of
the Argentine ants, gave the following account of such an attack on
his 4-weeks-old baby:

We were awakened in the night by a weak cry from the baby, and when

the light was turned on the baby’s face was black with ants. They were in the
baby’s nose, ears, and mouth. We hurriedly carried the baby to the bathtub

6 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE,

/

and started to wash off the ants. It took us nearly an hour and a half to get
the last ant off the baby. I feel sure that if we had not heard the ery, in a few
hours the child would have perished.

With conditions made almost intolerable in badly infested places,
it is not uncommon to find empty, unrentable houses. Realty values
accordingly drop.

The nurseryman ana truck grower are greatly molested by this
pest, owing to the ant’s fondness for the honeydew of aphids and
scale insects. The ants take the best possible care of these honey-
yielding species, and protect them from their natural enemies, fre-
quently building mud shelters over them, and as the host plants
grow, carry the young scales and aphids and place them on the
young tender growth, where they may more easily sap the juices
of the plants.
~ Newell and Barber? give a very graphic account of the manner
in which the Argentine ant has invaded the orange orchards of
Louisiana.

In corn, cotton, and sugar-cane fields the Argentine ant when
present is constantly attending the aphids and mealy bugs, increasing
the numbers of these species to an alarming degree, much to the
detriment of the plants. The writer has determined that a consider-
able loss of sugar results from the attendance of the Argentine ant
on the sugar-cane mealy bug.

HABITS.

Argentine ants are extremely social among their own kind, the
individuals never having been observed to quarrel with one another,
nor one colony with another. Workers may be carried for miles and
placed with others of their kind and no apparent demonstrations
of like or dislike are exhibited. The newcomers appear to enter
into the colony spirit and are soon lost to the view of an observer.
Any small nest will contain several queens which live together
amicably.

The summer nest may be located anywhere—under sidewalks,
under the sills of houses, in brick piles, stone piles, under a piece of
board or a piece of tin, in an old tin can—in fact, in any place con-
venient to the food supply. In the winter months there is a tendency
to concentrate into larger colonies, and they seek warm, dry, secure
nesting places in which to hibernate. These desirable places are not
plentiful, and where one is located the ants from some distance will
seek its shelter. The winter is the most hazardous period of the year,
for should a nest by any chance be flooded during a cold spell, when
the ants are dormant, the chances of survival of the colony would be
extremely slight. Usually throughout the latter part of December,

1 Op. cit., p. 24.

i

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. i

January, and February (at New Orleans) these large colonies are.
found. They sometimes reach very extensive proportions and may
contain several hundred queens and countless workers and immature
stages. These colonies are usually located at the base of large trees
en high, well-drained spots of ground, in manure piles, or in any other.
piles of decomposing rubbish where heat is generated. A warm day
will make them particularly active, and they will form trails in all
directions from these winter nests to food supplies. They may be
observed traversing the trunks of trees every warm winter day, and
from the trees trails are made to nearby houses, where ey cause
considerable annoyance.

With the advent of warm spring weather the breaking up of the
large colonies occurs. This is the time of the year that food is very
scarce, and at this season the ants are particularly aggressive and

troublesome in the houses. Z'his ts the best time to use poisoned sirup,
which will be described later, for controlling this pest.

LIFE HISTORY.

There are three adult forms to be found within a complete nest in
the spring months of the year—the queen, the male, and the worker.
A colony may be complete, however, with a queen and workers.
Three immature forms are also present—the egg, larva, and pupa.

EGG.

In an artificial formicary a fertilized queen lays from 3 to 30 eggs
per day when ample food is supplied. Itis very probable that under
natural conditions the egg production is considerably more. Only a
few seconds are occupied for the laying of each egg. A worker,
apparently awaiting the arrival of the egg, picks it up and transfers
it to a pile of eggs already in the nest. The surface of the egg is
somewhat mucilaginous and readily sticks to other eggs. This per-
mits the workers to handle the eggs en masse and also permits of
their being deposited in desirable locations on the walls and ceilings
of the galleries.

The ege when first laid is about 0.3 mm. long and 0.2 mm. wide.
It is elliptical, pearly white, lustrous, and without markings. As the
time for hatching approaches the luster disappears. It is extremely
difficult to detect the exact time of hatching. The average summer
incubation period is about 15 days, but this, of course, is subject to
the variations of temperature and humidity during this period.

LARVA.

The larva, when first hatched, is creamy white. Its body is very
curved, but it gradually straightens as the larval growth continues.
It is entirely helpless and is practically motionless.

8 BULLETIN 3877, U. 8. DEPARTMENT OF AGRICULTURE,

The workers feed and cleanse the larve, moving them about with
the fluctuations of temperature and humidity to the most desirable
places within the nest. The full-grown worker larva is about 1.5
mm. long by 0.65 mm. wide. The average larval period throughout
the summer months under normal conditions is about 13 days.

PUPA.

When the pupal stage is reached the sex of the individual is
readily distinguishable. The pupa is white, with the exception of
two distinct black eyespots on the sides of the head. The worker
pupa is about 2 mm. long, the head and thorax being the larger part
of it. The male pupa is about 50 per cent larger than the worker
pupa, and the queen is still larger. The two latter forms may be
readily distinguished from the worker pupa. The male pupa has
a very large thorax and a small, closely coupled abdomen, while the
queen pupa is much more symmetrical, the thorax is not so large,
and the abdomen much larger than that of the male. The pedicel
between the thorax and abdomen of the queen pupa is more con-
stricted and elongated than in the male pupa.

After the first few days the color of the pupa gradually changes
to creamy yellow and continues to darken until a light-brown color is
reached just previous to emergence.

The duration of the pupal stage of the worker throughout the
summer months averages about 13 days, while that of the male is
about 22 days. No records have been established of the duration of
the pupal period of the queen. |

The pupe of all the stages are aided in transformation by the work-
ers. Upon first emerging the adult is of a light-brown color which
gradually grows darker until the second day, when it becomes indis-
tinguishable from other adults.

DEVELOPMENTAL PERIOD.

By compounding the average periods of development of the egg,
larva, and pupa, a general average of 40 days results, which repre-
sents the complete development from egg to adult in the case of
the worker and a somewhat longer period for the males and queens.

ADULT FORMS.

The worker is about 2.5 mm. in length and of a dark-brown color,
and there is only one caste. The workers forage for food, attend the
queen and the young, and fight to protect the colony. A large per-
centage of the workers stay within the nest at all times and are
always ready for any emergency, whether it be to fight invaders or
to hurriedly seize the immature stages and retreat to securer locations
upon the slightest indications of rain or flood.

b.
{=

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 9

The workers are able to carry considerable liquid food in their
abdomens, which become distended and transparent. This food is
regurgitated when the nest is reached, and fed to the immature forms
and other workers and queens in the nest. They are quite long lived
and have been kept in artificial formicaries for many months at a
time. It is quite possible that they may live a year under natural
conditions.

The male is always winged. It is readily distinguished by its mas-
sive thorax, small head, and abdomen. It is about 3 mm. in length,
and the body color is of a dark brown, the same shade as the worker.
Males appear in the nest in the spring months of the year and
gradually lessen in numbers as the summer advances.

When the queen first emerges she is winged, but at the time of
copulation, or about that time, she loses her wings, and her activities
from that time are devoted to egg producing. The dedlated queen
is about 6 mm. long and of the same color as males and workers. It
is seldom that the queens leave the nest unless disturbed, but occa-
sionally they may be seen crawling along an ant trail in company
with the workers. At rare intervals they travel alone and may be
observed wandering about aimlessly.

The queens have frequently been kept within artificial formicaries
for more than a year, and it is reasonable to suppose that they will
live much longer.

NATURAL CONTROL.

It would appear that heavy rains and resulting flood are the only
factors of natural control of any great importance. They are espe-
cially effective if occurring during cold weather, for at this time the
ants are sluggish and unable to exert themselves. Moderately cold
weather does not appear to check their activities.

- On November 18, 1911, a heavy infestation of this ant was discov-
ered at Kosciusko, Miss., about half the town being infested. Resi-
dents stated that they had been troubled for about 7 years; several
of them, owing to the great annoyance, had moved to parts of the
town which were not then infested. On revisiting Kosciusko in
April, 1912, the infestation had decreased to such an extent that it?
was quite difficult to find any of the ants. The meteorological |
records of the winter months revealed the following striking facts: ©
The mean average temperature of the 6 months from November to
April, inclusive, was 49.5°, but the rainfall for this period was exces-
sive, reaching the total of 41.1 inches, whereas the average 10 years’
precipitation for these months had been only 27 inches. This con-
trol was, however, only temporary. In June, 1915, Kosciusko was
again visited and the ants were found to be very numerous and
causing great annoyance to residents. The infestation had spread

41860°—Bull. 8377--16——2

10 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE,

over practically the whole town, as well as near-by corn and cotton
fields.

During the same winter (1911-12) similar conditions were expe-
rienced at New Orleans, the winter months being accompanied by a
rainfall of 41.56 inches, as compared to the 10-year average of but
26.1 inches. The numbers of ants were greatly reduced, the mortality
probably being at least 70 per cent. The ability of this species to
overcome such a catastrophe was well illustrated, for by September,
1912, the ants had apparently reached their maximum numbers.

REPRESSION.
OUTDOOR BARRIERS.

A number of experiments have been conducted to discover, if
possible, an efficient outdoor barrier.

The sticky substance which is used in coating flypaper and is also
sold in bulk for banding trees was effective for only a few days. The
ants would carry particles of dirt and build a bridge over it. This
substance, made much thinner than usual, as suggested by Mr. D. M.
Rogers for use in the gipsy-moth work, was tried and with more
successful results. Heavy bands 4 inches wide spread on two mag-
nolia trees were effective for two months in the summer without
having to be replenished or combed.

In the cooler parts of the year these bands require frequent atten-
tion on account of the growth of mold on the surface. During wet
weather in the winter in Louisiana this mold will form in a very
few days, and the efficiency of the sticky band will be entirely
destroyed.

It was found that 5 per cent of a carbolized oil added to the thinner
preparation increased the effectiveness of the bands considerably
and entirely prevented the growth of mold. The bands were also
rendered more repellent and more resistant to winter conditions. <A
thin crust forms over the surface of the bands in the winter, but this
is readily combed into the band in the spring and the band is as
effective as ever. The crust on bands of the thinner preparation |
‘without the carbolized oil becomes too hard during the winter, and
it 1s necessary to use fresh material in the spring. These bands
were used on fig, magnolia, pecan, and orange trees and no injury to
the trees was apparent. There is a possibility that the substance
may be harmful to trees with a more tender bark, however.

To the thinner preparation were added in different tests 1 per
cent of bichlorid of mercury, 2 per cent of nicotine sulphate, 10 per

1 A wooden comb is supplied by the manufacturers for the purpose of combing the bands
when a coating of dirt, insects, or any other foreign matter collects on the band. This

foreign material is mixed in with a clean sticky substance, immediately under the surface
of the band, and the band is as efficient as ever.

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 11

)

cent of naphthalene, and several other repellents. While bands con-.
taining bichlorid of mercury and nicotine sulphate were effective
_ for slightly longer periods than the sticky substance alone, their use
is hardly to be recommended.

INDOOR BARRIERS.

Perhaps the most effective and durable barrier which can be used
indoors is a bichlorid-of-mercury tape or band. Tape is soaked in a
saturated solution of bichlorid of mercury and then hung up to dry.
It is then placed around the legs of tables, safes, etc., and if it is kept
dry will last from six months to a year. Common lampwick one-half
an inch wide is ideal for this purpose. After it has been treated in a
saturated solution of bichlorid of mercury and dried, pieces are
wrapped around the leg of the piece of furniture to be isolated and
ends lapped over tightly and pinned. The tape can be readily re-
newed by another soaking in bichlorid of mercury and repinned in
place. |

Twenty-five per cent of bichlorid of mercury mixed in shellac may
be paintéd around the legs of furniture, and when dry it will be quite
-as satisfactory as the tape.

Eatreme caution is advised in handling bichlorid of mercury, as
there is always an element of danger in using this poison. In recent
years the sale of this drug to the layman has been practically tee
continued.

A simple and efficient, though perhaps unsightly, barrier may be
made by placing the legs of furniture in saucers and putting a gen-
erous supply of moth balls in each saucer. The moth balls will
slowly volatilize, and it is necessary to add more from time to time,
but the ants will not cross the barrier thus formed.

Coal oil placed in saucers in which the legs of furniture rest will
repel the ant, but the odor of the oil is disagreeable to most persons.

: ANT POISONS.

Many and varied experiments have proved that it is futile to try
to exterminate Argentine ants with a poison which kills rapidly. A

, few workers may be killed, but the masses of ants will quickly recog- _
~ nize the source of fatality hd avoid the * doctored” food. The few
workers killed in this way will have no effect in reducing the numbers. ©
None of this poison will reach the queens in the nest, and it has been ©
found that it is essential to kill off the queens in order to prevent -
further multiplication of the pest.

Soon after the writer took up the work on the Racontane ant Mr.
LL. J. Nickels? published an article on the control of the Argentine
ant in California, in which a rather successful poisoned sirup was
described. It was decided to give this poisoned sirup a thorough trial

1 Nickels, L. J. Field Work in the Control of the Argentine Ant. Jour. Econ. Ent.,
y. 4, no. 4, pp. 353-358. 1911.

-

£2 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE,

in the Southern States. The following eapEEnnen is based on Mr.
Nickels’s recommendations:

EXPERIMENT AT HATTIESBURG, MISS.

At Hattiesburg, Miss., an infestation of 8 blocks was found to be
an ideal place for this PR i sa

The following buildings were located within the infestation:
Thirty-eight residences, 7 stores, 2 meat markets, 2 small hotels, 2
restaurants, 2 bottling neilt lisinnens (which will be designated here-
after as establishment A and establishment B), a laundry, a marble
factory, a sawmill and office, and a church.

Thirty dozen 1-pint fruit jars were prepared in the manner out-
lined by Mr. Nickels. The porcelain was broken out of the metal
tops and five holes about three-eighths inch in diameter were punched
near the center of each top. Sponges were cut up into pieces and a
piece inserted in each jar. The piece of sponge filled about a third of
the space in the jar.

A gill of the poisoned sirup was put into each jar. On each jar
was pasted a poison label.

On September 28, 25 dozen of these jars were distributed—about
six Jars placed in each house and store. Two vacant blocks were
not covered at this time, but on November 16, 3 dozen jars were dis-
tributed on these blocks. As the j jars had to Be placed outdoors, they
were laid on one side to prevent rain from entering. The residents
of the other blocks were questioned as to results, and they reported
very favorably. In most cases the ants had become much less abun-
dant. The two meat markets had fewer ants than before, but the
sirup rooms of both bottling establishments were as badly infested as
ever, the ants evidently preferring the flavored sirups to the poisoned
sirup. >

In the latter part of April, 1912, the infestation was again deter-
mined. This was immediately after the winter previously referred ta,
when the infestation had been so reduced at Kosciusko and New
Orleans. Though the numbers of ants had certainly been reduced in
Hattiesburg, they were still present in proportionately greater num-
bers than in New Orleans. It is likely that the better wintering
facilities at Hattiesburg were due particularly to excellent drainage
and the presence of numerous trees.

On June 18 another inspection was made. The numbers of ants
were at this'time about 60 per cent of what they were during the
previous November. The eastern line of infestation had not been
extended and the ants were giving little trouble in the houses, though
they had apparently concentrated around the sirup rooms of both
bottling establishments. The stores and meat markets had not been
troubled to any extent, but there were many trails of ants on the
trees. Many of the jars were examined, and it was found that a de-

de in a ES i a i

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 13

composition had taken place in the sirup in the jars, a very disagree-
able odor being given off. As many of the jars as could be found were
collected. These were thoroughly cleaned, especially the sponges,
which were washed in boiling water. Fresh sirup was prepared and
the jars recharged and again distributed.

The jars were again recharged in October. At this time, though
the infestation had not spread, the ants were more numerous. They
were very numerous in the sirup rooms of both bottling establish-
ments, and in both meat markets.

Observations were made in December, and at this time conditions
were fairly satisfactory. Ants had troubled only two of the houses,
in each instance only for a day or so, and had then left. The bottling
establishments were closed for the winter. The intention was to
recharge the jars at this time, but the status was so satisfactory that
it was decided to leave them until the following spring.

In the beginning of April the ants were not very plentiful. Only
three houses had been invaded during the winter. The sirup rooms
of both bottling works were again besieged.

By the latter part of May the ants were more numerous all over
the infested area, though none of the residents or storekeepers had
so far been troubled. The proprietor of bottling establishment A
now had his sirups isolated and the ants were noticeably fewer
around this building, but they were in increased numbers around the
other plant. The ants were now very numerous on one block, and as
the jars had not been satisfactory outdoors, special paraffin-covered
rainproof paper bags were prepared to place on the trees near the
houses and along the streets throughout the infested area. The

“experiment had been conducted for 20 months and the results had

not been entirely satisfactory. The ants had been almost completely
kept out of the houses and stores, except the sirup rooms of the
bottling works, but large numbers were still present outdoors.

It is fairly conclusive that the sirup within the houses repelled the
ants, for even in the spring the ants gave little trouble to the resi-
dents.

On July 9, 50 paper bags’ containing this sirup were placed on
trees throughout the infested area. About half of these bags were
placed on trees in one block. All the bags were tacked about 15 feet

_ above the ground to keep them out of reach of children and to arrest.

evaporation as much as possible, bags at this height being in the
shade.

On August 13 a status inspection was made, and very remarkable
results were observed. There were not at this time more than 20
per cent of the ants on the trees as compared with July, and all of
the houses without exception situated anywhere near the trees had

1A description of the preparation of this bag is given on pages 20 and 21.

14 BULLETIN 877, U. S. DEPARTMENT OF AGRICULTURE.

been invaded. None of the stores along Bay Street, near which were
no trees, had been bothered by the ants. All the jars were recharged.

In November conditions were very satisfactory. Comparatively
few ants were to be seen, and these were mostly on the trees. No
ants were to be found in the sirup room of bottling establishment A,
and there were very few in the vicinity of the building. There were
very few ants on the trees in one block. By far the largest number
of ants were to be found around the building in which bottling estab-
lishment B had been located. People in the house next to this build-
ing were being considerably troubled.

In January, 1914, all the jars were recharged and 150 paper bags
containing the poisoned sirup were distributed over the infested area.

On April 7 a thorough inspection was made, and the numbers of
ants were found to be greatly reduced. Nowhere had the ants caused
any annoyance. There were very few ants on any of the trees. In
several places native ants had again taken up their abode within the
infested area, indicating that the Argentine species was dying out.

In the latter part of May the jars were recharged and 300 poison
bags placed in suitable locations. An inspection at that date proved
that the experiment was continuing very satisfactorily.

Native ant nests could be found dotted over the whole area. The
largest number of Argentine ants was found around the abandoned
building of bottling establishment B; in fact, this was the only place
where the ant could be found in large numbers.

An inspection on June 29 indicated that the experiment was pro-
gressing favorably. The numbers of Argentine ants around bot-
tling establishment B had greatly decreased, it being actually diffi-
cult to find them on these premises. Not a vestige of the infestation
could be found on three of the blocks.

In mid-September the territory was again inspected. The condi-
tions were found to be excellent. Scarcely an Argentine ant could
be seen in any part of the once-infested territory.

Everyone living in the formerly infested area was of the opinion
that the Ae ccntine ants had been completely eradicated, but the
writer found a few workers. However, he decided to concen the
experiment concluded, for the time at least. It was possible that
the queens were all destroyed and that just a few workers remained.
There was also the possibility of the native ants finally exterminating
the Argentine species.

The poisoned sirup had finally proved efficient, though it must be
stated that it was necessary to expose it both indoors and out.

IMPROVEMENT OF THE NICKELS SIRUP.

In the tests with the Nickels sirup a number of objectionable
features were encountered which finally led to the preparation of a

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. -15

greatly modified sirup. In all the experiments the sirup proved very
attractive and palatable to the ants at first, but their visits gradually
decreased until the sirup was avoided, although in some instances the
trails continued to pass by the poison jars. The period of attendance
at the sirup varied somewhat with the seasons, being longer in winter.
Even in the winter, however, a repellent action was apparent. In
preparing the solution it had been noticed that the sirup turned
brown, becoming darker the longer it was boiled, although it was
made in a pail which in turn was placed in a bath to prevent burning.

Another objection was the crystallization of the sirup to a greater
or less extent upon cooling. On the advice of a sugar chemist the
proportion of water was increased to make a saturated sugar solu-
tion ; 10 pounds of water to 20 pounds of sugar and 1 ounce of sodium
arsenite were used. The Nickels sirup contained one-fourth per cent
arsenic, while this more dilute sirup contained one-fifth per cent,
but the dilute sirup was quite effective. With the exception of the
first application, the dilute sirup was used throughout the length
of the Hattiesburg experiment. Crystallization of from 5 to 15
per cent of the weight of sirup still occurred in short periods, but
as high as 50 per cent when the sirup had been in the jars for several
months. This of course had the effect of proportionally increasing
the percentage of poison in the liquid and consequently its repellent
power. Newly made sirup appeared to be less repellent than that
which had stood for several weeks.

The repellent action of the sirup is illustrated by an experiment
conducted in a private residence, which was badly overrun with ants.
The ants were abundant in the refrigerator, safe, and sink, and literally
covered the floors. Six fruit jars containing the Nickels sirup and
sponges were placed in different rooms in the house, and 6 paraffined
paper bags containing the same sirup and a sponge were placed
around the house outdoors on trees, fence, and back porch. ‘The
sirup was about a month old. The experiment was begun at 1 p. m.
At 5 p.m. hardly an ant was to be seen in the house, although a few
were to be found at each jar and many were visiting the bags. Two
days later not an ant could be found in the house and only three of
the bags were attended by ants. As it seemed impossible that the
colonies could have been exterminated so quickly, the adjacent vacant |
lot was inspected. This lot was overgrown with weeds, and in a
corner near the house there was a pile of old lumber. Ants were
found in abundance nesting in the lumber, and many were present
wherever they could find dry quarters in the lot. It was quite evident
that the ants had been repelled by the poison.

A series of experiments to obtain definite data on the repellent
properties of the sirup were conducted in the Horticultural Hall,

16 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE,

Audubon Park, New Orleans, with the Nickels sirup in the strength
as recommended originally, and also double, half, and quarter
strengths. One gill of sirup was used to a jar, each jar being
placed on its side to give free access to the ants, to prevent the
entrance of water, and to prevent mold. The “ Hall” furnished
ideal conditions for the experiment, the temperature throughout the
year being kept high and uniform. The abundance of various
species of scale insects and aphids attracted the ants in great num-
bers at all seasons, but especially in cold and wet weather. Three
jars of each strength were used and observations were made fre-
quently for a period of 32 days. At the time of this experiment
the ants were very numerous, due to the extremely wet summer of
1912. The rate of attendance and relative repellent value of the
four strengths of the poison are shown graphically in the first part of
Table I.

TaB_E I.—LHeperiments with sodium arsenite (NaAsO,) added (in four strengths?) _

to sugar sirup solution, 1912.

[Symbols: A= Heavily visited by ants. B=Only attended by afew ants. C=Not attended by ants.]

FIRST TEST, IN HORTICULTURAL HALL.

Double strength. | Nickels solution. Half strength. Quarter strength

BOT AS UR OUR At I SRA AT Ori Sa ened | enna an
Ay OB le ABB OL Ae AeA ares RT AUS ATs ATS ara ana eat
Be SBS Be Ba I A igs PS Yate |e aN
yea Pitas ews beens aa fae a Pei Fe Wao (Re Neeclie Ween ge PN Ij oe
Boh. CB Bel ea i Are SAE tle pe NS eed ace
13 QU Orne ee Want| Wan) at WO ieee ae Gee eee UI Ve ge hoy
T3h| each ae (oar | ie ane EO eee (are. e Ws coNE\. |p on.
OMe Vane Us al C8 Pl ne Wes Wa PRU genre) en Gate hos
Be. Bea AAS APE a Eg STS Sa 09 Bt a haat
TSI A Oe nee Cate aaa Wa Ce) (ape ence) ceed ele ie Sf s
Ae!) SB Beal 6 Fes al a ie er lene eee
Cola Mew OG es! WE) bai Gitte Wan ibn sien! SMO Wan Gly UU Woot Lips
Be AC Be Tay, ie A a el Gale RR ee a ae

Bebe Ce GAO ai As VAD oN hn calle ve ee

Te Olam (ELC laal ACG) Ea (a) Nabi (Wass easy PIS tak cctlth her <8 o

COHn mK Glen cM Mm Ot Wed God We Canoes Celle! Mrgheler A | TA,

GM ENE Ge be Age Ads I BN ERT eee cas al

DUPLICATE EXPERIMENT, USING PAPER-BAG SIRUP CONTAINERS TACKED ON FIG
TREES (OUTDOORS).

Dniliyg 26M eerie 5 eae ee ciec A A C A A B A A A A C A
ly posuere mene ves B B C B B B A A B A A A
ARG 29s ree lee apt tainlaie iatesnieiatn A | A B B A A A A A A A A
Afni CUE eee at aear een ipie. A B C C A A A A B A A A
ADU Rea as Ai ES eae C B C B A B A A A A A A
PAUISTISIAbe sachs oe Lone kee C A C B B A A A A A A A
AI SUSHI Se eet ace nae Cc C C ¢ B A A A A A A A
NIT CUISH OFA ee or tease sae ee B Cc C A A A A A A A A A
PAITORISTO seers eine ne ewe icter. A A Cc A B B A B A A A A
TRUSTS EO is sa ae i A A C A A A A A A A B A
MISUSE ee alc 3 B B C A A A A A A A A A
VIC TISE MG aE ae ake Meee B Cc A A A B A A A A A A
EANIOUIS GPO serves ees hentai ee B B ¢€ A B B A A A A IX A
IN CG TTS BPA Ney eR ee a (e Cc B B A Cc A A B A A A
ATTA D IRCA ete ase aa erese B C © A A B A B A A B A
INS TVG US 7G a lic eh a A © B A A A A B A A A A
IAL OMS UO Bee cacao aaa A B CG A B Cc A A B A A A
PA USUI Ol eise ee elise scenic A A C A B B A B A A A A
Lpouble strength= {222 "224 10 pounds granulated sugar + 5 pounds H,0+ 1 ounce NaAsOnz.
Nickels solution______-___ 10 pounds grarulated sugar +5 pounds He0+ 4 ounce NaAsOs.
Eraittstreno bhi ss ioe Sos OL 10 pounds granulated sugar +5 pounds H.O0+ 4 ounce NaAsOs.

Quarter strength___.______ 10 pounds granulated sugar +5 pounds H20+ 4 ounce NaAsOs.

Ae

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 17

_ The experiment was duplicated, except that the sirups were placed
in waxed paper bags tacked on fig trees. These bags each held a
gill of sirup, and sponges were placed in the sirup to allow easy
access of the ants. At the time of conducting the experiment the
figs were ripening and the ants were visiting the trees in immense
numbers. It will be seen from the second part of Table I that the
results were substantially the same as in the indoor experiments.
The two experiments may be summarized as follows: :

The most concentrated sirup (2 ounces sodium arsenite) at-
tracted great numbers of ants in only 382 counts, few ants in 34
counts, and no ants whatever in 39 counts.

The standard Nickels sirup (1 ounce sodium arsenite) attracted
great numbers in 62 counts, few ants in 25 counts, and no ants in
18 counts.

The half-strength solution (4 ounce sodium arsenite) attracted
great numbers in 88 counts, few ants in 12 counts, and no ants in 5
counts. j

The quarter-strength solution (4 ounce sodium arsenite) attracted
great numbers in 92 counts, few ants in 4 counts, and no ants in 9
counts.

The experiments prove, therefore, that the excessive quantities of
the arsenic in a sirup will cause it to become repellent. The observa-
tions also indicate that the sirup decomposed more rapidly as the
amount of the sodium arsenite increased.

Dr. W. E. Cross, research chemist of the sugar experiment station
at Audubon Park, was consulted with regard to the various defects
in the Nickels sirup. His explanations and suggestions, which were
of great importance in the further conduct of the investigations, are
given below.

When granulated sugar (or sucrose) is heated, it is partially
changed to invert sugar (or glucose), and if to this is added sodium
arsenite, which has an alkaline reaction, chemical decomposition
takes places When heated this reaction is hastened and the com-
pound becomes darker and darker. On account of the instability of
the sirup, it will further decompose on standing and the final prod-
uct will be a substance with an unpleasant odor and taste. The .
addition of a small quantity of tartaric acid to the sugar sirup.
before adding the sodium arsenite will produce a greater inversion
of the sucrose, thus lessening the danger of crystallization, and will
neutralize the alkalinity of the sodium arsenite, preventing decom-
position. If a slight acid reaction is obtained the sirup will keep
indefinitely. The inversion of the sucrose reduces the sweetness of
the sirup, and to balance this 7 per cent of pure honey is added.

18 BULLETIN 3877, U. S. DEPARTMENT OF AGRICULTURE.

The preparation finally proposed by Dr. Cross is made as follows:

Prepare a sirup:

Granulatedyoucar 962 a4 see see ae Es Pee ee pounds__ 15
AWW a ber ses ate Ry dee ee ee SIE area pints2--447)
Partinic acid: (crystallized. 22 22s 2 Nee ea ee _ounce_- 4
Boil for 30 minutes. Allow to cool.

Pussoive, sodium arsenite: (CO: be) ee ee eee ounce. #32
Tn HOE Water 22 Se feel) Bee Te ae ae ae eee pint st

Cool. Add poison solution to sirup and stir well. Add to the
poisoned sirup:

ET Ta Gy Sg a ee a ee pounds__ 1

Mix thoroughly.

Nie

& :

On April 23, 1914, Dr. Cross and the writer prepared two sirups of
the above formula (exclusive of the honey, which only makes the
sirup more palatable), except that one lacked the tartaric acid. After
cooling, they were tested in a refractometer, with the following
results:

Sirup with tartaric acid, specific gravity 1.339, Brix (sugar content) 68.8.
Sirup without tartartic acid (Nickels sirup), specific gravity 1.343, Brix 68.95.

The Nickels sirup had lost 0.75 per cent of its sugar content and
was of a very dark brown color. The new sirup was bright yellow
(amber color), clear, and transparent. Equal samples of each were
placed in quart exhibit jars with ground-glass stoppers, labeled, and
set aside. A second reading was made on June 20, 1914, as follows:
Sirup with tartaric acid, specific gravity 1.340, Brix 68.40.

Nickels sirup, specific gravity 1.3321, Brix 67.01.

The new sirup had lost 0.4 per cent of its total solids and had not
noticeably changed in color or sweetness. The Nickels sirup had lost
1.04 per cent of its total solids, was nearly black, partly crystallized,
and had lost much of its sweetness. In the beginning of August the
stoppers were removed and cheesecloth tied over the mouths of both
jars, to find how evaporation would affect these sirups. The jars
were placed on a shelf in the laboratory. In the beginning of
January, five months after the jars were first left open, they were
examined. Figure 2 shows the conditions. The difference in the
quantity of the sirups, in color, and in the crystallization that had
taken place within the jar containing the Nickels sirup may readily
be noted. A reading was taken of these sirups, as follows:

Sirup with tartaric acid, specific gravity 1.385, Brix 75.48.
Nickels sirup, 1.367, Brix 72.68.

1In the first experiments one-half ounce of tartaric acid was used, but this is found
unnecessary.

2In earlier experiments the sirup was boiled 30 minutes after addition of the poison,
but boiling will raise the ** Brix’ (total solids), which is to the disadvantage of the sirup
as an ant bait.

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 19

The Nickels sirup! was then drained from its jar and was found
to weigh 160 grams. The jar and crystals were then weighed, the
crystals dissolved out of the jar, and the weight of the jar subtracted
from the total weight. of the jar and crystals. It was found that 333
grams of sugar crystals were present. .

Grams,

Weicht ob sirup, when first made. 22)ue) 3 ea hue GEO 23
Weight of sirup remaining > SUSE CLyStals 12 Was ie Cea ab Ate 493. 00
Water passed off by evaporation. _______-- _-+_-~_____-_ 167. 23

The 660.23 grams of sirup contained 1.333 grams of sodium arsenite with a

poison content of 0.202 per cent.
The 160 grams of sirup remaining contained 1.333 grams of sodium arsenite.
The poison content was now 0.836 per cent.

The sirup with tartaric acid had a small precipitation. As the
Brix had been raised 7.4 per cent through evaporation, the poison
content was very slightly
raised. This sirup now
weighed 648.35 grams, the
color and sweetness being still
quite stable.

Immediately after prepar-
ing these two sirups, April
23, 1914, 2 fruit jars of each,
containing 1} gills of sirup.
apiece (without honey), were
set out along heavy ant trails
in the Horticultural Hall.
Absolutely clean and odorless
sponges were used.

For the first 4 days the ants
showed a preference for the
old type of sirup (without
the tartaric acid) but for the

Fie. 2.—Comparison of the improved sirup (right)
next 21 days they showed no with the Nickels sirup (left), showing the amount
preference. Then one jar of of sirup left a each and the amount of sugar in

5 the Nickels sirup. (Original.)

the old sirup was abandoned.
This proved to be partially decomposed. On moving to another spot
it was attended for 10 days more, then abandoned completely. Thus
for a total of 35 days this jar attracted the ants. Seven days later
the other jar of this sirup was abandoned and no matter where placed
neither jar had any attraction for the ants.

Nu

UUVVQVUUDETU ET EAVES

bee LUT TEA TT

|

1 Figure 3 shows the small quantity of sirup that still remained, as well as the large
bulk of Sugar crystals which had formed in the jar. The jar containing the acidified
sirup is placed at the side for comparison.

¢

20 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE.

The jars with the new type of sirup were visited constantly for
62 days, or to the conclusion of the experiment. The small amount
of sirup left was still clean and as sweet as at first.

Tests of the poisonous qualities of both liquids were made with
colonies in Janet cages, under control as to food. There was prac-
. tically no difference in toxicity. Workers in
both cages began to die in 4 days, the queens
stopped ovipositing in 14 days, and winged
males died very quickly, the queens in 17 days,
and the whole colony in each case was extermi-
nated on the thirty-second day.

PRACTICAL TESTS OF THE IMPROVED SIRUP.

The new sirup, made exactly as in the for-
mula given above, is very palatable to the ants
at any season of the year. It was found that
containers charged with it placed at selected
points outside a residence would attract the
ants and they would cease to invade the house.
A private residence in a large plot of ground
on a street corner with a row of large oak trees
along each street was heavily infested with
ta ants, which were to be found in the sink, the
Fic. 3.—Comparison of the Tetrigerator, all over the floors, etc. On June

improved sirup (left) 18, 6 cans each containing this sirup and

ee ee sponge were hung on the brick pillars which
evaporation. The im- supported.the house. The following morning
proved sirup is sti there was scarcely an ant to be seen in the

clear and sweet, while ‘ :

the Nickels sirup is house and the ants were attending the sirup

dark and full of erys- .- Ene ¢

tals and decayed mat. INlargenumbers. The same-conditions existed

ter. (Originak) throughout the length of the experiment, which
was terminated on August 10. Many such small experiments have

been conducted, the results being equally successful.

APPLICATION OF THE SIRUP.

The paraflin-covered paper bag? shown in figure 4 is undoubtedly the
cheapest container. It can be made in large quantities at a cost of about
$5 per thousand. Small 1-pound bags used in grocery stores are ob-
tained, and two or three holes about one-fourth inch in diameter are cut
through each folded bag with a leather-punch or similar instrument.
This provides each bag with two holes on each side for the entrance
of the ants. Being opened, the bags are dipped in a pan of molten

1 The writer is indebted to Mr. R. W. Moreland, Bureau of Entomology, for his sugges-
tions in the preparation of this ae container.

f
:
7
:
‘

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. Dik

paraffin and set aside todry. The paraflin, forming a waterproof sur-.
face, materially lengthens the life of the bag, which is protected from

the entrance of water through the holes
by part of another (2-pound) paraflined
bag which covers the first one like a can-
opy. Inuse,each bag is provided witha
small quantity of poisoned sirup and a
piece of sponge, the protecting outer
piece of bag is drawn up over it, and
the ends of both are folded over at the
top and tacked to a tree. On account
of the bag coming together at the top
it ig very narrow at the point where
the entrance holes are made; conse-
quently very small pieces of sponge are
required. The bags have been known
to last for long periods, but the larger MY,
percentage of them last only about 2 or LS MLA

8 months. They can not be recharged. ric. 4.—Paraffined paper bags ar-

The tin can ranged as a container for ant

: poison sirup. The apron has been

shown in figure cut away to show the ant en-

wins, us trance holes. Such bags are nailed
5 is the most

to trees, (Original.)

satisfactory
container. Any sized can may be used, but
the handiest size is the one-half pound bak-
ing-powder can. The can must have a fric-
tion cover, and of course it must hold water.
If the can is indented deeply on the two op-
posite sides (as illustrated in the drawing,
fig. 5) and the cover replaced, it will be ob-
servable that there is ample space between
the top of the can and the cover for the en-
trance of the ants, and the can, if kept in an
upright position, will be weatherproof.
About a gill of the sirup will be sufficient for
several months, but in heavy infestations it is
better to put 2 gills in each can. It is very
advisable to place a fairly large piece of

for ant-poison sirups used SPONnge in the can. The sponge will float on

in outdoor experiments. the sirup and allow the ants to feed in large

oe numbers. A piece of wire about 6 inches
long may be bent for a handle, a hook inward at each end being made.
‘The hooks may be attached under the lid of the can where it projects
over the part that has been indented. This forms a handle by which

SN
IY ‘
ANN \ °
EIN ONAN EN ‘
S

AN

G4
Tn5
Y
Z
ZG

Vy
My
YY 4

/

Fie. 5.—Tin can container

ae

22 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE.

the cans may be hung on trees, fences, walls of houses, etc. The ants
prefer to climb for their food, and it is well to hang the cans near ant
trails going up trees, walls, etc. It is advisable to hang the cans in
the shade to prevent the evaporation of the sirup, for though it has
been proved that evaporation does not affect this sirup to a marked
extent, it is well to avoid raising the.solid contents of the liquid.
Eight to ten of these cans should be sufficient to place around an
ordinary city house and lot. If the grounds are large and if as,
trees are present, more cans should be placed out.

From the results so far obtained, the careful preparation of the
poisoned sirup can not be too highly emphasized. Very accurate
balances are necessary for the weighing out of the poison and the
tartaric acid. ‘This is especially true when small quantities of the
sirup are prepared.

PLANS FOR MUNICIPAL CONTROL WORK.

In effecting control in towns and cities it is first necessary to ascer-
tain the extent of the infestation. This should be mapped out so that
workmen in distributing the cans will be able to refer to the map to
insure the covering of the entire territory. Cans may be obtained at
wholesale at about $16 per thousand. About 10 pounds of “ grass”
sponges will be required per 1,000 cans. These will cost about 75
cents per pound. Thesponges should be thoroughly washed and dried
before use. When wet they may easily be torn into pieces about
2 by 2 inches. Using 1 gill of sirup per can, 200 pounds of granu-
lated sugar will be required per 1,000 cans. The cost of the sodium
arsenite is about 80 cents per pound, and 1 pound will be sufficient
for 1,500 cans. Tartaric acid (crystallized) costs about 70 cents a
pound, which will be enough for 4,500 cans. From 60 to 100 cans
will be required per block, depending on the size of the block. The
late fall, winter, and spring are the most desirable times in which to
do this work, as in these seasons the natural food is least plentiful
and the ants most hungry. Two men should be able to prepare the
sirup, wash and tear up the sponges, and charge about 2,000 cans per
day and distribute about 1,000 cans per day.

TRAPPING ANTS.

By taking advantage of their winter colonizing habit the ants may
be attracted in large numbers to specially prepared trap boxes, which
may be fumigated when large numbers have gathered in these boxes
for winter nesting. Newell and Barber, who originated this method
of control, describe in Bureau of Entomology Bulletin 122 some very
interesting and successful trap-box experiments. The boxes were
filled with decaying vegetation, the heat generated making them very
attractive as hibernating quarters. Carbon bisulphid was found to

> oe

—_— . ivy “~_ SS, ee ot) ee. as ee Daly 4 ox — Parla ltr ad \_ ert Pe

THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 23

be the best and most economical fumigant for use in the trap boxes.
Tt is hardly necessary to state that this method of control is not ap-
plicable to city conditions, where dry nesting quarters are very
plentiful and the ants do not colonize to any great extent.

SUMMARY OF CONTROL MEASURES.

ANT BARRIERS.

In grossly infested houses much relief may be secured by isolating
tables, refrigerators, safes, beds, etc., with bichlorid-of-mercury tape,
or by placing the legs of articles of furniture in saucers filled with
moth balls or coal oil. Trees, beehive stands, and other outdoor ob-
jects may be isolated with the sticky substance used on fly paper but
made thinner than usual. If 5 per cent of carbolized oil be added,
the durability of the bands will be considerably increased.

REPELLENT ANT POISONS.

Repellents are much used to keep the ants from buildings. Strong
antimony or arsenical sirups, a number of which are sold by drug-
gists in infested territory, are used for this purpose. They give
quick relief for short periods, but they are not a factor in the reduc-
tion of the infestation.

ATTRACTIVE ANT POISONS.

The only effective poisons yet known for permanent control are
poisoned sirups. The improved arsenical sirup recommended on
page 18 will not spoil and is superior to any other formula yet tested
on account of its stability at high temperatures, freedom from crys-
tallization, and continued attractiveness.

TRAPPING ANTS.

Trapping ants may be accomplished in rural locations by provid-
ing boxes of decaying vegetation in the winter. The colonies will
move into these boxes and the ants may then be killed with carbon
bisulphid.

WASHINGTON : GOVERNMENT PRINTING OFFICE: 1916

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