wood, mound, and field ants
(Formica spp.)
Overview • Description • Distribution • Taxonomy
Overview |
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Formica is a large genus of ants known as wood, mound, and field ants. It is widespread, occurring throughout the northern hemisphere. There are 290 Formica species worldwide, 97 species in North America north of Mexico, and at least 22 species in Minnesota. The genus Formica have been divided by taxonomists into seven to thirteen species groups based on distinctive features and behavior that can be easily seen in the field. The number of groups and the arrangement of species within those groups is a matter of debate. In 1950 Creighton recognized seven groups. Since then, some of those groups have been divided or renamed. Not all sources have adopted those changes. |
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Most Formica species live in open woodlands, forest openings, shrublands, or grasslands. Many build large mounds covered with thatch. Most are eusocial, the highest level of sociality. They cooperate to care for their offspring and the offspring of other individuals, there are multiple overlapping generations within a colony, and there is a division of labor into specialized castes. A few Formica species are social parasites of one form or another. Some are temporary social parasites, where a queen invades a host colony and kills the queen. She then lays her own eggs and the host workers care for her young. Some species are slave makers, where the queen invades a host colony, kills the host queen, and kills or drives off the host workers. The invading workers do not forage for food. Instead, they raid other colonies of the host species, capture host workers, and return them to the captured nest. The captured workers then do all the foraging for food and cleaning of the nest. Some species are inquiline parasites, where the queen invades a nest but does not kill the host queen. She lays her own eggs, and the host workers tend to both their own and their invader’s young. |
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Description |
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Most Formica ants are large, more than ⅛″ (4 mm) in length. On the worker, the antennae have twelve segments, on the male they have thirteen. They are inserted at or adjacent to the plate on the face (clypeus). The jaws (mandibles) have 7 to 10 prominent teeth. The simple eyes (ocelli) are large and conspicuous. The front part of the body (mesosoma) has three exoskeletal plates on the upper side. The first plate (pronotum) and second plate (mesonotum) cover the thorax. Together they are referred to as the promesonotum. The third plate (propodeum) covers the first segment of the abdomen which is fused to the thorax. When viewed from the side, the propodeum is distinctly lower than the level of the promesonotum. This gives the mesosoma a distinctly “lumpy” appearance. The upper surface at the front of the propodeum is usually longer than the sloping surface at the rear. Sometimes it is evenly rounded, without a clear separation between the upper and rear surfaces. The mesosoma and the rear part of the body (metasoma) are connected by a constricted second segment (petiole). There is a single raised bump (node) on the petiole. |
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Distribution |
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| 8/5/2023 | ||||
Taxonomy |
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Order |
Hymenoptera (ants, bees, wasps, and sawflies) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Suborder |
Apocrita (narrow-waisted wasps, ants, and bees) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Infraorder |
Aculeata (ants, bees, and stinging wasps) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Superfamily |
Formicoidea (ants) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Family |
Formicidae (ants) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subfamily |
Formicinae | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Tribe |
Formicini (wood, mound, field ants, and allies) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subordinate Taxa |
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Synonyms |
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Common Names |
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wood ants field ants mound ants thatching ants |
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Glossary
Clypeus
On insects, a hardened plate on the face above the upper lip (labrum).
Mesonotum
The principal exoskeletal plate on the upper (dorsal) part of the middle segment of the thorax of an insect.
Mesosoma
In Hymenoptera: the front part of the body, consisting of all three segments of the thorax and the first segment of the abdomen, to which the wings are attached.
Metasoma
In Hymenoptera: the armored rear part of the body, consisting of the second segment of the abdomen and all segments posterior to it.
Petiole
On plants: The stalk of a leaf blade or a compound leaf that attaches it to the stem. On ants and wasps: The constricted first one or two segments of the rear part of the body.
Ocellus
Simple eye; an eye with a single lens. Plural: ocelli.
Pronotum
The exoskeletal plate on the upper side of the first segment of the thorax of an insect.
Propodeum
In Hymenoptera: the last segment of the thorax, anatomically the first segment of the abdomen.
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Bill Reynolds |
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The ant is tending to aphids on Fireweed. |
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| Bill Reynolds 7/14/2003 |
Location: Pennington Co. Minnesota The ant is tending to aphids on Fireweed. |
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