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Genus Formica - Wood ants, mound ants, & field ants

Unknown ant - Formica - female Queen Ant - Formica incerta Ant? - Formica Ant - Formica obscuriventris ant nest visitor - Formica exsectoides - female Unknown Ant - Formica pallidefulva Formica (black ant) - Formica ants - Formica podzolica
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon (Aculeata - Ants, Bees and Stinging Wasps)
Superfamily Formicoidea (Ants)
Family Formicidae (Ants)
Subfamily Formicinae
Tribe Formicini
Genus Formica (Wood ants, mound ants, & field ants)
Pronunciation
Anglicized - for-MY-kuh (preferred), FOR-micka (also heard)
Latin - for-MEE-kah
Synonyms and other taxonomic changes
Formica Linnaeus, 1758
Explanation of Names
Formica is the Latin word for "ant", still found in various derivations in the modern languages derived from Latin, e.g., French fourmi, Spanish hormiga, Portuguese formiga, etc. It was first used by Linnaeus for all ants (i.e. equivalent to Formicidae). That Linnean genus is now divided up onto about 15 subfamilies and almost 300 genera).
Numbers
97 North American species in Formica (1) (2)
Size
Workers -- 4-8mm, stretched out, from border of clypeus to tip of abdomen. Some are weakly polymorphic.
Alates -- 5-13mm (males and female about the same length in each species)
Identification
4-8 mm workers have conspicuous ocelli, double row of bristles on flexor (ventral) surface of middle and hind tibiae, mesosoma with "bumpy" (stair-stepped) profile, dorsal surface of propodeal profile as long or longer than the posterior, declivitous face.
Antennomere and palp segment counts are typical for Aculeata, antennae 12-segmented (13 in males), palp formula 6,4.
Range
Northern Hemisphere, Warm Temperate to Subarctic Zones.
(Extends into Tropics at high elevations south to Honduras.)
Habitat
Known as wood (or forest) ants, field ants or mound ants, depending on habitat preference and nesting habits of the various species. Most prefer non-flooded, open woodlands, openings in temperate forest, or grasslands. A few (mostly northern) species are more or less specialists in openings in boreal forests, fens or bogs, riparian areas, and a small number of species can (but do not always) live in the full shade of closed canopy deciduous or mixed forests. Nests are built in soil or less often in rotten wood on the ground. The nest may be elevated above the surface as a mound constructed of earth and/or plant fragments.
Season
Active from the first warm days of spring till frost, but often with an unexplained lull in activity in August. Mating flights late June through early August.
Food
Predatory with a sweet tooth. Attack and kill or scavenge all manner of arthropods and less often earthworms, and avidly seek honeydew and extrafloral nectar, often foraging high in trees to gather these sweets.
Life Cycle
Mating flights peak late June through early July in the South, a little later at high elevations and latitudes. Many or possibly all species in the rufa, microgyna, exsecta & sanguinea groups have dependent colony foundation, effected by mated queens entering a colony of her own species and joining the queen numbers there, or of a fusca, neogagates, pallidefulva group species and usurping the resident queen(s). Colonies are nearly always founded by individual queens in these host groups, but some may form small groups, or re-enter a (probably related) colony of their own species
Remarks
The fusca, pallidefulva & sanguinea groups have been revised, but the taxonomy is still difficult, as differences among the species are subtle, and often the diagnostic characters are not depicted in images posted at BG. The rufa/microgyna & neogagates groups are much in need of revision, so Creighton (1950) must serve for their identification.
See Also
Lasius are perhaps most similar and found in the same habitats, differing in their inconspicous or missing ocelli, lack of a pair of longitudinal rows of bristles on the flexor (ventral) surfaces of the middle and hind tibiae, and by the dorsal surface of the propodeum being shorter than the posterior declivitous face. Lasius also differ in their smaller size (2.5-4), small eyes, and reduced palp segmentation of many species.
Myrmecocystus workers are of similar size and coloring to many Formica, but may be recognized by their very elongate maxillary palp, and desert habitat. Camponotus minor workers are in the size range, but have a flat to gently curved mesosomal profile, i.e., pro-metanotal profile continuous with propodeal profile rather than "stair-stepped".