The term myrmecophile means ‘ant lover’, from the Greek ‘myrmex’ (ant) and ‘philos’ (loving). In the most general sense, any organism that is dependent on ants at least during part of its lifecycle is a myrmecophile. This definition encompasses plants that attract ants with food bodies or extrafloral nectaries, homopterans such as aphids, membracids, and scale insects that provide ants with honeydew, as well as fungi and bacteria that are cultivated or housed by some ants.Organismic and Evolutionary Biolog

Kronauer, Daniel J.C.

Pierce, Naomi E.

Current Biology

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comes as no surprise that ant colonies 
are such a desirable place to call home 
for a variety of organisms.
How diverse are myrmecophiles? 
In 1894, Erich Wasmann, an Austrian 
Jesuit priest and one of the pioneering 
students of myrmecophiles, 
documented 1,177 ant guests, and the 
list has grown at an astonishing rate 
ever since. Myrmecophily has  
evolved independently in a large 
number of taxonomic groups, including 
flies (Figure 1A), beetles (Figure 1B 
and C), crickets (Figure 1D), butterflies 
(Figure 1E), bristletails, millipedes, 
isopods, snails, mites, aphids, scale 
insects, wasps, and even snakes. The 
taxonomically most diverse groups 
of myrmecophiles are mites and 
staphylinid beetles.
Ant species with the largest colonies 
generally harbor the highest diversity 
of myrmecophiles, while most species 
with small colonies rarely entertain 
guests. The reasons for this pattern 
are similar to those governing the 
dynamics of island biogeography: large 
colonies provide a larger variety of 
microhabitats and can sustain larger 
and more stable populations of guests 
over longer time periods.
A particularly striking diversity of 
myrmecophiles is associated with 
army ants (Figure 1A–C). Colonies of 
army ants contain between tens of 
thousands and millions of workers, 
which form large raiding parties that 
overwhelm and kill other arthropods. 
In a recent overview, Rettenmeyer et al. 
(2010) listed over 300 animals that 
depend on a single army ant species, 
Eciton burchellii. Most of these species 
are inquilines, including mites, beetles, 
scuttle flies, and bristletails. Army ant 
myrmecophiles are not only extremely 
diverse taxonomically, they are also 
abundant. One study estimated that 
an average Eciton burchellii colony 
harbors 20,000 mites. The nomadic 
colonies of army ants really are 
travelling circuses.
What are the interactions between 
myrmecophiles and ants? Different 
myrmecophiles interact with the ants in 
different ways, ranging from parasitism 
to mutualism. Some prey on the ants or 
their brood, some are ectoparasites or 
endoparasites, some are commensals 
and some are mutualists, providing 
the ants with beneficial services in 
exchange for safe housing. Some 
myrmecophiles are spectacular mimics 
Myrmecophiles
Daniel J.C. Kronauer  
and Naomi E. Pierce
What are myrmecophiles? The term 
myrmecophile means ‘ant lover’, from 
the Greek ‘myrmex’ (ant) and ‘philos’ 
(loving). In the most general sense, 
any organism that is dependent on 
ants at least during part of its lifecycle 
is a myrmecophile. This definition 
encompasses plants that attract 
ants with food bodies or extrafloral 
nectaries, homopterans such as 
aphids, membracids, and scale insects 
that provide ants with honeydew, as 
well as fungi and bacteria that are 
cultivated or housed by some ants. The 
majority of myrmecophiles, however, 
are insects and other arthropods that 
benefit from the vast resources an ant 
colony provides in one way or the other. 
Here we limit our discussion to only 
those myrmecophiles that are animals 
living inside ant nests, the so-called ant 
guests, or inquilines.
What is so special about ant nests? 
Edward O. Wilson eloquently described 
large colonies of ants, such as  
leaf-cutting ants, army ants, or wood 
ants, as factories constructed inside 
fortresses. In fact, such colonies 
are extremely well defended by the 
ants, so from the perspective of a 
myrmecophile, they provide ‘enemy 
free space’ in an area effectively 
devoid of predators — that is, once the 
myrmecophile has figured out how to 
circumvent aggression from the ants 
themselves. Furthermore, ant nests 
provide homeostatic environments 
where temperature and humidity are 
controlled by sophisticated ventilation 
systems, sheltering the queen and the 
rest of the colony from the elements. 
Socially organized with a highly 
effective division of labor, ants have 
become ecologically dominant in most 
terrestrial ecosystems, where they 
successfully compete for resources as 
scavengers, predators, herbivores, and 
mutualists. This means that ant nests 
are an abundant niche where food 
is often plentiful. Furthermore, these 
fortresses are typically stable and long-
lived, as colonies of many ant species 
can persist for several decades. It thus 
Quick guide
Figure 1. Exemplar myrmecophiles.
(A) Adult female scuttle fly Vestigipoda longi-
seta among the brood of its army ant host, 
Aenictus spec. (photo courtesy of Munetoshi 
Maruyama). (B) Two limuloid Cephaloplectus 
beetles (arrow) hitching a ride on a Pachy-
condyla prey ant being carried by two Eciton 
vagans army ant workers. (C) A staphylinid 
beetle of the genus Ecitophya runs in the raid-
ing column of the army ant Eciton burchellii 
(just below the major worker). (D) The cricket 
Myrmecophilus albicinctus in a nest of the 
yellow crazy ant Anoplolepis gracilipes. (E) 
Workers of the host ant Myrmica rubra are 
tending pupae of the alcon blue butterfly, 
Maculinea alcon. (Photos B–E by Daniel 
Kronauer.)
Magazine
R209
of ant larvae (Figure 1A), the ant version 
of a cuckoo. Less integrated guests, 
on the other hand, often simply avoid 
direct contact with the ants and spend 
most of the time in the periphery of the 
nest.
The effect a myrmecophile has on 
its host ants often correlates with the 
level of integration into the host colony, 
with more detrimental species typically 
being less well integrated. This is either 
because myrmecophiles become less 
virulent as they evolve to integrate into 
the ant society, or because the ants 
recognize and attack more harmful 
myrmecophiles.
Wasmann originally devised a 
scheme to classify myrmecophiles on 
the basis of their level of integration 
and their interaction with the 
ants. Although this classification 
has heuristic value in describing 
interactions, given the great variety 
of myrmecophilic lifestyles, many 
species do not naturally fit into one of 
his rather rigid categories. It has also 
become apparent that parasitism and 
mutualism only represent the extremes 
of a continuum, and that the outcome 
of any given interaction is dynamic and 
depends on a variety of parameters. 
Accordingly, Wasmann’s original 
classification is less used today. 
The level of integration into the host 
colony can also correlate with the 
level of specialization on a particular 
ant host. For example, ant crickets 
of the genus Myrmecophilus can be 
specialists or generalists with respect 
to their ant host species. M. albicinctus 
is a specialist that exclusively lives 
in nests of the yellow crazy ant, 
Anoplolepis gracilipes (Figure 1D). 
The crickets freely walk around the 
ants without being attacked, and 
they engage in intimate behavioral 
interactions with the ants, such as 
trophallaxis, the sharing of liquid food 
from mouth to mouth. The crickets 
cannot survive when removed from the 
ant colony and they are attacked and 
killed when introduced into the nests 
of other ants. M. formosanus, on the 
other hand, occurs with a wide range 
of ant host species. The crickets feed 
independently, escape the frequently 
attacking ants by swift movements, and 
readily survive outside of ant colonies.
How do myrmecophiles integrate into 
ant societies? Ants can be fierce hosts 
and myrmecophiles have adopted a 
variety of tactics to evade or avoid 
ant attack. An ant colony is a world of 
odors, and the prime mechanism to fit 
in seamlessly is to smell like the host. 
Ants use a colony-specific, complex 
profile of cuticular hydrocarbons to 
tell nestmates from foreigners. Many 
myrmecophiles acquire this signature 
by grooming the ants and rubbing 
against the nest material until they 
are chemically camouflaged. Some 
myrmecophiles, like the staphylinid 
beetle Atemeles pubicollis, produce 
specific chemicals that seem to mimic 
the brood pheromone of their hosts, 
and trick the ants into adopting the 
beetles as one of their own. The beetles 
also have a second gland that releases 
an ant appeasement substance used to 
suppress aggressive behavior. 
Behavioral mimics are also common 
when it comes to soliciting food from 
the ants, and some species, like 
Myrmecophilus ant crickets, adjust 
their movements to match those of 
their host species. Recently it has 
also been suggested that larvae and 
pupae of Maculinea butterflies mimic 
the stridulation calls of queen ants 
to be more attractive to workers. In 
terms of morphological adaptations, 
many ant guests have short or hidden 
appendages that are difficult to 
snag, and a recurrent theme among 
myrmecophiles is a smooth and 
teardrop shaped (‘limuloid’) body form, 
which probably slips easily through the 
grip of the ants’ mandibles (Figure 1B).
Some ant guests also strikingly 
resemble their ant hosts in overall 
body shape and coloration, a 
phenomenon known as Wasmannian 
mimicry. While Wasmann suggested 
that this form of mimicry is mainly 
adaptive to deceive the ants 
themselves, others have argued 
that it has most likely evolved in 
response to potential predators, such 
as birds, which would otherwise be 
able to pick out tasty myrmecophiles 
among unpalatable ants. In this case 
Wasmannian mimicry would not be 
much different from Batesian mimicry. 
A classic example of Wasmannian 
mimicry is the staphylinid beetle 
Ecitophya, which lives in the colonies 
of neotropical army ants (Figure 1C).
What are the life cycles of 
myrmecophiles? Their life cycles 
are as diverse as the myrmecophiles 
themselves, ranging from simple to 
complex. Ant crickets, for example, 
reproduce and spend their entire life 
inside the ant colonies. They probably 
disperse to other host nests simply by 
walking along the ants’ foraging trails. 
Other myrmecophiles have complex 
life cycles that enable them to track 
the phenology of their hosts. The alcon 
blue butterfly, Maculinea alcon, for 
example, deposits eggs on gentian 
flowers in the summer. The caterpillars 
initially feed inside the flower before 
eventually letting themselves down 
to the ground. If they are lucky, they 
are picked up by a Myrmica ant and 
carried back to the nest. Here they are 
assiduously fed by the ant workers, 
which are unable to discriminate the 
parasites in their midst. Like several 
other myrmecophilous butterflies, 
M. alcon has an unusually long period 
of larval development, with larvae 
overwintering inside the ant nest. In 
early summer of the following year, the 
larvae pupate (Figure 1E) and about a 
month later the adult butterflies emerge. 
The butterflies then rush to leave their 
foster parents behind, in an effort not to 
be attacked and torn to pieces. These 
are only a few well-studied examples. 
For many myrmecophiles, however, the 
information on life cycle and natural 
history is still very incomplete.
Where can I find out more?
Akino, T. (2008). Chemical strategies to deal 
with ants: a review of mimicry, camouflage, 
propaganda, and phytomimesis by ants 
(Hymenoptera: Formicidae) and other 
arthropods. Myrmecol. News 11, 173–181.
Hölldobler, B., and Wilson, E.O. (1990). The Ants. 
(Cambridge, MA: Harvard University Press.)
Kistner, D.H. (1982). The social insects’ bestiary.  
In Social Insects. Vol. 3. H.R. Hermann, ed.  
(New York: Academic Press), pp. 1–244.
Komatsu, T., Maruyama, M., and Itino, T. (2009). 
Behavioral differences between two ant cricket 
species in Nansei Islands: host-specialist versus 
host-generalist. Insect. Soc. 56, 389–396.
Nash, D.R., and Boomsma, J.J. (2008). 
Communication between hosts and social 
parasites. In Sociobiology of Communication: 
An Interdisciplinary Perspective. P. d’Ettorre and 
D. P. Hughes, eds. (Oxford: Oxford University 
Press), pp. 55–79.
Pierce, N.E., Braby, M.F., Heath, A., Lohman, D.J., 
Mathew, J., Rand, D.B., and Travassos, M.A. (2002). 
The ecology and evolution of ant association 
in the Lycaenidae (Lepidoptera). Annu. Rev. 
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and Berghoff, S.M. (2010). The largest animal 
association centered on one species: the 
army ant Eciton burchellii and its more than 
300 associates. Insect. Soc., online early DOI: 
10.1007/s00040-010-0128-8.
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(2005). Specializations and host associations of 
social parasites of ants. In Insect Evolutionary 
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Witte, V. (2010). Differential host defense against 
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DOI: 10.1007/s10682-010-9420-3.
Museum of Comparative Zoology,  
Harvard University, 26 Oxford Street, 
Cambridge, MA 02138, USA.  
E-mail: dkron@fas.harvard.edu


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