NATURA SLOVENIAE 21(2): 25-28 Prejeto / Received: 23. 8. 2019 
FIELD NOTE Sprejeto / Accepted: 27. 11. 2019 
 
Biotehniška fakulteta Univerze v Ljubljani in Nacionalni inštitut za biologijo, Ljubljana, 2019 
Two invasive ant species, 
Lasius neglectus Van Loon  
et al., 1990 and Tapinoma 
magnum Mayr, 1861 
(Hymenoptera: Formicidae), 
living in close proximity in 
coastal Slovenia 
 
Dve invazivni vrsti mravelj, Lasius 
neglectus Van Loon et al., 1990 in 
Tapinoma magnum Mayr, 1861 
(Hymenoptera: Formicidae), živeči v 
neposredni bližini v obalni Sloveniji 
 
Gregor BRAČKO,  
University of Ljubljana, Biotechnical Faculty, 
Department of Biology, Jamnikarjeva 101,  
SI-1000 Ljubljana, Slovenia;  
E-mail: gregor.bracko@bf.uni-lj.si 
 
Invasive species have been given much attention 
in the last decades and ants are no exception 
(e.g., McGlynn 1999, Holway et al. 2002, Lach & 
Hooper-Bùi 2009, Rabitsch 2011, Wittman 2014, 
Hoffmann et al. 2016). One of the most notorious 
ant species invading the European territory is 
Lasius neglectus Van Loon et al., 1990 (Fig. 1A). 
This species, probably originating from Asia Minor 
(Seifert 2000), was described from Budapest, 
Hungary (Van Loon et al. 1990), and is now 
reported from 16 European countries (Espadaler & 
Bernal 2018). Here it is mostly found in human-
modified habitats, ranging from purely urban 
habitats (e.g. in streets with heavy traffic) to city 
gardens, urban woods and semi-urban areas 
(Espadaler & Bernal 2018). It is reported on its 
negative effects on native arthropod fauna (Nagy 
et al. 2009). Less is known about Tapinoma 
magnum Mayr, 1861 (Fig. 2A). This species, 
previously also known under the name  
T. nigerrimum, is distributed in the Mediterranean 
area from NW Africa to Italy and is particularly 
abundant in open unstable or degraded areas with 
anthropogenic influence and a weakly developed 
tree layer (Seifert et al. 2017). Recently, it was 
reported to be artificially introduced to several 
cities in Germany, Belgium and the Netherlands, 
where it established permanent supercolonies and 
acts as a pest species with strong local impacts 
(Dekoninck et al. 2015, Noordijk 2016, Seifert  
et al. 2017). It shows the strongest invasive 
potential of all species of T. nigerrimum complex 
(Seifert et al. 2017). 
  
 
 
Figure 1. Lasius neglectus from Izola, Slovenia. A – Worker, lateral view (scale bar = 1 mm),  B – L. neglectus workers 
tending aphids on Quercus ilex in Izola park (photo: T. Delić – A, G. Bračko – B). 
Slika 1. Lasius neglectus iz Izole, Slovenija. A – Delavka, stranski pogled (merilce = 1 mm), B – Delavke L. neglectus 
negujejo listne uši na Quercus ilex v parku v Izoli (foto: T. Delić – A, G. Bračko – B). 
 
 
 
 Gregor BRAČKO: Two invasive ant species, Lasius neglectus and Tapinoma magnum ... / FIELD NOTE 
NATURA SLOVENIAE 21(2): 25-28 
26 
 
Figure 2. Tapinoma magnum from Izola, Slovenia. A – Worker, lateral view (scale bar = 1 mm), B – One of the many 
nests of T. magnum at Izola cemetery (with the open part of the nest pointed by the arrow) (photo: T. Delić – A,  
G. Bračko – B). 
Slika 2. Tapinoma magnum iz Izole, Slovenija. A – Delavka, stranski pogled (merilce = 1 mm), B – Eno izmed številnih 
mravljišč T. magnum na izolskem pokopališču (odprti del mravljišča je označen s puščico) (foto: T. Delić – A,  
G. Bračko – B). 
 
In 2008 and 2011, we found a colony of Tapinoma 
cf. nigerrimum next to the cemetery in the coastal 
town of Izola (SW Slovenia) (Bračko & Česnik 
2016). Applying the latest taxonomic revision of  
T. nigerrimum complex (Seifert et al. 2017), the 
colony was subsequently identified as T. magnum. 
The more detailed inspection of this part of the 
town in spring 2018 and 2019 revealed that  
T. magnum was spread over a much larger area.  
A big supercolony of this species was discovered, 
occupying the entire Izola cemetery (ca. two 
hectares) in NE part of the town (45°32.3'N, 
13°40.0'E, 3 m a.s.l.) and some smaller patches in 
its close vicinity (Fig. 3). During the inspection of 
the site, we discovered another invasive species, 
Lasius neglectus, which was spread over the urban 
park (ca. 1.5 hectare), situated just north of the 
cemetery (Fig. 3). The records of the two species 
from Izola are the only known for Slovenia. 
 
It looks that Tapinoma magnum found favourable 
habitat at Izola cemetery (Fig. 2B). The 
combination of stony ground and graveyard 
stones, some vegetation (grass, plants on graves, 
individual trees), and frequent watering of the 
plants could represent optimal conditions for this 
species. Tapinoma magnum acts very aggressively 
when its nests are disturbed. The visitors of the 
cemetery report on nuisances when in contact with 
these ants. In the vicinity of the cemetery,  
T. magnum nests can be found on lawns, along 
the paths and walls, but also on less disturbed 
sites, e.g. in the park west of the cemetery 
covered with some trees and shrubs. We assume 
that the species probably arrived to the cemetery 
area with the transport of plant and soil material 
for the needs of the cemetery. This way of 
transport is also responsible for the occurrence of 
T. magnum in the cities north of the Mediterranean 
area (Seifert et al. 2017). 
 
The urban park in Izola, colonised by L. neglectus, 
is covered with regularly cut lawn and individual 
pine and oak trees. The nest openings are 
concentrated mostly around trees and on the 
edges of lawn along the paths. The species is 
known for extensively tending honeydew 
producing aphids on trees and below ground (Paris 
& Espadaler 2009, Espadaler & Bernal 2018). In 
Izola, large columns of L. neglectus foraging 
workers, leading to/from their aphid colonies  
(Fig. 1B), can be spotted on every tree in the park. 
The human-mediated transport is the main way of 
spreading this species between sites (Espadaler  
et al. 2007). As in the case of T. magnum,  
L. neglectus probably established itself in Izola 
after being brought here with various plant and 
soil material. 
 
 Gregor BRAČKO: Two invasive ant species, Lasius neglectus and Tapinoma magnum ... / FIELD NOTE 
NATURA SLOVENIAE 21(2): 25-28 
27 
 
Figure 3. Izola map showing sites inhabited by the invasive ant species Lasius neglectus and Tapinoma magnum (base 
maps taken from www.geopedia.si and Atlas okolja, http://gis.arso.gov.si/atlasokolja). 
Slika 3. Karta Izole s prikazanimi mesti, poseljenimi z invazivnima vrstama mravelj Lasius neglectus in Tapinoma 
magnum (osnovne karte vzete iz www.geopedia.si in Atlasa okolja, http://gis.arso.gov.si/atlasokolja). 
  
In Izola, we can observe two supercolonies of two 
invasive ant species living in close proximity to 
each other, which is something relatively rare in 
the field (see Fig. 3). So far, L. neglectus and  
T. magnum have never been reported to come into 
close contact. There are some cases of 
encountering T. magnum and the notorious 
Argentine ant Linepithema humile (Mayr, 1868), 
where T. magnum was reported to limit the spread 
of L. humile (Seifert et al. 2017). In general, 
invasive ants are often highly aggressive, dominant 
competitors, trying to exclude other dominant 
colonies from their territory (Cerdá et al. 2013, 
Bertelsmeier et al. 2015). Currently, both species 
from Izola seem to occupy their optimal habitat  
(T. magnum the cemetery and L. neglectus the 
park) and prevent the other invasive species to 
spread into their territory. Along the path between 
the park and the cemetery, workers of both 
supercolonies can be observed, running away from 
each other when coming into contact. 
 
It would be interesting to monitor the situation in 
the area of the two invasive species in Izola in the 
next years, especially if their territories expand, 
and what the situation is to be like in the contact 
zone of both supercolonies. 
 
 
 Gregor BRAČKO: Two invasive ant species, Lasius neglectus and Tapinoma magnum ... / FIELD NOTE 
NATURA SLOVENIAE 21(2): 25-28 
28 
Acknowledgements 
 
I thank Teo Delić (University of Ljubljana, Slovenia) 
for his help in taking photos of the ants. 
 
 
References 
 
Bertelsmeier C., Avril A., Blight O., Confais A., Diez 
L., Jourdan H., Orivel J., Saint Germès N., 
Courchamp F. (2015): Different behavioural 
strategies among seven highly invasive ant 
species. Biol. Invasions 17: 2491-2503. 
Bračko G., Česnik L. (2016): First records of six ant 
species (Hymenoptera: Formicidae) for Slovenia. 
Nat. Slov. 18(2): 39-46. 
Cerdá X., Arnan X., Retana J. (2013): Is 
competition a significant hallmark of ant 
(Hymenoptera: Formicidae) ecology? Myrmecol. 
News 18: 131-147. 
Dekoninck W., Parmentier T., Seifert B. (2015): 
First records of a supercolonial species of the 
Tapinoma nigerrimum complex in Belgium. Bull. 
Soc. R. Belg. Entomol. 151: 206-209. 
Espadaler X., Bernal V. (2018): Lasius neglectus: a 
polygynous, sometimes invasive, ant. 
http://www.creaf.uab.es/xeg/Lasius/index.htm 
[accessed on August 2019]. 
Espadaler X., Tartally A., Schultz R., Seifert B., 
Nagy C. 2007: Regional trends and preliminary 
results on the local expansion rate in the 
invasive garden ant, Lasius neglectus 
(Hymenoptera, Formicidae). Insect. Soc. 54: 
293-301. 
Hoffmann B.D., Luque G.M., Bellard C., Holmes 
N.D., Donlan C.J. (2016): Improving invasive ant 
eradication as a conservation tool: A review. Biol. 
Conservation 198: 37-49. 
Holway D.A., Lach L., Suarez A.V., Tsutsui N.D., 
Case T.J. (2002): The causes and consequences 
of ant invasions. Annu. Rev. Ecol. Syst. 33:  
181-233. 
Lach L., Hooper-Bùi L.M. (2009): Consequences of 
ant invasions. In: Lach L., Parr C.L., Abbott K.L. 
(Eds.), Ant ecology, Oxford University Press, 
New York, pp. 261-286. 
McGlynn T.P. (1999): The worldwide transfer of 
ants: geographical distribution and ecological 
invasions. J. Biogeogr. 26: 535-548. 
Nagy C., Tartally A., Vilisics F., Merkl O., Szita E., 
Szél G., Podlussány A., Rédei D., Csősz S., 
Pozsgai G., Orosz A., Szövényi G., Markó V. 
(2009): Effects of the invasive garden ant, Lasius 
neglectus Van Loon, Boomsma & Andrásfalvy, 
1990 (Hymenoptera: Formicidae), on arthropod 
assemblages: pattern analyses in the type 
supercolony. Myrmecol. News 12: 171-181. 
Noordijk J. (2016): Leefwijze van Tapinoma 
nigerrimum (Hymenoptera: Formicidae), een 
nieuwe exotische mier in Nederland. Entomol. 
Ber. 76(3): 86-93. 
Paris C.I., Espadaler X. (2009): Honeydew 
collection by the invasive garden ant Lasius 
neglectus versus the native ant L. grandis. 
Arthropod-Plant Inte. 3: 75-85. 
Rabitsch W. (2011): The hitchhiker's guide to alien 
ant invasions. BioControl 56: 551-572. 
Seifert B. (2000): Rapid range expansion in Lasius 
neglectus (Hymenoptera, Formicidae) – an Asian 
invader swamps Europe. Mitt. Zool. Mus. Berl. 
47(2): 173-179. 
Seifert B., D'Eustacchio D., Kaufmann B., 
Centorame M., Lorite P., Modica M.V. (2017): 
Four species within the supercolonial ants of the 
Tapinoma nigerrimum complex revealed by 
integrative taxonomy (Hymenoptera: 
Formicidae). Myrmecol. News 24: 123-144. 
Van Loon A.J., Boomsma J.J., Andrásfalvy A. 
(1990): A new polygynous Lasius species 
(Hymenoptera; Formicidae) from Central Europe. 
Insect. Soc. 37: 348-362. 
Wittman S.E. (2014): Impacts of invasive ants on 
native ant communities (Hymenoptera: 
Formicidae). Myrmecol. News 19: 111-123.