You must first be sure that the specimen you are keying is in fact a Formicid. Many insects mimic ant behavior and morphology. Some beetles and spiders look and act fairly ant-like but with close examination it should be obvious that these are not ants.

It can be much more difficult to distinguish ants from their close relatives, other members of the Order Hymenoptera (ants, wasps, and bees). Note that ants are in the family Formicidae, bees in the superfamily Apoidea (or Sphecoidea, depending on whether the ancestral family Spechidae is included), which includes families such as the Apidae, Halictidae, etc., and wasps are every other Hymenopteran family (such as Vespidae, Ichneumonidae, and many others).

Several wasp families with wingless females, especially the velvet ants (Mutillidae), the Bethylidae, and the Tiphiidae look very much like ants. Some wingless ichneumonids (Ichneumonidae) even look ant-like. Confounding matters even more, most reproductive ants are winged, at least until they mate, and may look rather wasp-like.

Which of these Hymenopterans are ants?

These specimens are (from left to right, top to bottom): an interesting ant-like Hymenopteran which may be a Tiphiid, a male velvet ant, an ant (a winged male Ponera pennsylvanica), a female velvet ant, an ant (a winged male Formica obscuripes), and an ichneumonid.

Ants are distinguished from these ant-like groups by a few morphological characters: ants have 6-13 antennal segments, the first (=scape) of which is lengthened to cause a characteristic bent antenna (note though that some male ants, such as the Ponera pictured above does not have lengthened scapes and bent antenna), and most importantly, a humplike node at the petiole, the segment at the junction between the thorax and abdomen (Bolton 1994 and Gauld and Bolton 1988).

These characters are often not obvious and it may be difficult at first to be sure the Hymenopteran is in fact a member of the family Formicidae. After a while though, it is usally possible to recognize ants by their gestalt.

Please send any questions or comments regarding these pages to Tim Linksvayer or Andy McCall