Among acrobat ants, workers are usually 2.6 to 4.0 mm long and queens are 7.0 to 8.0 mm long. These ants range from reddish-brown to dark brown to black in color. Ants of their genus (Crematogaster) have a unique heart shaped final body segment, which is flat on their back but rounded toward their belly. Their antennae have 11 segments and 3 segments on their antennal club. The narrow spot dividing their body segments is flat. It is fairly easy to identify members of this genus, but individual species are more difficult. Acrobat ants can be identified by the one or two long hairs that stand up on each corner of their first segment. Males and breeding females have wings, while workers do not. Queens lose their wings after mating. Larvae are 1.0 to 1.1 mm long when they first hatch and can grow to 1.9 mm long. Larvae are curved and segmented and become smooth when they are ready to molt. (Ellison, et al., 2012; Mackay and Mackay, 2003; Rice, 2013; Smith, 1965; Thompson, 1990; Wheeler and Wheeler, 1973)
Acrobat ants (Crematogaster cerasi) are found in southern Canada, throughout much of the United States, and into northern Mexico. In the United States, they are found in the west to the Rocky Mountains and New Mexico, east to the eastern coastal states, and as far south as Florida. They are especially common in the Midwest and in the northeastern states. (Johnson, 1988; Smith, 1965)
Acrobat ants mostly build their nests in trees such as under bark, in hollow stems, or in other cavities, but they can also live in logs and stumps or under leaf litter and stones. These ants also nest inside houses and other buildings, usually in tight spaces such as between shingles and in or around doors and windows. They are most common in forests, but can also be found in grasslands, pastures, bogs, and marshes. They are even occasionally found in mountain regions, as high as 2,350 m. In the southern part of their range, they tend to live in drier habitats, while in the north they are more frequent in wetter woodlands and fields. (Ellis, et al., 2000; Jander, 1990; Johnson, 1988; Kannowski, 1959; Mackay and Mackay, 2003; Rice, 2013; Smith, 1965; Thompson, 1990)
Ants are holometabolous, which means they have an egg, larva, pupa, and adult stage. Eggs hatch into larvae, which need a great deal of care from the adults to survive. They then develop into pupae, which eventually develop into adults. For a short period time after the pupal stage, the adult ants are in a callow stage, where the ant is white in color, weak, and less active. Most offspring develop into female workers. Males and winged females are present in the nest in late summer. (Kannowski, 1959)
Acrobat ants mate in late summer, after males and winged females have hatched and developed. Breeding adults can be seen starting in July. The ants breed and swarm in nuptial flights, which happen in late July to early September. Females only mate once in their lives and males die shortly after mating. (Kannowski, 1959; Marshall, 2006)
After mating, the queens look for good locations to begin a new colony. Queens often take shelter in abandoned beetle or termite galleries in tree branches while they remove their wings. Some may overwinter before producing a brood, while others begin egg production soon after. Queens have a very high mortality rate at this point and only a few mated females successfully create a colony. The first batch of eggs develops into workers that tend the queen and future broods. Later when the colony is established, breeding females and males are produced. Queens store sperm and lay eggs throughout their lives. Although the workers are female, they do not mate. Colonies from this genus can last 10 to 15 years. This species may have several queens per nest, as nests often include several females with removed wings. (Kannowski, 1959; Mackay and Mackay, 2003; Rice, 2013)
Among acrobat ants, female workers invest significant care in the queen's brood. Since the larvae and pupae are helpless, the workers must tend them and bring them food. Workers feed the brood by trophallaxis, which is mouth to mouth regurgitation of food. Workers also protect the brood from threats. Beetles often live in acrobat ant nests and are removed by workers if they go near the brood. (Leschen, 1991; Marshall, 2006)
Males live only a few weeks to a month, and die shortly after mating. While the lifespan of acrobat ants is not known, it is likely similar to many other ant species, with workers living several months. Colonies can continue for more than 10 years, so queens likely live several years. (Marshall, 2006; Rice, 2013)
Acrobat ants look for food both during the day and night. Workers mark trails with pheromones for their nest mates to follow. They move in lines, with one ant following another. This species is mainly arboreal, building their nests and looking for food in the trees, however, they can also nest in leaf litter, under stones, or in buildings. Their colonies can be very large, with 10 thousand or more ants. Species in their genus perform a distinct behavior when they are disturbed, which gives them the common name 'acrobat ants'. The connection between their middle and final segment is very flexible, which allows them to hold their final segment up over their head and body, and wave it in the air when they are alarmed. Acrobat ants divide labor between the workers and breeding ants. Winged males and females mate, and then females start new colonies and produce young. Workers take care of the young, look for food, and protect the nest. (Ellis, et al., 2000; Ellison, et al., 2012; Marshall, 2006; Rice, 2013; Thompson, 1990)
There is currently no information available about the home range size of these ants.
Ants use their antennae as their main sensory organ. Their antennae are used to sense chemicals and pheromones, to identify nest mates and breeding mates, and also to feel the space around them. Ants groom their antennae to prevent a buildup of chemicals and particles. Pheromones are important for communication between ants. Acrobat ants let off alarm pheromones to warn their nest mates of a threat. Ants of this genus also use trail pheromones to mark paths to food sources and other locations. These ants are unique, as the gland for trail chemicals is in their hind legs, not in their final segment. Most ants use the tip of their last segment to lay trail pheromones, but the unique shape of their final segment prevents it from reaching the ground. (Boroczky, et al., 2013; Crewe, et al., 1972; Morgan, et al., 2004)
Acrobat ants are omnivorous. They eat nectar and a sweet substance known as 'honeydew' produced by other insects such as aphids. They also eat parts of seeds. Acrobat ants can also be predators. They prey on live insects and also scavenge dead insects. Ants that find their way inside homes and buildings eat almost any human foods they can find. (Beattie and Culver, 1981; Rice, 2013; Smith, 1965; Stephenson, 1981; Thompson, 1990)
Acrobat ants are preyed on by spiders, beetles, and other insects, as well as birds, small mammals such as mice, and occasionally black bears. (Noyce, et al., 1997; Rice, 2013)
In some forest areas, acrobat ants are one of the main ant species. They prey on other insects and are preyed on by other animals including spiders, birds, bears, and other insects. These ants transport seeds and only eat part, leaving the rest to germinate. They also form relationships with honeydew producing insects such as aphids and scale insects. In turn for eating the honeydew these insects produce, the ants provide care and protection. Some of the aphid species they tend include yellow sugarcane aphids, apple aphids, spirea aphids, and snowball aphids, as well as scale insects such as calico scales and magnolia scales. Acrobat ants often have other insects, such as the beetle Fustiger knausii living in their nests, although the ants are not usually affected. The ants do not seem bothered by the beetles, though the workers will remove beetles if they are near the brood. Workers will groom the beetles, and vice versa. The beetles will also ride on the ants; the ants do not respond and appear unaffected. They may even transfer food mouth to mouth. Crickets of genus Myrmecophilus also often live in their nests, with no effect on the ants. There are also several species of mites that attach themselves to workers and ride to new locations. The mites are not parasitic and the ants are not bothered. Acrobat ants do have one known parasitoid species, phorid flies, the larvae of which develop inside the ant's head and eventually kill it. (Beattie and Culver, 1981; Bradshaw, et al., 2010; Campbell, et al., 2013; Ellis, et al., 2000; Ellison, et al., 2012; Leonard, 1971; Leschen, 1991; Rice, 2013; Smith, 1965; Steyskal, 1944; Vanek and Potter, 2010)
Acrobat ants can be household pests and are especially common in the northeastern United States. These ants can live in tight spaces inside homes and just outside buildings, traveling inside to feed. They do not cause very much damage, but they are still a nuisance. They can be strangely difficult to squish, acrobat ants that are stepped on or hit seem stunned, before straightening out and going back to work. They can also have a painful bite. They often nest in wood that has been damaged by other species, and they usually enlarge the cavities, causing more damage. Since they tend honeydew producing insects including many crop pests, acrobat ants may indirectly cause crop damage. Since they protect aphids and other pests from predators, they allow the pests to continue feeding. They may also help pass on the poultry tapeworm, Raillietina tetragona. Acrobat ants may carry segments of tapeworm into their nest, which would infect any bird that ate an infected ant. (Bradshaw, et al., 2010; Marshall, 2006; Rice, 2013; Smith, 1965; Thompson, 1990)
There are no known positive effects of acrobat ants on humans.
Acrobat ants are not endangered.
The scientific name of acrobat ants (Crematogaster cerasi) was once Crematogaster lineolata. Sometimes, acrobat ants are called cherry ants, since they were first found tending aphids on a cherry tree. (Ellison, et al., 2012; Gaddy, 1986)
Angela Miner (author), Animal Diversity Web Staff, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
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