W.L Brown, Ir,
CIRCULAR No. 387 MAY 1936
UNITED STATES DEPARTMENT OF AGRICULTURE
DISTRIBUTION OF THE ARGENTINE ANT IN THE
UNITED STATES AND SUGGESTIONS FOR ITS
CONTROL OR ERADICATION
By M. R. SMITH, associate entomologint, Bureau of Entomoloyy and Plant
How to recognize the Argentine ant 3
Habits and economic importance 3
Distribution and abundance 5
Means of spread 5
Response to ecological factors 7
General distribution in the United States.- 9
Occurrence and abundance in the infested
Control and eradication work in Mississippi--. 24
Surveying infested areas 25
Estimating the cost of a campaign 26
Supplies needed 26
Organizing and conducting a campaign 30
Control and eradication, etc. Continued
Best seasons for campaigns 32
Reaction of ants to the poison ^ 33
Determining the effectiveness of a cam-
Eradication work 34
Supplementary measures 34
Success of control and eradication work in
Method recommended for the control or eradi-
cation of the Argentine ant 36
Literature cited 38
Sometime previous to 1891 there entered the United States at
New Orleans, La., a South American' ant which was destined in less
than 50 years to spread over not only a large part of the Southern
States but a considerable area in California, as well as small areas
in several other widely removed States. Within these limits the
Argentine ant, Iridomyrmex huimlis (Mayr), as it is called, has
proved to be probably the most annoying of the economic ants and
a pest of no little importance. Although especially obnoxious to
housekeepers, hotel managers, and cafe owners, it also causes serious
losses to orchardists, planters, beekeepers, and others.
According to Newell (10) * Edward Foster, of New Orleans, was
the first person to observe this ant in the United Sta,tes. From
Foster's observations (3) it appears likely that the Argentine ant
1 The work described in this circular was under the general direction of S. A. Rohwer.
The scouting and the evaluation of the Mississippi method of control and eradication were
under the supervision of the author. The scouting was done by T. F. McGehee, L. C.
Murphree, H. T. Vanderford, and D. B. Read. The States scouted by these men were as
follows: Alabama, Mississippi, 'Arizona, New Mexico, Illinois (Murphree) ; Georgia, North
Carolina, Virginia, West Virginia (Vanderford) ; Louisiana, Oklahoma (McGehee) ;
Florida, South Carolina, Missouri, Arkansas (Read) ; Texas (Murphree, Vanderford, Reed,
and McGehee) ; Kentucky and Tennessee (Vanderford and Murphree). Information on
the status of the ant in California was furnished by Harry S. Smith, and in Maryland by
B. N. Cory. Officials in entomological, plant quarantine, and extension work in the
various States offered many helpful suggestions and aid. The data relative to the work
in Mississippi were supplied by Clay Lyle and R. P. Colmer, of the State Plant Board of
Mississippi. The photographs were made by Ross E 1 . Hutchins.
3 Italic numbers in parentheses refer to Literature Cited, p. 38.
41271 36 1
2 CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
was first carried to New Orleans in coffee ships from Brazil. These
ants were first found in California at Ontario in 1905 by E. S. G.
Titus. In 1907 they were discovered at Berkeley by J. C. Bradley,
and by 1910 C. W. Woodworth, of the University of California,
reported that 5,000 acres in that State were infested with this pest.
In 1915 Newell and Barber (11) listed 16 localities in California
as being infested. Since that time the ants have continued to spread
rapidly over new areas in the United States.
As this insect increased in economic importance, many investiga-
tions of its biology and control were undertaken. Newell and Bar-
ber (11) have published a comprehensive account of the ant's life
history and a description of its stages. Work by Horton (<, 9)
in the citrus groves of Louisiana and by Woglum and Borden (17)
in California deals with this ant in its relation to citrus, and the
means of combating it. The development of a satisfactory poison
bait by Barber (#) was the culmination of much work along this
line by Barber, K. S. Woglum, and A. D. Borden, working for the
Bureau of Entomology, United States Department of Agriculture,
and Nickels (12) , of the Department of Entomology of the Univer-
sity of California. Not only has this bait given satisfactory results
wherever it has been used in the South, but Ryan (13) has also in-
dicated its successful use in citrus groves in California. Mississippi
was the pioneer State in Argentine ant control and eradication
work, regular control campaigns having been organized there as
early as 1920.
The act making appropriations to the Bureau of Entomology for
the fiscal year 1931-32 provided funds for a further study of the
Argentine ant. The work outlined was divided into two parts: (1)
To determine the present distribution and relative abundance of
the Argentine ant in the United States, and to map the infested
areas as accurately as possible within a limited time and at a rea-
sonable expense; and (2) to study the methods used by the State
of Mississippi in controlling and eradicating the Argentine ant, and
appraise the effectiveness of suppression campaigns conducted by that
The survey to determine the distribution and abundance was begun
in the fall of 1931 and completed late in the spring of 1933. During
this time 4 men scouted for the ants in the principal towns and
cities in 18 States. No effort was made to scout rural areas because
of the great expense involved and the probability of finding only
a small number of infestations. The States scouted most thoroughly
were South Carolina, Florida, Georgia, Alabama, and Louisiana,
one or more localities in every county being examined for ants.
Scouting was also done in Oklahoma, North Carolina, Virginia, West
Virginia, Kentucky, Tennessee, Mississippi, Illinois, Missouri, Arkan-
sas, Texas, Arizona, and New Mexico. Since the status of the ant
in California and Mississippi was rather well known, no work was
done in California and only a few localities in Mississippi were
scouted. The data collected in connection with this survey, which
are summarized in this circular, are believed to be adequate for ap-
praising the Argentine-ant situation as it existed in the United States
at that time.
During the summer of 1933 the author and L. C. Murphree in-
spected certain areas in Mississippi believed to have been freed of
ARGENTINE ANT IN THE TJNITED STATES 3
Argentine ants as a result of campaigns directed by the State Plant
Board. The methods of inspection and those used in the control and
eradication work are described in this circular.
HOW TO RECOGNIZE THE ARGENTINE ANT
Argentine ants are easily confused with other species, and in the
course of the surveys native ants that resemble Argentine ants are
occasionally encountered. The Argentine ant (fig. 1) can be dis-
tinguished from these by the following characteristics : The worker
is about one-eighth inch long and of an almost uniformly brown
color. It is slender in
form and moves
rather quickly. The
worker possesses a
single joint (petiole)
between the thorax
and the gaster. When
several workers are
crushed, a character-
istic musty or greasy
odor (16) is given off.
Other native ants
either are odorless or
they have Spicy or FIGURE 1. Argentine ant worker. Greatly enlarged.
pungent odors, or a
somewhat sweetish, nauseating odor similar to that given off by Tap-
inoma ants. Some of the ants most closely resembling Argentine
ants have the last-named odor.
HABITS AND ECONOMIC IMPORTANCE
Although the Argentine ant affects our interests in many ways, it
has made itself notorious primarily as a house-infesting insect. In
the South this species invades the house almost continuously
throughout the year, even in winter when temperatures are as low
as 50 F. When a property is heavily infested, the ants may be
found not only in pantries, dining rooms (fig. 2), and kitchens, but
even in refrigerators, beds, etc. In certain sections dwellings have
been vacated because of the ravages of this pest. The presence of
the ants in a house cannot be taken as reflection on the neatness of
the housekeeper, as many houses kept spotlessly clean are invaded.
Late in the summer and especially after heavy rains, perhaps be-
cause the honeydew has been washed off the -plants outside, the ants
become unusually troublesome in the house.
The Argentine ant is practically omnivorous in its feeding habits.
If it has any preference for foods, this would seem to be sweets.
A scum of dead ants from one-eighth to one-fourth inch deep has
been seen in cans containing table sirup. Sugar, jelly, pies, and
candies are consumed with relish. The ant will crawl on top of a
block of ice to reach meat lying there. Occasionally it feeds even on
. Outdoors the ants make themselves noticeable by their numbers
as well as by the damage they do. In some sections they are so
ARGENTINE ANT IN THE UNITED STATES 5
every cell had been emptied of its honey content by Argentine ant
As far as known, no one has proved that the Argentine ant
transmits human diseases. The workers' habit of visiting garbage,
refuse, feces, sputum in fact, anything that might harbor disease
germs suggests that they might easily transmit such diseases as
typhoid fever, diarrhea, and tuberculosis. Horton (8) has sug-
gested that the workers may also transmit certain plant diseases
through their habit of feeding on the sap flowing from, the wounds
Argentine ants differ from native ants in that, once they have be-
come established on a property, they will usually not tolerate other
species. Therefore, instead of many different kinds of ants on a
property, there is ordinarily an abundance of only one, the Argentine
ant. The author has often witnessed combats in the field between
native and Argentine ants. It is not unusual to see five or six Argen-
tine ants attack a single native ant. Although some of the native ants
have the advantage in size, or by the possession of a sting, they
finally succumb to the attack of these South American invaders
because they are outnumbered.
The fact that the Argentine ant destroys practically all the native
ants as it advances makes it comparatively easy to delimit an area
infested by them. One must not conclude, however, that after
Argentine ants are eradicated from an area, that area will be free
of native ants also. Just as soon as the Argentine ants begin to
disappear, native ants invade the territory, and within a very few
years are apparently as plentiful as ever. In Mississippi the fire
ant Solenopsis xyloni McCook, an arch enemy of the Argentine
ant and often mistaken for it, is usually the most abundant native
species following the eradication of the Argentine ant.
DISTRIBUTION AND ABUNDANCE
MEANS OF SPREAD
The unusually rapid spread of the Argentine ant has been due
to its ability to produce prodigious numbers, its habit of extermi-
nating competitive species as it spreads, its lack of natural enemies,
its omnivorous feeding habits, and especially to its ability to thrive
in human habitations as well as in rural sections.
Its distribution hasi been accomplished by both artificial and nat-
ural means. Artificial spread has been by far the more important.
Common carriers and merchandise have transported the ants great
distances, thus establishing infestations in localities remote from
one another. Along the important railroad lines in the Southern
States, especially those in the Gulf coast section leading out of New
Orleans, nearly every locality of any commercial importance is
the seat of an Argentine ant infestation. Such cities as New Or-
leans, Birmingham, Montgomery, and Atlanta have served as focal
centers for the distribution of the ants in neighboring towns and
rural areas. The ants can be carried in shipments of lumber, plants,
dry goods, groceries, etc. The spread by means of boats and rafts
has not been so great as by railroad, because there is less water
transportation, but in areas where water transportation is common,
ARGENTINE ANT IN THE UNITED STATES 9
Argentine ants have been found at altitudes ranging from approxi-
mately sea level (3 feet) to as high as 3,955 .feet.
So far as could be observed, the ants are capable of living under
a great variety of soil conditions. They have been found in soils hav-
ing textures ranging from light sandy loams to clay loams, with
poor to good drainage, and with varying amounts of organic matter,
including the soils of the stream bottoms, of the prairies, and of the
marshes, as well as those of the uplands.
It was found that certain types of vegetation seem to attract the
Argentine ant more than others. The presence of aphids, mealy-
bugs, scale insects, and other honeydew-producing forms is undoubt-
edly the reason for such preference. Trees that are especially
frequented include oaks (chiefly water and live oaks), willow, hack-
berry, pecan, sweetgum, pine, fig, maple, elm, and citrus.
GENERAL DISTRIBUTION IN THE UNITED STATES
Argentine ant infestations have been found in nearly one-third of
our States (fig. 6). The total area infested is approximately 4,000
square miles. Practically all the infested areas, with the exception
of those in California, are in the Southern States, chiefly in the Gulf
coast section. The infestations in Arizona, Missouri, Illinois, and
Maryland appear to be isolated, and of these only that in Arizona
is typically an outdoor type, as in the other States the ants appear to
survive the winter only in buildings, especially those that are heated.
In a heavily populated urban area, where the houses are practically
contiguous, particularly in northern locations, the ants might spread
from'house to house until they occupy all or most of the city, because
of their ability to survive winter conditions in the interior of buildings.
The Argentine ant has spread more rapidly eastward from New
Orleans than it has westward or northward. Except for California
and a single infestation in Arizona, it is not found farther west than
the eastern half of Texas. In the northern parts of Alabama and
Mississippi infested areas are few and small, and in northern Louis-
iana there are practically none.
Baleigh, N. C., is the most northern locality in the Eastern States
where the ant has been found to live outdoors and survive winter
temperatures. The infestation here is at least 15 or 16 years old,
having been found by the author (14) in September 1919, and as yet
it apparently extends only about 0.15 square mile. The slow spread
of the ants in Ealeigh is an indication that they are very near the
northern limit of distribution under outdoor conditions. An out-
door infestation at Nashville, Tenn., found by Barber was exter-
minated within a year, presumably by severe winter weather. Bar-
ber also found the ants at Memphis several years ago, but neither
the scouts of the Bureau of Entomology nor representatives of the
office of the State entomologist of Tennessee have been able to find
any there in recent years.
In Mississippi, however, where there were only about a dozen
known infestations in 1910 (Harned and Smith (5) ) , in 1934 there
were at least 245, exclusive of the isolated areas within many of the
infested towns. Inspectional work, of the State Plant Board of
Mississippi has retarded the spread of the ant considerably, and
were it not for such service the situation would be much worse.
41271 36 2
.CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
ARGENTINE ANT IN THE UNITED STATES 11
From what is known of the habits and distribution of the Argen-
tine ant in Mississippi, it is probable that there are isolated rural
infestations in many of the States, especially in the Gulf coast region.
In Monroe County, Miss., 17 rural infestations are known. Of the
known infestations in Mississippi, 26.7 percent are in rural com-
Unless controlled, it seems likely that the ants will in time be gen-
erally, if not continuously, distributed throughout those Southern
States in which numerous scattered infestations now occur. In ad-
dition they will probably occur in most of the southern half of
North Carolina, the extreme southern part of Tennessee, the southern
half of Arkansas, the extreme southern part of Oklahoma, the eastern
half of Texas, as well as in a large part of California, particularly
in the lower altitudes.
OCCURRENCE AND ABUNDANCE IN THE INFESTED STATES
The information on the occurrence of the Argentine ant obtained
by scouting or through correspondence is summarized in table 1 and
in the following paragraphs. Of the 18 States where scouting was
conducted, 13 were found infested.
CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
or* wo co
1-H O ^ O ^
N rf 'g
1 Texarkana included in both Texas and Arkansas totals.
jfsii "I 1"
cs " S
t-> CO O t-.
o O) r~. e
' CO * ^ i-J (O
^ OOC-J 10 O M
i-( CO (N
i 1 CO
O t^- TJ< Oi 'O O "O
General area scouted
ern and southern...
re totate . .
re State except Echols County
hern and aloug Illinois Central R. R.
them and western--
a supplied by State Plant Board
ns near Missouri and Mississippi Eiv
hwestern _ _
ern, southern, and western
hern and western^ .......
ern half, few localities in western
est cities in southern half
of largest cities _
o 03 oj !>
Arizona __ __ ___
California.. _ _.
| o 1
o |_ .s ; |
ARGENTINE ANT IN THE UNITED STATES
Although the infestations in Alabama are rather generally dis-
tributed over the State, they are more numerous in the central part
and less prevalent in the northern part (fig. 7). Jefferson County,
with 10 infested localities, and Wilcox County, with 7, are the two
most heavily infested counties. Many of the infestations are ex-
tremely small, indicating that they are recent. The largest infesta-
tion is at Birmingham and embraces 124.02 square miles. Mont-
gomery follows with
31.39 square miles,
and Mobile third with
10.44 square miles.
Practically all the
from articles shipped
by railroad. A few
towns, however, appar-
ently became infested
through truck or water
ham is an excellent
example of a large
commercial city that
has become a focal cen-
ter for the spread of
the ants to nearly all
the small towns in its
The scouting in Ari-
zona was confined prin-
cipally to the southern
third of the State, but
examinations were also
made in two locali-
ties north of Phoenix,
Prescott and Kingma.n.
The localities chosen
were the most impor-
tant commercial points
along the main high-
FIGURE 7. Map of Alabama showing number of localities
scouted for Argentine ants and the infested localities
^ (dots) in each county.
ways and railroad
lines. They were as follows: Tombstone, Bisbee, Lowell, Douglas
(Cochise County), Safford (Graham County), Phoenix, Tempe,
Mesa, Glendale, Buckeye, Gila Bend, and AVickenburg (Mancopa
County), Kingman (Mohave County), Tucson (Pima County),
Nogales (Santa Cruz County), Prescott (Yavapai County), and
Well ton and Yuma (Yuma County).
The single infestation in the State is at Douglas, in Cochise
14 CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
In Arkansas the localities scouted were confined for the most part
to the larger and more important railroad junctions or river towns
in the eastern and southern sections of the State. The river towns
lay along the banks of the White, Arkansas, and Mississippi Rivers.
The localities scouted were as follows: Blytheville, Osceola, Wilson
(Mississippi County), Marion (Crittenden County), Forrest City
(St. Francis County), Marianna (Lee County). Helena and Barton
(Phillips County), Clarendon (Monroe County), DeValls Bluff and
Des Arc (Prairie County), Searcy (White County), Little Rock
(Pulaski County), Benton (Saline County), Pine Bluff (Jefferson
County), McGehee and Arkansas City (Desha County), Lake Village
(Chicot County), El Dorado (Union County), Camden (Ouachita
Arkadelphia (Clark County), Malvem (Hot Sprin^
Hot Springs (Garland County), De Queen (Sevier
Ashdown (Little River County), Texarkana (Miller
County, Ark., and Bowie County, Tex.).
. Of the two infestations found, that at Hot Springs is very small,
only 0.04 square mile, while that at Texarkana is rather large, com-
prising four separate areas which cover a total of 3.38 square miles.
Both infestations probably originated from railroad 'shipments.
Although the eastern and southern sections of the State border on
Mississippi and Louisiana, respectively, the lack of infestations in
these sections is probably due to -the fact that neither northern
Louisiana nor northwestern Mississippi is as yet heavily infested.
The distribution of the Argentine ant in California can only be
summarized here in a general way, because the Bureau of Entomology
did no scouting in this State, nor has the exact distribution been
determined by the State _ authorities. The information given below
and on the map (fig. 8) was kindly furnished by Harry S. Smith,
of the Citrus Experiment Station at Riverside, Calif., and repre-
sents a summary of reports supplied him by county agricultural
The San Francisco Bay district including the Santa Clara Val-
ley and the coastal plain to the south, the San Joaquin Valley south
of and including Sacramento County, a considerable part of Los
Angeles and Orange Counties, and western San Bernardino, River-
side, and San Diego Counties may be said to be generally infested ;
that is, colonies of ants were found in every residence and on a con-
siderable portion of the orchard acreage. Dr. Smith is of the
opinion that there are at least 2,000 square miles of infested territory
in California, and that this area is far greater than in any other
State. He says :
The ant has been here for more than 30 years, conditions are ideal for
its development, and the unusually extensive .distribution of balled ornamentals
has seemed to disseminate it very widely.
In Florida the known infestations are in the northeastern and
northwestern sections of the State (fig. 9). As yet none of the infes-
ARGENTINE ANT IN THE UNITED STATES
tations is large, that at Pensacola (Escambia County) being the
largest, with 3 separate areas totaling 0.20 square mile. Caryville
(Washington County) has 0.11 square mile, and Palatka (Putnam
County) and Jacksonville (Duval County) 0.06 square mile each.
The history of these infestations is rather obscure, but it is probable
that boats and railroads played almost equal parts in carrying the
ant to this State.
That Florida has so few infestations is surprising in view of the
many factors that might aid the ant in becoming established there,
tgSij Ceneraf/t/ distributed in settled portions
Scarce or uncertain
Y//. J '.''.I Not known to be present
I I 'No reports
FIGUKB 8. Map of California showing Argentine ant distribution.
such as a semitropical or mild climate, a heavy tourist trade, and
opportunities for the ants to come in by both boat and railroad.
Georgia (fig. 10) is not so generally infested as Alabama, the in-
festations being confined largely to the northwestern part, especially
the area lying between Columbus and Atlanta. The extreme south-
eastern, southwestern, and northern sections are practically free
from infestations. The most heavily infested counties are Coweta,
Troup, and Fulton. A large number of these infested areas lie along
CIRCULAR 387, tf. S. DEPARTMENT OF AGRICULTURE
the Atlanta and West Point Railroad. Most of the infestations in
Georgia, like those in Alabama, without doubt originated from ants
infesting products shipped by railroad.
The largest infested area in the State is at Atlanta, comprising
26.70 square miles. The next largest are Newnan, 13.68 square miles ;
Moreland and St. Charles together, 12.48 square miles ; and Augusta,
8.15 square miles. Atlanta, like Birmingham, has been the source
of infestation of many of the surrounding small towns.
FIGURE 9. Map of Florida showing- number of localities scouted for Argentine ants and
the Infested localities (dots) in each county.
In Illinois the following towns were surveyed : Cairo (Alexander
County), Champaign and Tolono (Champaign County), Mattoon
( Coles County), Neoga (Cumberland County), Arcola and Tuscola
(Douglas County), Edgewood and Effingham (Effingham County),
Carbondale and De Soto (Jackson County), Vienna (Johnson
County), Centralia, Odin, Salem, Alma, and Kinimindy (Marion
County), Metropolis (Massac County), DuQuoin and Tamaroa
(Perry County), Mounds and Ullin (Pulaski County), Harrisburg
(Saline County), Anna (Union County), Ashley (Washington
County) , and Marion (Williamson County) .
No Argentine ants were found as a result of the scouting, but the
species is established in the Zoology Building at the University of
ARGENTINE ANT IN THE UNITED STATES
Chicago.* This infestation supposedly originated in 1906 from
ants introduced on plant material for use in connection with investi-
tations on the Colorado potato beetle '(Leptinotarsa decemlineata
ay). Colonies are located in the basement of the building and oc-
casionally cause considerable annoyance in the laboratories. Al-
though in warm weather the ants are found outdoors a number of
feet from the building, they have not spread to other buildings or
FiGciiB 10. Map of Georgia showing number of localities scouted for Argentine ants and
the infested localities (dots) in each county.
over the campus. Apparently they are able to survive the winter
Scouting in Kentucky was confined to the northern parts lying
along the Ohio and Mississippi Rivers, and also along the Illinois
4 Data on this infestation were supplied by Mary Talbot, of the University of Chicago,
and V. E. Shelford, of the University of Illinois.
41271 36 3
18 CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
Central Railroad in the extreme western part of the State. The
localities examined were as follows : Wickliffe and East Cairo (Bal-
lard County), Wellsburg (Bracken County), Petersburg (Boone
County) , Holt (Breckinridge County), Catlettsburg and Ashland
(Boyd County), Bardwell (Carlisle County), Carrollton (Carroll
:County), Weston (Crittenden County), Owensboro (Daviess
County), Hickman and Fulton (Fulton County), Warsaw (Gallatin
County), Greenup (Greenup County), Clinton and Columbus
(Hickman County), Hawesville (Hancock County), Covington
(Kenton County), Louisville (Jefferson County), Vanceburg
(Lewis County), Smithland (Livingston County), Maysville (Ma-
son County), Paducah (McCracken County), Brandenburg (Meade
County), Westport (Oldham County), Henderson (Henderson
County), and Uniontown (Union County). No Argentine ants were
found. The known infestations nearest to Kentucky are in the
extreme southern part cf Tennessee.
In Louisiana the ant occurs not only in cities and towns, but in
rural or sparsely settled areas, and in almost impenetrable swamps.
The southern half of the State is not only generally but heavily
infested, whereas in the northern part there are only a few widely
separated infestations (fig. 11). Although the heavier infestation
in the southern half of the State .might be attributed to the milder
climate and the earlier appearance of the ants, it is probably due
largely to spread by floods and boats.
The importance of railroad lines in the dissemination of the ants
is clearly shown in Tangipahoa Parish, where 10 of 13 localities
along the Illinois Central Eailroad were found infested. There are
more large infestations in Louisiana than in any other State. Such
infestations range from 10 to 35 square miles on an average, and
there are several as large as 120 to 135 square miles. Owing to their
inaccessibility, many localities, especially in the southern part of the
State, were not scouted. The infested area is therefore probably
larger than that given in table 1.
N"o scouting was carried on by the Bureau of Entomology in
Maryland. The author first learned of the occurrence of the Argen-
tine ant in this State when he received from E. N. Cory, State ento-
mologist, specimens collected from the Clifton Park greenhouses in
Baltimore. Later investigations by Dr. Cory and members of his staff
revealed the presence of this ant in greenhouses at the following
parks in Baltimore: Druid Hill, Carroll, Patterson, and Clifton.
On October 7, 1931, the author and D. W. Hookpm, of the Uni-
versity of Maryland Department of Entomolgy, visited greenhouses
in both Clifton and Carroll Parks where the Argentine ants -were
established. At Carroll Park colonies were found nesting outdoors
: 75 yards from the greenhouse, but at Clifton Park the ants were
not more than 10 feet away. Little definite information regarding
the history of the infestation could be obtained. Judging from the
abundance of the ants at Carroll Park and from statements of green-
ARGENTINE AST IN THE UNITED STATES
house attendants, they undoubtedly have been present there for
As a result of an investigation during the winter of 1931, Mr.
Hookom found that the ants lived outdoors in protected places, but
the winter was comparatively mild.
In Mississippi scouting for Argentine ants Avas confined to 24
localities in the extreme northern part of the State, because the State
Plant Board was rather well posted as to the general distribution
FIGUKE 11. Map of Louisiana showing the infested localities (dots) in each county.
of the ant elsewhere. The summary of conditions in Mississippi is
based on records of both the Mississippi State Plant Board and the
Federal Bureau of Entomology.
Although the ant is generally distributed throughout the State
(fig. 12), it is most abundant in the southern and central sections,
and least abundant in the northwestern portion. Eailroads have
been the principal means of spread. So clearly is thig indicated that
one can locate the important railroad lines in the State by following
on the map the dots representing the infested localities. The most
heavily infested counties are Monroe, Hinds, Attala, and Holmes.
Many of the infestations are small, but in gome of the towns the
infestation covers the entire incorporated area and extends into the
country for several miles. Those at Jackson, Meridian, and Kosci-
CIRCULAR 387, TJ. S. DEPARTMENT OF AGRICULTURE
usko undoubtedly cover from 12 to 15 square miles each. In a num-
ber of towns there is more than one infested area; at Columbus,
for example, 18 isolated infestations have been found. A large
number of the infestations, particularly in the heavily infested
counties, occur in rural areas, and these no doubt originated through
introduction of groceries or other products from neighboring towns.
Kecent intensive" scouting shows that 39 of the 245 infested locali-
ties have been freed of the pest, as a result of poisoning campaigns.
The following towns
were scouted in Mis-
souri : Poplar Bluff
(Butler County), Cape
Girardeau and Delta
County), Jefferson City
(Cole County), Boon-
ville (Cooper County),
County) , Hermann
(Gasconade County ) ,
sippi County), New
Madrid (New Madrid
County) , S e d a 1 i a
(Pettis County), Ca-
County), Ste. Gene-
vieve (Ste. Genevieve
County), and St. Louis
(St. Louis County).
Argentine ants were
found in St. Louis, but
only at the Missouri
Botanical Gardens and
in a nursery nearby.
From the information
obtained it does not
seem possible for the
ants to survive outdoor
winter conditions here.
Within the greenhouses
and other heated buildings the ants seem to thrive and are making
themselves objectionable through their attendance on aphids and
mealybugs. Only two infestations are known to occur farther north
than the one in St. Louis, and both of these are also of the indoor
The towns scouted in New Mexico lie along the railroad lines and
are as follows : Las Cruces, Hatch, Rincon, and Mesilla Park (Dona
Ana County), Silver City (Grant County). Lordsburg and Kodeo
9 /nfestecf /oca/ities
n Localities from which the
hare been eradicated
^Loca/ities from tvf)/ch the an
hare aaparGnt/y been eradicated
FIGURE 12. Map of Mississippi showing status of
Argentine ant infestations.
ARGENTINE ANT IN THE UNITED STATES 21
(Hidalgo County), and Iteming and Cambray (Luna County).
Although the scouting was limited, it does not appear likely that the
ants occur in this State.
In North Carolina the known infestations are confined to the
southern and central or east-central sections (fig. 13). None of the
infested areas is very large, that at Wilmington, with two areas
totaling 1.23 square miles, being the largest and apparently the
oldest. The infestation at Goldsboro. covering 0.60 square mile, is
FICJUKE 13. Map of North Carolina showing number of localities scouted for Argentine
ants and the infested localities (dots) in each county.
next in size, while that at Raleigh is only 0.15 square mile. It is
surprising that no infestation was found in the small towns near
The following localities in southern Oklahoma were scouted : An-
adarko (Caddo County), Durant (Bryan County), Ardmore (Carter
County), Coalgate (Coal County), Lawton (Comanche County),
Hugo (Chocktaw County), Clinton (Custer County), Pauls Valley
and Lindsay (Garvin County), Chickasha (Grady County), Holden-
ville (Hughes County), Altus (Jackson County), Mangum (Greer
County^, Hobart and Snyder (Kiowa County), Madill (Marshall
County), Valliant and Idabel (McCurtain County), McAlester
(Pittsburg County), Ada (Pontotoc County), and Frederick (Till-
man County). That no ants could be found in southern Oklahoma
is surprising, since a number of infested localities in northeastern
Texas are not more than 50 to 75 miles away. A vigilant watch
should be kept for the appearance of the ants in this section of the
In South Carolina the ant was found to be fairly well scattered
over the State, but was most prevalent in the southeastern, east-
central, and northern sections (fig. 14). Spartanburg County, with
five infestations, has the largest number ; Greenville County second,
with four; and Charleston County third, with two.
The largest infestation in the State, and undoubtedly the oldest, is
that at Charleston, which was estimated to cover 6.29 square miles.
22 CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
The next largest infestation is at Spartanburg, which occupies 2.20
square miles, and that at Gaffney third, with 1.12 square miles. In
several towns there is more than 1 infestation, Spartanburg having
12 and Greenville and Gaffney 3 each.
The importance, of the railroad in distributing the ant is clearly
shown in Greenville and Spartanburg Counties, where nearly all the
infestations lie along the main line of the Southern Railroad. Many
of the towns in the vicinity of Charleston, where the ant has been
known for at least 19 years, are apparently not infested. :
FIGUEE 14. Map of South Carolina showing 'number of localities scouted for Argentine
ants and the infested localities (dots) in each county.
In the southern part of Tennessee only the larger and more impor-
tant commercial towns were scouted, and in the western section the
work was confined to towns along the main line of the Illinois Cen-
tral Railroad and the Mississippi River. Infestations were found
in the extreme southern part of the State not far from the Alabama
line, one at Pulaski in Giles County and another at Fayetteville in
Lincoln County. It was surprising that no Argentine ants were
found at Memphis or in any of the larger towns along the railroad -
The Argentine ant was found to be rather generally distributed
over the eastern half of Texas, or that section lying east of Wichita
"Falls and Austin (fig. 15). This was to be expected in view of its
nearness to Louisiana, its rather densely populated areas, and the
more abundant vegetation here than in the western part of the State.
ARGENTINE ANT IX THE UNITED STATES
The largest infestations in the State are as follows : Beaumont, 11.4
square miles; Fort Worth, 11.37 square miles; Houston, 8.32 square
miles; Dallas, 5.07 square miles. In spite of the large number of
localities infested in Texas, the State is much less heavily infested
than the States east of Louisiana.
Apparently all but a. very few of the infestations were started from
produce shipped on railroads. The ant has not become established
in many of the towns along the Gulf of Mexico, either because large
boats do not come into these towns or because the boats are usually
not from ports infested with Argentine ants. Frequent direct water
FIGOIIE 15. Map of Texas showing number of localities scouted for Argentine ants and
the infested localities (clots) in each county.
communication between Louisiana and the southeastern section of
Texas would no doubt hasten the establishment of the ants there.
The following cities in Virginia were scouted: Lynchburg (Camp-
bell County), Richmond (Henrico County), Petersburg (Dinwiddie
County), Suffolk (Nansemond County), Norfolk (Norfolk County),
Roanoke (Roanoke County), and Lexington (Rockbridge County).
The occurrence of the Argentine ant at Norfolk had been reported
in correspondence, but H. T. Vanderf ord was unable to find any ants
after a 5-day search. The limited scouting failed to reveal any ants
in the State.
24 CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
Less scouting was done in West Virginia than in any other State.
Outdoor infestations so far north did not seem probable, especially
since no typical ones had been found north of Ealeigh, N". C. In
passing through this State to Kentucky, the scouts spent 4 clays in
Huntington (Cabell County) and Charleston (Kanawha County),
with negative results.
CONTROL AND ERADICATION WORK IN MISSISSIPPI
According to Harned (-5) Argentine ants probably made their
first appearance in Mississippi about the year 1900, and by 1909
there were- approximately a dozen known infestations in the State.
By 1922 infestations in 40 towns had been recorded, and in 1934, 245
infestations had been found. Since only about half a dozen new
infestations had been discovered during the previous year, it was
presumed that most of the infested areas in Mississippi had been
As the number and severity of the infestations increased, ana
property owners found that their own efforts to combat the pest with
commercial poisons were either futile or at least only temporarily
beneficial, they appealed to the State officials for help. By this time
E. R. Barber, an investigator for the Federal Bureau of Entomology,
had proved that the ants could not only be controlled but prac-
tically eradicated in small areas. Control campaigns were therefore!
inaugurated through a cooperative arrangement between the State
Plant Board and the infested communities,, with the assistance of
Mr. Barber in directing the work. The first of these campaigns were
conducted in four towns Durant, Laurel, Crystal Springs, and
Woodville during the fall of 1920, and they were so successful that
others were undertaken in the following years. Since 1920 the plant
board has supervised this work, while the municipalities and coun-
ties have paid the expenses. This work reached its height in 1929,
when 121 localities were poisoned for the ants, 1,136,028 cups of
poison being used at a cost of approximately $35,000. Even in the
depression years there has been a steady demand for control work,
although the towns and counties have been handicapped by lack of
The early campaigns were designated control campaigns, and the
word "eradication" was not used. In 1924, however, an area em-
bracing a block and a half at Fayette, Miss., was freed of the ants
after two successive fall campaigns, at an exceedingly low cost (15).
So far as is known, this was the first town, not only in Mississippi
but in the world, from which the ants had been eradicated. Later
cither towns began to eradicate the ants, and by 1928 six Fayette,
Shaw, Lyman, Landon, Moss Point, and State College had been
freed of them (4). Since then State authorities have not only
stressed the fact that it is possible to eradicate Argentine ants by
timely 'and thorough campaigns repeated for several consecutive
years, but they have encouraged the municipalities and counties to
fight the ants in this manner.
Since it has been definitely shown that both control and eradica-
tion of Argentine ants can be achieved by the method used in Missis-
ARGENTINE ANT IN THE UNITED STATES
sippi, it is desirable to describe- in detail how this is accomplished
and to give some idea as to the cost of the work.
SURVEYING INFESTED AREAS
Usually there is only one general infestation in a town, although
in some towns as many as 15 to 20 isolated areas have been found.
The ideal method of locating and delimiting infestations would be
to scout the entire town, property by property, and block by block,
but this is both costly and time-consuming. The plant board has
therefore not attempted to scout entire towns with such thorough-
ness unless the town authorities have indicated their intention of
. ... _ \ ^-^
QRES. i^i LARGE
1 1 RES.
M\l i nmiiliiiiiniiililiiiiiiinmiiimiHiiii
WATER TANK O
G. M. AND N. R. R.
FIGCBK 16. Map of an area infested with Argentine ants, showing the number of cups
of poison required fur the various blocks.
continuing the work until eradication is accomplished. It is pos-
sible, however, to determine the limits of an infested area without
visiting every property or block. Since the Argentine ant destroys
practically all the native ants, wherever native ants are found one
can be reasonably sure that there are no Argentine ants. If the
scout, therefore, proceeds from a given point of infestation and
examines trees, fences, the ground, and the bases of pillars of build-
ings, he can consider that he has reached the limit of the infested
area when he first encounters native ants instead of Argentine ants.
From this point he encircles the infested area and as he finds the
division between the infested and the noninfested territory he in-i
dicates it on a map (fig. 16). When the circle is completed he is in
a position to estimate the cost of poisoning that area.
26 .CIRCULAR 387, u. s. DEPARTMENT OF AGRICULTURE
ESTIMATING THE COST OF A CAMPAIGN
The cost of a campaign is estimated on the basis of the number of
cups required. In an ordinary city block this will range from 100 to
200. One familiar with the work can estimate roughly the number
needed after walking around the block, but a less experienced person
should note the places where cups are needed, spacing them 20 to 25
feet apart, regardless of the character of the block with respect to
vegetation, buildings, fences, etc. In areas not bounded by streets
the estimate should be made in such a way as to avoid confusion.
The number of cups of poison required for each block in the infested
area is indicated on the map (fig. 16). The total number of cups
required for all the blocks and other areas is then computed. It is
advisable to give the totals in even thousands, for manufacturers
prefer to ship in such lots.
The cost of supplies and labor for a campaign that will require
6,000 cups is estimated, on the basis of current prices, to be about
as follows :
6,000 paperoid cups, at $9.25 per 1,000 $55.50
6,000 brackets, at $3.25 per l,000-__, 19. 50
75 gallons of poison, at 60 cents per gallon 45. 00
12 pounds of shingle nails, at 5 cents per pound . 60
Incidentals (four 5-gallon kerosene cans, 1 bucket, 1 funnel, 4 hammers,
4 grocery baskets) 6. 00
Express or freight on supplies 2. 00
Labor, 120 hours at 20 cents per liour 24. 00
Cost per cup . 0254
In Mississippi many campaigns have been put on at an average of
from 2.3 to 3 cents per cup. A well-conducted campaign should
seldom cost more than 3 cents per cup.
During the course of the control and eradication work in Missis-
sippi three types of poison containers have been used tin cans,
aluminum cups, and paperoid cups (fig. 17).
Tin cans with detachable lids, measuring 2% .by 4 inches with a
capacity of approximately 10 fluid ounces, were first used. Two in-
dentations were made at the top with pliers, which when the lids
were placed on the cans formed holes through which the ants might
pass. To attach a can to. a tree, post, or building, a six-penny nail
was driven into the object and the can hung over it through one of
the holes beneath the lid. Formerly a gill of poison and .a piece of
sponge about the size of an egg were placed in each can, the sponge
serving as a footing for the ants as they fed. It was later found that
the sponge was unnecessary and that 1 to iy 2 ounces of sirup per can
The tin can was finally discarded because of its high cost. The cost
of the early campaigns averaged from 6 to 7.5 cents per can, and
from 2.2 to 2.5 cents of this was for the can. The tin can, however,
is somewhat more substantial than the other containers and, because
ARGENTINE ANT IN THE UNITED STATES 33
such conditions. The cost of control work prevents most localities
from attempting more than one campaign a year. Moreover, such
splendid results have been obtained in Mississippi from fall cam-
paigns that there has been no incentive for putting on spring
REACTION OF ANTS TO THE POISON
All the cups of poison are not visited at once by the ants. When
feeding does take place, the ants visit the poison rather regularly and
in large numbers for from 6 weeks to 2 months, after which time
they attend it at infrequent intervals and then only in small num-
bers. Cups placed on trees, fences, and houses are visited most fre-
quently. It has been noticed that when the sirup begins to thicken
its palatability for the ants greatly decreases, and within a year
it ceases to attract them, although many of the cups are not yet
empty. It is generally believed that worker ants and their brood
die within a few days after having fed on the poison. The greatest
reduction in the number of ants evidently takes place during the
first 2 months after the poison has been distributed.
DETERMINING THE EFFECTIVENESS OF A CAMPAIGN
In the summer following a campaign a survey is made by plant
board inspectors to ascertain its effectiveness. Inquiries are made
of housekeepers, storekeepers, cafe owners, and hotel managers as
to the situation on their property. This is rated as "good" if no
ants have been seen in their buildings since the poisoning, "fair"
if few ants have been in evidence, and "poor" if the ants have been
as abundant as before the poisoning. The "good" and "fair" reports
are considered, as satisfactory, the "poor" as unsatisfactory. Fol-
lowing the first campaign in a locality, from 95 to 100 percent of the
reports are usually satisfactory, and .after successive campaigns
have been put on 100 percent of the reports are often satisfactory.
In obtaining these reports it is necessary to be cautious, especially
near the edge of the infested area, lest the property owner mistake
native ants for Argentine ants. Some of the native ants cannot
be controlled by this poison.
When the first campaign in a locality has been put on in a
thorough manner, the abundance of the ants is usually so greatly
reduced that few homes are troubled with them any more and the
residents often conclude that they have been eradicated. This is
rather unfortunate, for it is difficult for the plant board to induce
that locality to put on a follow-up campaign. It is customary for
the plant board to publish in the local paper a short account of the
investigation, informing the public that, although the ants have
been greatly reduced in numbers, they have not been eradicated.
In putting on the second fall campaign, the same quantity of
supplies as in the first campaign should be used. The summer after
the second campaign the infested area can be scouted to determine
what sections have been freed of the ants and to what extent the
quantity of supplies can be reduced for the next campaign.
Many towns will poison the ants one fall and then wait until
they become annoying again before putting on another campaign.
34 CIRCULAR 387, IT. S. DEPARTMENT OF AGRICULTURE
Such a course is always discouraged by the plant board, as the
ants can reach their former numbers and cause serious annoyance
within 2 or 3 years.
The Argentine ant can be controlled by one thorough campaign,
but these campaigns must be repeated if eradication is desired.
Occasionally two campaigns are sufficient, but usually from three
to five, and occasionally more, are necessary. To be successful,
however, especial attention must be paid to the timeliness and thor-
oughness of the work and to the protection of the cups. If eradica-
tion has not been achieved after the second campaign, further treat-
ment depends on the abundance of the ants. If they are still widely
distributed and fairly abundant, a third general campaign with
the same quantities of supplies as before is advisable. If, however,
only a few colonies are found in a block, it is sufficient to repoison
the infested spots, including an area within a radius of about 50
feet. Fresh poison should be applied immediately and again in the
fall. The intensive follow-up scouting should be continued for two
summers after the area appears to be free from the ants.
Although it has been shown that the ants can be eradicated from
given areas by poisoning alone, it is frequently desirable to hasten
eradication by supplementary measures such as burning and oiling.
In woodland areas where the ants are colonized in stumps, logs,
and rotton" branches of trees, many strong colonies can be destroyed
by making fires in the woods and burning all the movable wood
containing colonies. Stumps and immovable logs (fig. 24) can be
burned by pouring on kerosene and setting them afire:
The burning should be done when the wood is dry and there is
no wind. The best time for this is probably late in the fall or in
winter, when the temperature is 50 F. or lower and the ants in their
nests are inactive. The fires should be carefully guarded to prevent
them from getting out of control and starting woodland fires. With
labor in the South ordinarily not costing more than 12.5 cents an
hour, and kerosene selling at 14 cents a gallon, the cost of treating
is not more than $2 to $3 per acre.
Digging colonies out of the soil and burning them with a blow-
torch is such a. laborious task that it is prohibitive except where the
ants have been almost completely exterminated. It is doubtful if
it would be practical where there are more than one or two colonies
per block. This work requires a higher type of labor than some of
the other control work. It sometimes takes half a day or longer to
burn out a large colony, which has many ramifying galleries in the
soil. As a worker can only burn, from one to three colonies a day
by this method, the eradication of each colony would cost from
$1.25 to $4. Waste oil, such as can be obtained from filling stations,
is used to saturate the ground where the colony is dug up. From 3
to 4 gallons will saturate the ordinary nest.
The towns that have eradicated Argentine ants in Mississippi have
used diverse methods in accomplishing this. In the 21 areas investi-
gated by the Bureau of Entomolgy, the total cost of eradication per
block has varied considerably. Since the adoption of the paper cups,
36 CIRCULAR 387, U. S. DEPARTMENT OF AGRICULTURE
METHOD RECOMMENDED FOR THE CONTROL OR ERADICATION OF
THE ARGENTINE ANT
The first step in the campaign is to delimit the infested area.
Scouting for this purpose should be done late in the summer or early
in the fall, and never when the temperature is below 65 to 70 F.
In connection with the scouting a map of the infested area should
be prepared which will not only be accurate, but clear to anyone using
it. It should be drawn on such a scale that it can conveniently be
used in the field. In addition to indicating the blocks and streets,
it will prove helpful to note important landmarks, especially in
those sections not represented by streets. The number of. cups of
poison required for each block can be indicated on the map.
The campaign should be put on in the fall or winter, when there
is so little natural food available that the poison will prove attractive
to the ants. For the comfort of the men it is best to do this in mild
The poisoned bait recommended is the "standard Government-
formula Argentine ant poison", which is a sirup containing sodium
arsenite. Before being distributed it should be analyzed by a chem-
ist, and if it does not meet the specifications it should be discarded.
The most satisfactory type of container for the poison is the paper-
oid cup. The most practical and economical method of filling the
cups is in the field from tanks carried on the backs of the field crew.
The cups should be placed from 20 to 25 feet apart, and they should
be concealed as much as possible. On trees and posts they should be
tacked as high as one can reach. On fences they are preferably
placed low and, if the fence encloses domestic animals, outside the
enclosure. Under houses that are open underneath, the cups can be
put on the top of every third or fourth pillar, and under houses that
are enclosed the cups can be fastened on the walls about 20 feet apart
and as high as one can reach. Where there are no objects on which
to tack the cups, they should be; buried in the ground or placed in
clumps of grass or bushes.
It is important to select the best type of labor available, as the
success of the campaign is largely dependent on the thoroughness of
the work. The men should be instructed before the work is begun
and carefully supervised throughout the campaign.
On the completion of the campaign, an article should be prepared
for a local newspaper explaining the nature of the poison, how it
affects the ants, and the results that may be expected. Protection
of the- cups should be especially urged. An appeal to the children
not to touch the cups can be directed through the superintendent of
public schools. The aid of the Boy Scouts can also be enlisted.
The following summer the effectiveness of the campaign should be
determined by questioning property owners, and the results of this
survey published at once in the local paper. Later the margins of
the entire infested area should be scouted to ascertain if the ants
have spread since the previous fall or if any infested areas have been,
overlooked. The results of this scouting should be indicated on the
same map that was used in the preliminary scouting. If the ants
have spread, additional supplies should be included in the estimates
for the second fall campaign; if not, the same quantity of supplies
AKGENTINE ANT IN THE UNITED STATES 37
should be ordered. The second campaign should be handled in the
same manner as the first.
If eradication is to be attempted, the summer following the second
fall campaign, a thorough scouting of the entire infested area should
be made to determine the exact status of the ants. If the ants are
rather generally distributed over the entire area and there are more
than one or two colonies per block, the infested area should be repoi-
soned as in the previous fall. If, however, the ants have been nearly
eradicated, it is only necessary to repoison within a radius of 50 feet
from each colony located. This should be done immediately and
again in the fall.
The following summer, if possible, the entire infested area should
be thoroughly scouted. If time or funds do not permit, then those
areas where colonies were previously found should be carefully ex-
amined. Of ten the ants have apparently been eradicated by the third
summer, but in such a case the area should not be released as free until
two additional annual scoutings have failed to disclose any ants.
The use of supplementary measures is often, practicable when the
abundance of ants has been reduced to a colony or less per block.
Such colonies can be dug out and the ants burned with a torch,
after which the ground should be well saturated with waste oil.
Even at the beginning of the work, in wooded areas it -is well to
burn out as many colonies as possible by setting fire to logs and
stumps and by gathering up all pieces of wood containing the ants
and throwing them into a general fire. Every precaution should be
taken to guard against forest fires.
The Argentine ant, Iridomyrmex humilis (Mayr), is a pest of no
little importance throughout the Southern States and in California.
It is especially troublesome as a house-infesting insect, being present
almost continuously throughout the year. Out of doors the ants feed
on the honeydew produced by scale insects, mealybugs, and aphids,
and do indirect damage to vegetation by fostering these insects. The
ants also steal seeds from seed beds, kill young poultry and birds in
their nests, destroy colonies of honeybees, and feed on the sap or fruit
juices from certain trees and plants, particularly citrus.
The wide and rapid spread of this ant since its introduction some-
time previous to 1891 has been accomplished chiefly by artificial
means, the railroads being the principal means of dispersion. Nat-
ural spread is due mainly to crawling, which varies from a few feet
to several hundred feet a year, but heavy rains, floods, etc., also play
an important role. Flight is a negligible factor in the spread of this
Argentine ants have been found in all types of soil and at eleva-
tions ranging from approximately sea level to nearly 4,000 feet.
They seem to be affected by strong winds, and by moisture conditions
in the soil. Although tropical insects, they can withstand more cold
than most of our native ants.
It is estimated that the Argentine ant occurs over an area of at least
4,000 square miles in the United States. California and Louisiana are
the most heavily infested States, and infestations also occur in Mis-
38 CIRCULAR 387, TJ. S. DEPARTMENT OF AGRICULTURE
sissippi, Alabama, Georgia, Texas, South Carolina, Arkansas, North
Carolina, Florida, Maryland, Tennessee, Arizona, Missouri, and
Illinois (States listed in order of decreasing size of infested area).
The size of the infestations varies from a single colony to areas con-
taining several hundred square miles. Although as yet the ants are
sporadically distributed over the States mentioned, except in Mis-
souri, Maryland, and Illinois, where the infestations are of the indoor
type, there is nothing to prevent them from occupying the entire area
within their present boundaries and also from spreading to additional
Efforts to control and eradicate the Argentine ant in Mississippi by
poisoning campa.igns have resulted in freeing 39 out of 245 infested
localities, and reducing the infestations in nearly all the others. The
method used in Mississippi is therefore described in some detail in this
circular. The ants can be controlled by one thorough campaign, and
by repeating the campaign each fall it is possible to eradicate them
in from 2 to 5 years. The method consists, in brief, in making careful
surveys of infested areas and then placing cups of sirup containing
sodium arsenite at proper intervals throughout these areas. Where
eradication is attempted, supplementary measures, such as burning
and oiling colonies, expedite the work, although these should not be
resorted to until the numbers have been greatly reduced. The cost of
eradicating ants should not be more than 3 cents per cup of poison,
or $3 to $6 per block.
(1) BAKBER, E. R,
1916. THE ARGENTINE ANT: DISTRIBUTION AND CONTROL IN THE UNITED
STATES. U. S. Dept. Agr. Bull. 377, 23 pp., lllus.
1920. THE ARGENTINE ANT AS A HOUSEHOLD PEST. II. S. Dept. Agr.
Farmers' Bull. 1101, 11 pp., illus.
(3) FOSTER, E.
1908. THE INTRODUCTION OF IRTDOMYRMEX HUMILIS (MAYR) INTO' NEW
ORLEANS. Jour. Econ. Ent. 1 : 289-293.
(4) HARKED, R. W.
1928 ARGENTINE ANTS ERADICATED AT SIX PLACES. MiSS. State Plant
Bd. Quart. 8 (3) : 10-11.
(5) and SMITH, M. R.
1922. ARGENTINE ANT CONTROL CAMPAIGNS IN MISSISSIPPI. Jolir. Econ.
Ent. 15: 261-2:64.
(6) HERBERT, F. B.
3932. EFFECT OF COLD STORAGE TEMPERATURES ON THE ARGENTINE ANT.
Jour. Econ. Ent. 25 : 832-833.
(7) HERTZER, L.
1930. RESPONSE OF THE ARGENTINE ANT (IRIDOMYRMEX HUMILIS MAYB) TO
EXTERNAL CONDITIONS. Ann. Ent. Soc. Amer. 23: 597-600.
(8) HORTON, J. R.
1918. THE ARGENTINE ANT IN" RELATION TO CITRrJS GROVES. U. S. Dept. Agr.
Bull. 647, 74 pp., illus.
1918. CONTROL OF THE ARGENTINE ANT IN ORANGE GROVES. U. S. Dept. Agr.
Farmers' Bull. 928, 20 pp., illus.
(10) NEWELL, W.
1908. NOTES OF THE HABITS OF THE ARGENTINE OR "NEW ORLEANS" ANT,
IRIDOMYRMEX HUMILIS MAYS. Jour. Econ. Ent. 1 : 21-34.
(11) and BAKBER, T. 0.
1913. THE ARGENTINE ANT. U. S. Dept. Agr., Bur. Ent. Bull. 122, 98 pp.,
ARGENTINE ANI IN THE UNITED STATES 39
(12) NICKELS, L. J.
1911. FIELD WORK IN THE CONTKOI, OF THE ARGENTINE ANT. JoUr Econ
Ent. 4: -358.
(13) RYAN, H. J.
1928. DISTRICT ARGENTINE. ANT CONTROL IN CITRUS ORCHARDS. Jour. Ecoll.
Ent. 21: 682-690.
(14) SMITH, M. R.
1919. OCCURRENCE OF THE ARGENTINA ANT AT RALEIGH, NORTH CAROLINA.
Jour. Econ. Ent. 12: 465.
1924. THE APPARENT ERADICATION OF THIS ARGENTINE ANT FROM FAYETTK,
MISSISSIPPI. (Sci. Note) Jour. Econ. Eut. 17: 603-604.
1927. THE AKGENTINE ANT AN ODOROUS SPECIES. (Sci. Note) Joill'. Eeoll.
Ent. 20: 646-647.
(17) WOGLTJM, R. S., and BORDEN, A. D.
1921. CONTROL OF THE ARGENTINE ANT IN CALIFORNIA CITRUS ORCHARDS.
D. S. Dept. Agr. Bull. 965, 43 pp., illus.
(18) and NEULS, J. D.
1917. THE COMMON MEALYBUG AND ITS CONTROL IN CALIFORNIA. U. S. Dept.
Agr. Farmers' Bull. 862, 16 pp., illus.
U. S. GOVERNMENT PRINTING OFFICE: 194
For sale by the Superintendent of Documents, Washington, D. C. - Price 5 cents