New England Ant Identification

Covering the six New England states, Maine, Vermont, New Hampshire, Massachusetts, Connecticut and Rhode Island.

The keys below are based on the 2012 book A Field Guide to the Ants of New England.

Aphaenogaster
6 species

1


 * The first gastral tergite has long, distinct lines or grooves (striae) that radiate in a sunburst pattern from the postpetiole; head and mesosoma coaresly scultpured with dense, anastomosing ridges (rugae); the propodeal spines are very long – at least as long as the distance between their tips . . . . . Aphaenogaster mariae


 * First gastral tergite lacks striae; sculpturing on head and mesosoma fine; the propodeal spines normally are not longer than the distance between their tips, but if they are, the mesosoma and gaster are hairless . . . . . 2

2 (1)
 * The cheeks, as well as the dorsum of the mesosoma and gaster are hairless; the propodeal spines are very long – at least as long as the distance between their tips . . . . . Aphaenogaster tennesseensis


 * Cheeks, mesosoma, and gaster with many erect hairs; propodeal spines normally not longer than the distance between their tips . . . . . 3

3 (2)
 * Base of antennal scape with a wide, thick lobe extending about 1/4 of the length of the scape . . . . . Aphaenogaster treatae


 * Base of antennal scape without a lobe . . . . . 4

4 (3)
 * The last four segments of the antennae are the same color as the remaining segments; the propodeal spines are short – not more than ½ the length of the propodeal declivity (rear-sloping face) – and pointed upward; the top (peak) of the mesonotum not higher than the top of the pronotum . . . . . Aphaenogaster rudis - a species complex
 * The last four segments of the antenna are ligher in color or paler than the remaining segments; propodeal spines at least 2/3 the length of the propodeal declivity and pointed either upwards or towards the rear; top (peak) of the mesonotum as high or higher than the top of the pronotum . . . . . 5

5 (4)
 * Propodeal spines long – at least as long as the propodeal declivity – and pointing upwards; color reddish-brown . . . . . Aphaenogaster fulva


 * Propodeal spines shorter – approximately 2/3 the length of the propodeal declivity – and pointing towards the rear; color dark brown or blackish-brown . . . . . Aphaenogaster picea - a species complex

Brachymyrmex

 * Brachymyrmex depilis

Brachyponera

 * Brachyponera chinensis

Camponotus

 * Camponotus americanus
 * Camponotus caryae
 * Camponotus castaneus
 * Camponotus chromaiodes
 * Camponotus herculeanus
 * Camponotus nearcticus
 * Camponotus novaeboracensis
 * Camponotus pennsylvanicus

Crematogaster
2 species


 * No erect hairs on mesosoma except for 1-2 pairs of erect hairs on the corners of the pronotum . . . . . Crematogaster cerasi


 * Many (8-20) short hairs on the pronotum and scattered elsewhere on the mesosoma . . . . . Crematogaster lineolata

Dolichoderus
4 species

There are only 4 species of Dolichoderus in all of North America. All of these species have a range that includes New England. Key to North American Dolichoderus Species

Forelius

 * Forelius pruinosus

Formica

 * Formica adamsi
 * Formica argentea
 * Formica aserva
 * Formica cf. fossaceps'' - an undescribed species
 * Formica creightoni
 * Formica dakotensis - occurs in bordering areas and is likely to be found in New England
 * Formica difficilis
 * Formica dirksi - only known from type specimens
 * Formica dolosa
 * Formica exsectoides
 * Formica glacialis
 * Formica hewitti
 * Formica impexa
 * Formica incerta
 * Formica integra
 * Formica knighti
 * Formica lasioides
 * Formica morsei - only known from type specimens
 * Formica neogagates
 * Formica neorufibarbis
 * Formica nepticula
 * Formica obscuriventris
 * Formica pallidefulva
 * Formica pergandei
 * Formica podzolica
 * Formica querquetulana
 * Formica reflexa
 * Formica rubicunda
 * Formica subaenescens
 * Formica subintegra
 * Formica subsericea
 * Formica ulkei

Formicoxenus

 * Formicoxenus provancheri

Harpagoxenus

 * Harpagoxenus canadensis

Hypoponera

 * Hypoponera punctatissima - non-native species

Lasius

 * Lasius americanus
 * Lasius cf. niger - this may be an undescribed species
 * Lasius cf. umbratus'' - an undescribed species
 * Lasius claviger
 * Lasius flavus
 * Lasius interjectus
 * Lasius latipes
 * Lasius minutus
 * Lasius murphyi - occurs in bordering areas and is likely to be found in New England
 * Lasius nearcticus
 * Lasius neoniger
 * Lasius pallitarsis
 * Lasius plumopilosus - occurs in bordering areas and is likely to be found in New England
 * Lasius speculiventris
 * Lasius subglaber
 * Lasius subumbratus
 * Lasius umbratus

Leptothorax

 * Leptothorax retractus
 * Leptothorax sp. AF-can - an undescribed species
 * Leptothorax sp. AF-erg - an undescribed species
 * Leptothorax sphagnicola - occurs in bordering areas and is likely to be found in New England
 * Leptothorax wilsoni

Monomorium
4 species

1


 * Ant concolorous, dark green to black . . . . . 2


 * Ant bi-colored, or if concolorous, then yellow-to-light brown with a black-tipped gaster . . . . . 3

2
 * Length of the dorsal surface of the propodeum is shorter than the length of the sloping, posterior surface of the propodeum (the declivity); body black; widespread throughout New England . . . . . Monomorium emarginatum


 * Length of the dorsal surface of the propodeum is longer than the length of the declivity; body dark green to black; nests only in pure sandy soils . . . . . Monomorium viridum

3


 * Ant uniformly yellow-red or light brown, except for the gaster, which is at least dark brown or black at the tip, but may be entierely dark brown or black . . . . . Monomorium pharaonis


 * A bi-colored ant with a dark head and gaster and a light brown mesosoma . . . . . Monomorium floricola

Myrmecina

 * Myrmecina new species - an inquiline social parasite of Myrmecina americana
 * Myrmecina americana

Myrmica

 * Myrmica alaskensis
 * Myrmica americana
 * Myrmica brevispinosa
 * Myrmica detritinodis
 * Myrmica fracticornis
 * Myrmica incompleta
 * Myrmica lampra - occurs in bordering areas and is likely to be found in New England
 * Myrmica latifrons
 * Myrmica lobifrons
 * Myrmica nearctica
 * Myrmica pinetorum
 * Myrmica punctiventris
 * Myrmica quebecensis - occurs in bordering areas and is likely to be found in New England
 * Myrmica rubra - non-native species
 * Myrmica scabrinodis - non-native species
 * Myrmica semiparasitica
 * Myrmica sp. AF-eva - an undescribed species
 * Myrmica sp. AF-ine - an undescribed species
 * Myrmica sp. AF-scu - an undescribed species
 * Myrmica sp. AF-smi - an undescribed species
 * Myrmica sp. AF-sub - an undescribed species

Nylanderia
3 species

1
 * Antennal scapes without erect hairs; workers lack ocelli; a native, widespread species . . . . . Nylanderia parvula


 * Antennal scapes with at least one erect hair, workers with many more hairs; workers, if present, have small ocelli	2

2
 * Antennal scapes of workers and queens with many erect hairs; workers with small ocelli; an introduced species currently recorded in New England only from inside heated buildings and greenhouses . . . . . Nylanderia flavipes


 * Colonies consisting of queens and males relying on host workers of N. parvula; queens have at least one erect hair on at least one of the antennal scapes, but host workers lack erect hairs on their antennal scapes; queens < 2 mm long . . . . . Nylanderia deceptrix

Paratrechina

 * Paratrechina longicornis - non-native species

Pheidole
2 species


 * In dorsal view, the post-petiole of the major workers is more-or-less diamond-shaped with sharp corners; ant brown; our only native New England species . . . . . Pheidole pilifera


 * In dorsal view, post-petiole of the majors is more-or-less round or oval-shaped, lacking sharp corners; ant yellow; a tropical species encountered in New England only indoors	. . . . . Pheidole flavens

Polyergus
3 species

1
 * The workers have 20 or more, coarse, dark, erect hairs on the rear margin of their heads; the host is Formica dolosa; this largest of our Polyergus species has workers generally > 6.5 mm long . . . . . Polyergus cf. longicornis - an undescribed species


 * Workers with < 10 erect hairs on the rear margin of the head; enslaves other Formica species, but never F. dolosa. Workers generally < 6 mm long . . . . . 2

2
 * Workers with at least 5, and usually 10 erect hairs on the rear margin of the head; enslaves F. incerta; body very shiny, head usually shiny . . . . . Polyergus lucidus


 * Workers usually with no erect hairs, but never more than 5 erect hairs, on the rear margin of the head; enslaves Formica pallidefulva; body and head with a matte (not shiny) appearance; occurs in bordering areas and is likely to be found in New England . . . . . Polyergus montivagus

Ponera

 * Ponera pennsylvanica

Prenolepis

 * Prenolepis imparis

Proceratium
3 species

1


 * Second gastral segment enlarged; subsequent segments located below and near the front of the second segment; anterior border of the clypeus slightly convex with a projecting median lobe; petiole low and rounded when viewed from above . . . . . Proceratium pergandei


 * Third and later gastral segments located below but near the back of the second segment; anterior border of clypeus without a median lobe; petiole relatively high and rectangular when viewed from above . . . . . 2

2
 * Petiole thick in profile (the crest is almost as thick as the base); frontal area ¼ as wide as head; frontal carinae diverge towards the top of the head; erect hairs on gaster short and sparse . . . . . Proceratium crassicorne


 * Petiole slender in profile (crest distinctly thinner than base); frontal area >¼ as wide as head; frontal carinae strongly divergent towards the bottom of the head. Erect hairs on gaster long and dense. . . . . . Proceratium silaceum

Solenopsis
2 species


 * In dorsal view, the post-petiole is noticeably wider than the petiole; in profile view, the summit of the petiole is relatively narrow; the ant is yellow-brown and nests in a wide variety of soils, but never in pure sand . . . . . Solenopsis molesta
 * In dorsal view, the post-petiole is approximately as wide as the petiole; in profile view, the summit of the petiole is relatively broad; a lemon-yellow ant that nests only in pure sand . . . . . Solenopsis cf. texana

Stenamma
4 species

1
 * Compound eye with 5 – 12 facets (ommatidia) in its widest diameter, and > 20 facets total; relatively large for a Stenamma (total length 2.75 – 4.0mm) . . . . . Stenamma brevicorne


 * Compound eye with 3 – 6 facets in its widest diameter and < 15 facets total; a smaller species (total length 2 – 3.5mm) . . . . . 2

2
 * Compound eyes very small, consisting of 3 – 6 facets; mesosoma sculptured with pronounced punctures, giving the ant a matte appearance . . . . . Stenamma schmittii


 * Compound eyes larger, consisting of 8 – 15 facets . . . . . 3

3


 * Compound eye with 4 – 5 small facets across its widest diameter; total length 2.7 – 3.5mm; conspicuous sculpturing on the pronotum, but the promesonotum and the post-petiole are usually smooth and shiny; common north of Massachusetts . . . . . Stenamma diecki


 * Compound eye with 5 – 6 coarse facets across its widest diameter; total length 2.3 – 2.7mm; sculpturing on the mesosoma is faint, and extends to the promesonotum and post-petiole (i.e., not smooth and shiny); more common in Massachusetts and southern New England . . . . . Stenamma impar

Stigmatomma

 * Stigmatomma pallipes

Strumigenys
3 species

1


 * In full face view, mandibles elongate, narrow, and with teeth only on the anterior third to half of the mandibles; the first (basal) and third mandibular teeth are sharp, but the second mandibular tooth is broad and blunt . . . . . Strumigenys pergandei


 * In full face view, mandibles triangular-to-elongate, with teeth along the entire surface except for a small gap between the clypeus and the basal tooth . . . . . 2

2


 * The hairs on the clypeal margins, both lateral and anterior, curve towards the mandibles; paired erect hairs on dorsum, mesonotum, and first gastral segment are long, straight, and sharp; antennal hairs curved; antennal hairs closest to the base of the scape have broad, rounded (spatulate) ends, those further up the scape are not blunt-tipped . . . . . Strumigenys metazytes


 * Hairs on the lateral clypeal margins curve towards the mandibles, but those on the anterior margin curve away from the mandibles; paired erect hairs on dorsum, mesonotum, and first gastral segment are short and whip-like (flagellate); antennal hairs curved and all are spatulate . . . . . Strumigenys pulchella

Tapinoma
3 species

1


 * Workers tiny, < 1.5 mm long; head and mesosoma brown, gaster and legs milky white; a tropical species that is a rare inhabitant of greenhouses and other heated structures in New England . . . . . Tapinoma melanocephalum


 * Workers larger, 2.5 – 3.5 mm long; ants uniformly brown . . . . . 2

2 


 * Queens generally large, at least 5.5 mm; queens and males produced and fly in mid-summer (late July to early August) . . . . . Tapinoma sessile


 * Queens much smaller, 2.0 – 2.5 mm long; queens and males produced and fly in late summer (mid-August to late September); a rare inquiline social parasite of T. sessile. Note: workers are not produed by this species – if workers are observed in the colony, they are the workers of the host, T. sessile . . . . . *Tapinoma new species

Temnothorax
6 species

One species, Temnothorax americanus was not included in this key as in 2012 it was considered to be Protomognathus americanus. This species is a social parasite of a number of Temnothorax species that occur in New England.

1
 * The post-petiole is massive – its width is 1.5X the width of the petiole; antennae with 12 segments; roughly sculptured with rugae on head, mesosoma, petiole, and post-petiole; gaster smooth and glossy; color dark brown/black . . . . . Temnothorax texanus


 * Post-petiole < 1.25X width of the petiole; antennae with 11 segments; color black or orange-yellow . . . . . 2

2
 * Head covered with fine lines (striae); propodeal spines short, length < ½ the distance between their bases; color normally dark brown . . . . . Temnothorax schaumii


 * Head smooth or with net-like (reticulate) sculpturing, but not finely striated; propodeal spines longer than ½ the distance between their bases; color yellowish-orange to dark brown or black . . . . . 3

3
 * A dark brown to black ant; dorsum of head smooth, shining; propodeal spines very long, pointing nearly straight back . . . . . Temnothorax longispinosus


 * A yellowish-brown ant; top of head sculptured . . . . . 4

4
 * Propodeal spines well-separated at base; each spine shorter than the distance separating their bases; gaster uniform in color; post-petiole notably broader than long . . . . . Temnothorax ambiguus


 * Propodeal spines close together at base; each spine much longer than the distance separating their bases; gaster with a dark splotch or stripe; post-petiole nearly square (subquadrate), i.e., not significantly broader than long . . . . . Temnothorax curvispinosus

Tetramorium

 * Tetramorium atratulum - non-native species
 * Tetramorium immigrans - non-native species

Tetramorium immigrans, the sidewalk ant, is a common ant in urban and suburban areas. Tetramorium atratulum is a workerless inquiline that parasites T. immigrans. The parasite has only been collected a handful of times in North America.