Foraging The genus
Myrmecia is among the most primitive of all known living ants, and ants of the genus are considered specialist predators. Unlike most ants, workers are solitary hunters, and do not lay
pheromone trails; nor do they recruit others to food.
Tandem running does not occur, and workers carrying other workers as a method of transportation is rare or awkwardly executed. Although
Myrmecia is not known to lay pheromone trails to food,
M. gulosa is capable of inducing territorial alarm using pheromones while
M. pilosula can attack
en masse, suggesting these ants can also induce alarm pheromones.
M. gulosa induces territorial alarm behaviour using pheromones from three sources; an alerting substance from the rectal sac, a pheromone found in the
Dufour's gland, and an attack pheromone from the mandibular gland. Despite
Myrmecia ants being among the most primitive ants, they exhibit some behaviours considered "advanced"; adults will sometimes groom each other and the brood, and distinct nest odors exist for each colony. Most species are
diurnal, and forage on the ground or onto low vegetation in search of food, but a few are
nocturnal and only forage at night. Most
Myrmecia ants are active during the warmer months, and are
dormant during winter. However,
M. pyriformis is a nocturnal species that is active throughout the whole year.
M. pyriformis also has a unique foraging schedule; 65% of individuals who went out to forage left the nest in 40–60 minutes, while 60% of workers would return to the nest in the same duration of time at dusk. Foraging workers rely on landmarks for navigation back home. If displaced a short distance, they will scan their surroundings, and then rapidly move in the direction of the nest.
M. vindex ants carry dead nest-mates out of their nests and place them on refuse piles, a behaviour known as
necrophoresis.
Pollination While pollination by ants is somewhat rare, several
Myrmecia species have been observed pollinating flowers. For example, the orchid
Leporella fimbriata is a
myrmecophyte which can only be pollinated by the winged male ant
M. urens. Pollination of this orchid usually occurs between April and June during warm afternoons, and may take several days until the short-lived males all die. The flower mimics
M. urens queens, so the males move from flower to flower in an attempt to copulate with it.
M. nigrocincta workers have been recorded visiting flowers of
Eucalyptus regnans and
Senna acclinis, and are considered a potential pollination vector for
E. regnans trees. Although
Senna acclinis is self-compatible, the inability of
M. nigrocincta to appropriately release
pollen would restrict its capacity to effect
pollination. Although
pollinia are often seen in the ants' jaw, they have a habit of cleaning their mandibles on the leaves and stems of nectar-rich plants before moving on, preventing
pollen exchange.
Diet '' Despite their ferocity, adults are
nectarivores, consuming
honeydew (a sweet, sticky liquid found on leaves, deposited from various insects), nectar, and other sweet substances. Young ants are rarely fed food regurgitated by adults. Adult workers prey on a variety of insects and arthropods, such as beetles, caterpillars, earwigs,
Ithone fusca,
Perga sawflies, and spiders. Other prey include invertebrates such as bees, cockroaches, crickets, wasps and other ants; in particular, workers prey on
Orthocrema ants (a subgenus of
Crematogaster) and
Camponotus, although this is risky since these ants are able to call for help through chemical signals. Slaters, earthworms, scale insects, frogs, lizards, grass seeds, possum feces and kangaroo feces are also collected as food. Flies such as the
housefly and
blowfly are consumed. Some species, such as
M. pilosula, will only attack small fly species and ignore larger ones. Nests of the
social spider Delena cancerides are often invaded by
M. pyriformis ants, and nests once housing these spiders are filled with debris such as twigs and leaves by the workers, rendering them useless. These "
scorched earth" tactics prevent the spiders competing with the ants.
M. gulosa attacks
Christmas beetles, but workers later bury them.
Myrmecia is one of the very few genera where the workers lay
trophic eggs, or infertile eggs laid as food for viable offspring. Workers laying trophic eggs have only been reported in two species; these species are
M. forceps and
M. gulosa. Depending on the species, colonies specialise in
trophallaxis; queens and larvae eat eggs that are laid by worker individuals, but the workers do not feed on eggs. while avoiding the potent sting of the adults, which it is vulnerable to. The
short-beaked echidna (
Tachyglossus aculeatus) also eats the eggs and larvae.
Nymphs of the assassin bug species
Ptilocnemus lemur lure these ants to themselves by trying to make the ant sting them, by waving its hind legs around to attract a potential prey item. Body remains of
Myrmecia have been found in the stomach contents of the
eastern yellow robin (Eopsaltria australis). The
Australian magpie (
Gymnorhina tibicen), the
black currawong (
Strepera versicolor), and the
white-winged chough (
Corcorax melanorhamphos) prey on these ants, but few are successfully taken. The host association between
Myrmecia and
eucharitid wasps began several million years ago;
M. forficata larvae are the
host to
Austeucharis myrmeciae, being the first recorded eucharitid
parasitoid of an ant, and
Austeucharis fasciiventris is a parasitoid to
M. gulosa pupae.
M. pilosula is affected by a
gregarines parasite that changes an ant's colour from their typical black appearance to brown. This was discovered when brown workers were dissected and found to have
gregarinasina spores, while black workers showed no spores. Other parasites include
Beauveria bassiana,
Purpureocillium lilacinum (formerly known as
Paecilomyces lilacinus),
Chalcura affinis,
Tricoryna wasps, and various
mermithid nematodes.
M. hirsuta and
M. inquilina are the only known species in this genus that are
inquilines and live in other
Myrmecia colonies. An
M. inquilina queen has been found in an
M. vindex colony.
Myrmecia is a larval attendant to the butterfly
Theclinesthes serpentata (saltbush blue), while some species, particularly
M. nigrocincta,
enslave other ant species, notably those in the genus
Leptomyrmex.
M. nigriceps ants are able to enter another colony of the same species without being attacked, as they may be unable to recognise alien conspecifics, nor do they try to distinguish nestmates from ants of another colony.
Formicoxenus provancheri and
M. brevinoda share a form of
symbiotic relationship known as xenobiosis, where one species of ant will live with another and raise their young separately, with
M. brevinoda being the host.
Solenopsis may sometimes nest in
Myrmecia colonies, as a single colony was found to have three or four
Solenopsis nests inside.
Lagria beetles and
rove beetles in the genus
Heterothops dwell inside colonies and
skinks and frogs have also been found living unharmed within
Myrmecia nests.
Metacrinia nichollsi, for example, has been reported living inside
M. regularis colonies.
Life cycle Like other ants,
Myrmecia ants begin as an
egg. If the egg is fertilised, the ant becomes a
diploid female; if not, it becomes a
haploid male. They develop through
complete metamorphosis, meaning that they pass through larval and pupal stages before emerging as adults. During the process of founding a colony, as many as four queens cooperate with each other to find a suitable nesting ground, but after the first generation of workers is born, they fight each other until one queen is left alive. However, occasional colonies are known to have as many as six queens coexisting peacefully in the presence of workers. A queen searches for a suitable nest site to establish her colony, and excavates a small chamber in the soil or under logs and rocks, where she takes care of her young. A queen also hunts for prey instead of staying in her nest, a behaviour known as claustral colony founding. Although queens do provide sufficient amounts of food to feed their larvae, the first workers are "nanitics" (or minims), smaller than the smallest workers encountered in older developed colonies. Several species do not have any worker caste, and solitary queens will raid a colony, kill the residing queen, and take over the colony. The larvae are capable of crawling short distances without the assistance of adult workers, and workers will cover the larvae in dirt to help them spin into a cocoon. If cocoons are isolated from a colony, they are capable of shedding their skins before hatching, allowing themselves to advance to full
pigmentation. Sometimes, a newborn can emerge from its pupa without the assistance of other ants.
Myrmecia lifespans vary in each species, but their longevity is greater than many ant genera:
M. nigrocincta and
M. pilosula have a lifespan of one year, while
M. nigriceps workers can live up to 2.2 years. The oldest recorded worker was a
M. vindex, living up to 2.6 years. If a colony is deprived of workers, queens are able to revert to colony-founding behaviours until a sustainable workforce emerges. A colony may also emigrate to a new nesting spot altogether.
Reproduction Winged, virgin queens and males, known as
alates, appear in colonies during January, before their
nuptial flight. Twenty females or fewer are found in a single colony, while males are much more common. The nuptial flight begins at different times for each species; they have been recorded in mid-summer to autumn (January to early April), but there is one case of a nuptial flight occurring from May to July. Ideal conditions for nuptial flight are hot stormy days with windspeeds of 30 km/h (18 mi/h) and temperatures reaching 30 °C (86 °F), and elevations of 91 metres (300 ft). Polygynous and polyandrous societies can occur in a single nest, but particular species are either primarily polygynous or primarily polyandrous. For example, nearly 80% of tested
M. pilosula colonies are polygynous Nuptial flight takes place during the morning and can last until late afternoon. When the alates leave the nest, most species launch themselves into the air from trees and shrubs, although others launch themselves off the ground. Queens discharge a glandular secretion from the tergal gland, which males are strongly attracted to. As many as 1,000 alates will gather to mate. A queen was once found to have five or six males attempting to copulate with her. but one study showed that it is possible for multiple queens in the same colony to be genetically related to each other. Depending on the species, the number of individuals present in a colony can range from 50 to over 2,200 individuals. A colony can last for a number of years. Foraging behaviour among smaller workers which never usually leave the nest can be a sign of a colony's impending demise. However, this is not always the case.
Myrmecia is one of several ant genera which possess
gamergate workers, where a female worker is able to reproduce with mature males when the colony is lacking a queen.
Myrmecia workers are highly fertile and can successfully mate with males. A colony of
M. pyriformis without a queen was collected in 1998 and kept in captivity, during which time the gamergates produced viable workers for three years. Ovarian dissections showed that three workers of this colony mated with males and produced female workers. Queens have bigger ovaries than the workers, with 44
ovarioles while workers have 8 to 14. These ants are capable of discriminating the distance and size of objects moving nearly a metre away. Winged alates are only active during the day, as they can see better. Members of a colony have different eye structures due to each individual fulfilling different tasks, Facet lenses also vary in size; for example, the diurnal species
M. croslandi has a smaller lens in comparison to
M. nigriceps and
M. pyriformis which have larger lenses.
Myrmecia ants have three
photoreceptors that can see
UV light, meaning they are capable of seeing colours that humans cannot. Their vision is said to be better than some mammals, such as cats, dogs or wallabies. Despite their excellent vision, worker ants of this genus find it difficult to find their nests at night, due to the difficulty of finding the landmarks they use to navigate. They are thus more likely to return to their nests the following morning, walking slowly with long pauses.
Sting Myrmecia workers and queens possess a sting described as "sharp in pain with no burning." The pain may last for several minutes. In the
Starr sting pain scale, a scale which compares the overall pain of hymenopteran stings on a four-point scale,
Myrmecia stings were ranked from 2–3 in pain, described as "painful" or "sharply and seriously painful". Unlike in
honeybees, the sting lacks barbs, and so the stinger is not left in the area the ant has stung, allowing the ants to sting repeatedly without any harm to themselves. The retractable sting is located in their abdomen, attached to a single venom gland connected by the venom sac, which is where the venom is accumulated.
Exocrine glands are known in some species, which produce the venom compounds later used to inject into their victims. Examined workers of larger species have long and very potent stingers, with some stings measuring . ==Relationship with humans==