Control of the turfgrass ant, Lasius neoniger, in Ohio - GCSAA

Control of the turfgrass ant,
Lasius neoniger, in Ohio
New tactics and products can help control a common golf course pest.
RESEARCH
David J. Shetlar, Ph.D.
A small ant, Lasius neoniger, has been a
nuisance on golf courses in an area extending
f rom New Ha m p s h i re across most of the
n o rthcentral United States. Re c e n t l y, this ant
has acquired the moniker “t u rfgrass ant,”
although the name is not officially re c o g n i ze d
by the Entomological Society of America.
The problem
The ant causes problems in high-maintenance
turf by building vo l c a n o - s h a p e d
mounds, 2 to 4 inches in diameter, which are
most evident on tees and putting greens. Eve n
though the mounds are flattened by mowe r s
each day, the soil covers the turf well enough
to cause dead patches. The sand and soil in
these mounds also dull mower blades rapidly.
The turfgrass ant is common in pasture s ,
fields and home lawns, but the mounds and
b u r rows in these areas generally go unnoticed.
Lasius neoniger is closely related to the
cornfield ant, which builds much larger
mounds in clean crop fields, where it tends
to protect aphids that attack various field
c rops. Ac ross No rth America, other species of
ants build similar mounds. As more and
m o re golf courses use sand-based tees and
g reens, and as standards for greens have risen,
the turfgrass ant and its re l a t i ves have
become a more significant problem. In fact,
it is a rare golf course that does not have some
species of ant throwing up small mounds on
some of the gre e n s .
Origins of this study
Ha r ry D. Niemczyk, Ph.D., intro d u c e d
me to the turfgrass ant by showing me his
f a vorite ant study site, a golf course in Clyd e ,
Oh i o. Built on ve ry sandy soils, this course
was almost entirely pockmarked with ant
mounds, from tee to green and across most
of the roughs. The owners have tried many
kinds of sprays to knock out this ant, but
Mounds built by the so-called turfgrass ant, Lasius neoniger, are a nuisance on golf courses across the country. This
mound is under construction.
with a limited budget, only temporary re l i e f
has been achieved. This course would have
been an excellent site for studying the biology
of the turfgrass ant, but studies had alre a d y
been initiated in the mid-1990s by St a n l e y
KEY points
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The so-called turfgrass ant is a nuisance
on golf courses from New England to the
northcentral United States.
Spring application of some insecticides
results in effective control throughout
the season.
When ant activity is extensive, baits
appear to be effective only when they
are applied at high rates.
Future research will test the usefulness of
fall insecticide applications in preventing
ants from returning in the spring.
Sw i e r, Ph.D. (Un i versity of New
Ha m p s h i re); Patricia Vittum, Ph . D .
( Un i versity of Connecticut); and Dan Po t t e r,
Ph.D. (Un i versity of Ke n t u c k y ) .
Life cycle
Little is known about L. neoniger, although
publications include a re p o rt on its nest stru c-
t u re (3) and some pre l i m i n a ry findings by
Werle and Vittum (4). The following comments
about its life cycle are a blend of personal
observations, published literature and
discussions with Sw i e r, Vittum and Po t t e r.
Habitat and diet
The turfgrass ant appears to pro d u c e
e x t e n s i ve colonies that consist of interc o n-
nected subcolonies. It is generally believe d
that there is one queen per colony. The queen
and workers apparently maintain chambers
at va rying depths in the soil in which eggs
and brood (larvae) are re a red. During the

RESEARCH
s u m m e r, additional chambers near the soil
s u rface are constructed, and each of these
chambers may have an opening to the outside
and an associated mound. T h e re f o re, a
colony may have one major opening and
n u m e rous satellite openings, each with its
associated mound of soil.
This ant seems to feed on all kinds of
food: fats, proteins and sugars (2).
T h e re f o re, the ants eat other insects (fats and
p roteins) and maintain honeyd ew - p ro d u c-
ing insects (sugar producers). A student of
Potter has recently confirmed a close association
between the turfgrass ant and ro o t -
infesting (soil) aphids (1).
Reproduction
An interesting paper published by a
USDA ant re s e a rcher in the 1930s (fro m
C l yde, Ohio) re p o rted that the ant seems to
p roduce one major brood after opening its
nests in the spring. The queen steps up egg
p roduction when food begins to flow into the
nest. The brood from this peak egg pro d u c-
tion develop rather slowly through Ma y, Ju n e
and Ju l y. New adult workers (all female)
begin to appear in Ju l y, and mound pro l i f e r-
ation increases dramatically. These work e r s
continue to collect food during the summer
months, apparently storing the re s e rves in the
nest in anticipation of lean periods. W h e n
colonies have matured, a considerable percentage
of the brood develops into a new
batch of winged re p ro d u c t i ves (queens and
d rones). The re p ro d u c t i ve cast consists of
The turfgrass ant is closely associated with root-infesting (soil) aphids.
much larger individuals that generally do not
m a t u re until late July and August.
On warm afternoons, often after re c e n t
rains, the new queens and drones swarm by
the thousands, and all colonies in an are a
commonly release these winged forms at the
same time. During these events, the ants can
become nuisances around lights at night.
New queens are about five times the body
weight of a worker or winged males. Like
most ants, the new queens and drones mate
while flying, and once the nuptial flight is
completed, the female seeks a new place to
build a chamber. Upon landing on the
g round, the queen chews off her wings and
builds a small chamber in the soil, often
t h rowing up a small mound of soil that may
be 3 ⁄8- to 1 ⁄2-inch in diameter. The chamber is
usually only an inch deep. Most queens die
b e f o re making chambers, and the ones that
successfully dig a burrow appear to die fro m
p redation or other causes within a week or
t w o. Queens that surv i ve in constru c t e d
chambers lay a small batch of eggs, and the
l a rvae that develop are fed regurgitated food
that appears to come from fat and wing muscle
reabsorbed by the queen.
Within six weeks, the small batch of new
w o rker ants (which are often half the size of
normal workers) break open the brood cham-
ANTS VS. INSECTICIDES, 2000
Rate
Active mounds/square yard (% reduction) ‡
Treatment † (pound ai/acre) 1 WAT 2 WAT 4 WAT 8 WAT 12 WAT 21 WAT
Talstar 0.2G 0.20 2.4 ef (87) 7.3 cd (46) 10.5 a (26) 10.1 ab (0) 10.8 a (0) 5.9 a (2)
Fipronil 0.0143G § 0.0125 12.3 ab (22) 10.9 a (19) 12.9 a (10) 7.5 bc (6) 4.8 bc (22) 2.1 b (65)
Fipronil 0.0143G 0.025 10.6 bc (37) 11.0 abc (18) 11.1 a (22) 6.4 c (20) 2.3 cd (63) 0.8 b (88)
Merit 75WP 0.40 11.1 abc (11) 8.9 bc (34) 5.8 b (60) 0.3 d (97) 0.1 d (98) 2.4 b (60)
Meridian 25WG 0.26 5.6 de (60) 3.0 de (78) 0.8 c (95) 0.1 d (98) 0.1 d (98) 2.0 b (67)
Meridian 25WG + 0.26
Scimitar 0.88GC 0.06 0.4 f (98) 0.0 e (100) 1.4 bc (90) 0.5 d (94) 0.6 d (90) 1.3 b (79)
Check 14.8 a 13.4 ab 14.3 a 8.0 bc 6.4 b 6.0 a
†
‡
Treatments applied May 17,2000,to plots 10 by 15 feet,replicated four times.No irrigation after treatment.
Data taken May 25,June 1,June 15,July13,Aug.10 and Oct.12,based on the same central 2 square yard area observed each time within each plot.Means followed by the same letter
are not significantly different.
§
Fipronil was an experimental insecticide at the time of this treatment.The current product with fipronil as the active ingredient is Firestar.
Data are shown for the efficacy of insecticides in controlling ant mounds of Lasius neoniger (Emery) one to 21 weeks after treatment (WAT) on a golf course fairway at
Crockett’s Green Hills Golf Course,Clyde,Ohio.Data are for the 2000 season.

e r, forage for food and help feed another
small brood. By this time, winter has arrive d
and activity in new as well as established
colonies ceases. Established colonies and new
colonies that surv i ve the winter resume activity
from late April into early May in Oh i o.
Ant control
Suspecting this kind of life cyc l e ,
Niemczyk has stated that the time to contro l
this ant is when the mounds first appear in
the spring. At this time, the colonies are at
their weakest point: low on food re s e rve s ,
with older workers and few new brood. An
application of chlorpyrifos (Dursban) within
a week of mound appearance in the spring
has often provided four to six weeks of
mound suppression. Applications made later
in the season usually suppress mounds for
only two to three we e k s .
In studies in the 1990s, Niemczyk and I
found that several of the pry re t h roid insecticides
— cyfluthrin (Tempo), bifenthrin
(Talstar), deltamethrin (De l t a g a rd), lambdacyhalothrin
(Scimitar) — provide the same
l e vel of control as chlorpyrifos, especially if
they are used when mounds first appear.
Later in the season, do not expect more than
two weeks of mound suppre s s i o n .
When imidacloprid (Merit), halofenozide
(MACH2), fipronil (Chipco Choice),
and thiamethoxam (Meridian — not registered
for turfgrass usage) were being developed,
Niemczyk and I began trials to
evaluate how these insecticides might influence
mound building by L. neoniger over an
entire season. We have applied these materials,
at first mound formation in the
RESEARCH
spring, for nearly five seasons and the re s u l t s
have been fairly consistent.
Halofenozide seems to have no measurable
affect on the turfgrass ant. Fi p ro n i l
(either as sprays or the recently re g i s t e re d
bait) tends to knock down the mounds after
two to three weeks, and often the mounds do
not reappear for six to 10 months.
Imidacloprid seems to act ve ry slow l y, with
mound-building suppression not occurring
until four to six weeks after the initial application.
Howe ve r, once it occurs, mound supp
ression tends to last for the rest of the
season, and perhaps into the next season.
T h i a m e t h oxam has knocked down the ant
activity in only two to three weeks consistently;
ants usually do not return for the re s t
of the season.
Applications of imidacloprid and fipro n i l
ANTS VS. INSECTICIDES, 2001
Rate Active mounds/square yard (% reduction) ‡
Treatment † (pound ai/acre) 1 WAT 2 WAT 4 WAT 6 WAT 10 WAT 16 WAT
Talstar 0.2G 0.20 3.84 a (35) 5.8 a (25) 5.1 a (0) 7.4 b (0) 6.4 b (0) 4.1 b (6)
Fipronil 0.0143G § 0.0125 6.0 a (0) 8.3 ab (0) 6.0 a (0) 6.4 b (6) 6.6 b (0) 2.0 ab (55)
Fipronil 0.0143G 0.025 7.9 ab (0) 7.1 a (7) 6.0 a (0) 6.4 b (20) 3.8 ab (32) 0.8 a (83)
Merit 75WP 0.40 11.8 a (0) 13.75 (0) 12.3 b (0) 10.38 b (97) 5.3 b (5) 2.8 ab (37)
Meridian 0.33G 0.26 5.4 a (7) 5.8 a (25) 3.4 a (31) 1.0 a (84) 0.4 a (93) 1.3 a (71)
Check 5.8 a 7.6 ab 4.9 a 6.3 b 5.5 b 4.4 b
†
Treatments applied May 7,2000,to plots 10 by 15 feet replicated four times.No post-treatment irrigation.
‡
Data taken May 14,May 21,June 18,July 2,July 30,and Sept.10 based on the same central 2 square yard area observed each time within each plot.Means followed by the same letter
are not significantly different.
§
Fipronil was an experimental insecticide at the time of this treatment.The current product with fipronil as the active ingredient is Firestar.
Data are shown for the efficacy of insecticides in controlling ant mounds of Lasius neoniger (Emery) one to 16 weeks after treatment (WAT) on a golf course fairway at
Crockett’s Green Hills Golf Course,Clyde,Ohio.Data are for the 2001 season.
FIRESTAR AND MERIDIAN VS. ANTS, 2002
Rate Active mounds/4 square yards (% reduction) ‡
Treatment † (pound ai/acre) 1 WAT 2 WAT 3 WAT 4 WAT 5 WAT 6 WAT 8 WAT
Firestar 0.00015 B 10.0 8.5 bc (79) 6.5 a (53) 2.5 a (38) 6.8 bcd (63) 8.5 abc (53) 7.5 a (3) 13.8 ab (42)
Firestar 0.00015 B 15.0 11.0 bc (73) 6.5 a (53) 2.5 a (38) 6.5 bcd (64) 4.8 bc (74) 4.0 a (48) 9.8 ab (59)
Firestar 0.00015 B 30.0 5.5 c (87) 3.8 a (73) 1.8 a (56) 2.0 cd (89) 1.5 bc (93) 2.0 b (74) 5.3 b (78)
Meridian 0.33 G 0.26 11.0 bc (73) 2.5 a (82) 0.3 a (94) 0.5 d (97) 0.3 c (99) 0.0 b (100) 0.0 b (100)
Check 41.3 a 13.8 a 4.0 a 18.3 a 18.3 a 7.8 a 23.8 a
†
Treatments applied June 24,2002,to plots 15 by 15 feet,replicated four times.No irrigation after treatment.
‡
Data taken July 1,July 8,July 15,July 22,July 29,Aug.5 and Aug.19,based on the same central 4-square-yard area observed each time within each plot.Means followed by the same
letter are not significantly different.
Data are shown for the efficacy of treatments with Firestar bait and Meridian in controlling ant mounds of Lasius neoniger (Emery) one to 8 weeks after treatment (WAT) on
a golf course fairway at Crockett’s Green Hills Golf Course,Clyde,Ohio.Data are for the 2002 season.

RESEARCH
formulations after the workers have been foraging
for several weeks have resulted in much
less suppression later in the season. Howe ve r,
f i p ronil baits have significantly reduced ant
mound construction, even in midseason.
I believe that their unique modes of action
explain how imidacloprid and fipronil work .
Imidacloprid has been shown to change normal
insect behavior, and an early application
may somehow disrupt the rearing of the
b rood, which would explain the action
appearing four to six weeks after application.
Fi p ronil is a slow-acting poison and is apparently
picked up by the workers, taken back to
the colony and fed to other workers, bro o d
and even the queen before they know that
they have been poisoned.
Ant baits
Because Potter and his students (1)
found ve ry good control of L. neoniger w i t h
h ydramethylnon bait (Ma x f o rce), we
included it in our studies and compared it
with the recently re g i s t e red fipronil ant bait
(Firestar). At label rates of Maxforce, ant
mound suppression was minimal, but this
result was similar to results achieved with the
lower rates of Firestar. In fact, high rates of
both baits were required to get significant
reductions in ant-mounding activity.
I believe that when ve ry high populations
of the turfgrass ant are present, the established
baiting rates are not sufficient to supply
enough active ingredient to the biomass of
ants invo l ved. In these situations, the baits
must be reapplied on a regular basis (possibly
e ve ry two weeks, for three applications), or the
early-spring control tactic will have to be used.
W h e re only a few mounds appear on a golf
g reen or tee, application of either bait over a
small area should knock out the ants.
Se verity of the pro b l e m
Cu r re n t l y, my recommendations for ant
c o n t rol depend on the severity of the pro b l e m .
For a few occasional mounds, an early application
of a pyre t h roid or chlorpyrifos (which is
still available for use on golf courses) followe d
with subsequent applications of baits if the
mounds should return with either hyd r a -
methylnon or fipronil-based products should
p rovide satisfactory results. On courses where
large populations of this ant cause problems on
g reens, tees and fairways re g u l a r l y, an early
application of imidacloprid or fipronil should
eliminate ant activity for much of the season.
We have also learned quite a bit about
baits. As has been shown, when baits are used
to control fire ants, the turfgrass ant can be
rather finicky about the quality of the bait. If
baits are used, be sure to apply them to dry
turf when rainfall is not likely to occur and
irrigation can be withheld for about two days.
Ap p a re n t l y, rain and irrigation render most of
the baits unattractive.
Future research
Di f f e rent control tactics for this ant are
being considered, including application of imidacloprid,
thiamethoxam or fipronil when the
n ew queens establish colonies in Se p t e m b e r.
The thought behind this method is that the ant
colonies would take in enough material during
the fall to lower their winter surv i val, and ant
colonies eliminated in the fall and winter
should not reappear the following spring.
Acknowledgments
We thank Bob Crockett, owner of Crockett’s Green
Hills Golf Course, C ly d e ,O h i o , for allowing us to use his golf
course in our studies.
References
1. L o p e z , R ., D . W. Held and D.A. Po t t e r. 2000 .
Management of a mound-building ant, Lasius
neoniger Emery, on golf putting greens using
delayed action baits of fipronil. Crop Science 40:
511-517.
2. Traniello, T.F.A.1983.Social organization and foraging
success of Lasius neoniger (Hymenoptera:
Formicidae):behavioral and ecological aspects of
recruitment communication. Oecologica 59:94-
100.
3. Wang, D., K. McSweeney, B. Lowery and J.M.
Norman. 1995. Nest structure of the ant Lasius
neoniger Emery and its implications on soil modification.
Geoderma 66:259-272.
4. Werle, S.F., and P.J. Vittum. 1999. The turfgrass
a n t : a necessary nuisance Golf Course
Management 67:49-52.
David J.Shetlar, Ph.D.(shetlar.1@osu.edu),is an associate
professor of entomology at Ohio State University,
Columbus.
CURATIVE TREATMENTS, 2001
Rate (pound
Active mounds/square yard (% reduction) ‡
Treatment † ai/acre) 1 WAT 2 WAT 4 WAT 6 WAT 8 WAT 11 WAT
Meridian 25WG 0.26 5.63 bc (29) 4.6 ab (53) 2.2 a (69) 1.9 a (74) 3.6 a (67) 3.2 a (57)
Tempo Ultra SC 0.07 9.44 c (0) 11.8 c (0) 10.1 cd (0) 8.0 c (0) 13.7 c (0) 9.1 cd (0)
Dursban Pro 2EC 1.5 1.5 a (81) 3.2 a (68) 5.8 abc(18) 5.6 abc(22) 9.6 bc (15) 7.9 bcd (0)
DeltaGard 0.42F 0.13 9.0 c (0) 10.4 c (0) 11.0 d (0) 6.6 bc (8) 12.8 c (0) 9.0 cd (0)
Talstar 0.67F 0.20 3.3 ab (58) 10.0 c (0) 3.4 a (31) 9.1 c (0) 12.6 c (0) 11.3 d (0)
Firestar Bait 0.000225 5.7 bc (28) 8.8 bc (11) 9.3 cd (0) 6.9 bc (4) 10.9 bc (4) 8.5 cd (0)
Firestar Bait 0.00225 1.25 a (84) 2.2 a (78) 4.0 ab (44) 3.6 ab (50) 6.8 ab (41) 4.7 ab (38
Check 7.9 a 9.8 c 7.1 d 7.2 bc 11.4 bc 7.4 bc
†
Treatments applied June 18,2001,to plots 10 by 15 feet replicated four times.No irrigation after treatment.
‡
Data taken June 25,July 2,July 16,July 30,Aug.13 and Sept.10,based on the same central 2-square-yard area observed each time within each plot.Means followed by the same letter
are not significantly different.
Data are shown for the efficacy of insecticides in controlling ant mounds of Lasius neoniger (Emery) one to 11 weeks after treatment (WAT) on a golf course fairway at
Crockett’s Green Hills Golf Course,Clyde,Ohio.Data are for the 2001 season.