Commonly, red head and mesosoma, and black gaster, als

1
Subfamily Formicinae
Compiled by Hilda Taylor and William Mackay
Polyergus rufescens invade the nest of Formica
fusca
Descriptive Characteristics - Apex of gaster
with semicircular to circular acidopore
(easiest to see in smaller ants) - Postpetiole
fused to gaster - Stinger absent Habitat -
Worldwide, deserts to alpine areas Behavior
- Most genera are non aggressive Note Easily
confused with Dolichoderinae - Stinger is absent
on both Dolichoderinae has a transverse
cloacal orifice and Formicinae has the
circular acidopore - Dolichoderinae has a strong
scent, formicines may smell like formic acid.
Acidopore
Inside the nest of Myrmecocystus mimicus, Honey
Pot ants
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Genus Acanthomyops
Descriptive Characteristics Habitat and
ecology - Propodeum, rectangular shape (seen
from side) - Forests, cool and moist habitats -
Metanotal suture, well below level of mesosoma -
Found under rocks, soil, surface, up -
Maxillary palp with 3 segments on trees if
tending aphids palps almost not visible -
Tiny mounds - Pretty light yellow - Not very
common - Queen very different from worker, they
may have - Fast, but slower in cool habitats,
thick flat legs try to find males and
especially females Behavior Not
aggressive, escape with brood -Parasites on
Lasius Note Very similar to Lasius. If
maxillary palps cannot be seen then it is
probably an Acanthomyops.
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Genus Brachymyrmex
Descriptive Characteristics Habitat and
ecology - Tiny, soft bodied ants - Moist
habitats, in deserts also when wet - Antennae
with 9 segments (if lt 12 then nearly - Only few
species found in USA always
Brachymyrmex) - Many species in Mexico and
tropics - Brownish-grayish in color or
yellowish Behavior Not aggressive Notes
1) Brachmyrmex, spp. very similar in field to
Tapinoma, spp. Gaster overlaps petiole on both.
Lacks smell of Tapinoma. 2) Some species
(Neotropical) have coarse hairs on mesosoma
(similar to Paratrechina), but have 9-segmented
antenna, instead of 12-segmented antenna.
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Genus Camponotus
C. herculeanus
C. sansabeanus
Descriptive Characteristics Habitat and
ecology - Polymorphic (usually), often very
large - Tropics to deserts to alpine habitats -
12 segmented antennae - Nest in the ground,
rocks, logs, stumps, - Maxillary palps with 6
segments twigs, and termite mounds
(tropics) - Mesosoma convex (nearly always) -
Look on Mesquite bushes, oaks and any - All have
a large distance between the insertions of other
desert shrubs with a 5 - 10 cm the antennae and
the posterior edge of the clypeus diam. for
subgenus Colobopsis other fascinating
species. Behavior Camponotus, spp. usually
rapidly escape, rescue brood, difficult to
capture, some species aggressive and can bite.
Note Convex mesosoma separates
it from other genera, except Liometopum
(Dolichoderinae). Those with depressed metanotal
suture easy to confuse with Dolichoderus
(Dolichoderinae, in Neotropics).
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Genus Formica
Formica ciliata worker.
Formica densiventris worker.
Formica ravida workers.
Ocelli

• Descriptive Characteristics Habitat and
  ecology
• - Polymorphic, different sizes of workers -
  Abundant at higher elevations
• - Frontal carinae prominent - Pine forests in
  USA and Mexico
• - Ocelli often very distinct (top of head) -
  Cool and moist habitats (deserts)
• - Long maxillary palps - Nests can be large or
  small
• - Large eyes - Predaceous
• - Pronotum often lower than mesonotum
• - Depression between pronotum and mesonotum
• - Commonly, red head and mesosoma, and black
  gaster,
• also solid colors (yellow, brown)
• Behavior
• Fast, observant, not afraid
• Wont attack if it is a small nest, most likely
  will attack if it is a large nest
• Squirt formic acid. Curves gaster under body,
  aims and squirts formic acid at you

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Genus Lasius
Propodeum
6 segments

• Descriptive Characteristics Habitat and
  ecology
• Maxillary palps with 6 segments - Pine forests,
  high elevation grasslands
• Maxillary palps very obvious - Also found in
  deserts
• Propodeum rectangular, usually pointed - Common
  in Mexico and USA Behavior Slow, not
  aggressiveNote Very similar to Acanthomyops
  ants, differ in number of segments of maxillary
  palps.Species in both genera often yellow. If
  you can see the maxillary palps, it is probably
  Lasius.

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Genus Myrmecocystus (Honey Pot Ants)
Myrmecocystus mexicanus

• Descriptive Characteristics Habitat and
  ecology
• Maxillary palp - Common in deserts in
• Segment 4 very long, count from end SW
  ecosystems,
• - Psammophore sometimes present - Also found
  in Piñon-Juniper habitats
• - Nest mound with pebbles with a
• hole of 3 cm diam.
• - Feed on liquid food (honey, nectar)
• and honeydew from homopterous
• insects
• - Also feed on dead insects
• Behavior
• - Fast, difficult to catch
• - Hang from roof of nest Notes Maxillary
  palps separate it from the similar Formica

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Genus Paratrechina

• Descriptive Characteristics Habitat
• 12 segmented antennae - Temperate North
  America and south,
• Dark coarse hairs on pronotum and mesonotum
  common throughout southern USA
• viewed from directly above, mesosoma lacking
  and Mexico.
• hourglass-like shape - Found under rocks
• - Eyes located towards the mid-front of the head
  - Found in baits
• Behavior Not aggressive
• Note Resembles Brachymyrmex, spp. but they have
  different number of antennal segments
• Brachymyrmex has 9 antennal segments
  and Paratrechina, spp. has 12 antennal segments

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Genus Polyergus
Petiole Prominent
Long mandibles

• Descriptive Characteristics Habitat
• Mandibles long, sickle shaped - Temperate and
  mountainous North
• Red-brown in color America south into
  Mexican high-
• Petiole with prominent rounded node
  lands - Cannot feed themselves, need
  Formica slavesBehavior
• Social parasites on Formica, spp.
• Invade Formica ants nests, convince workers that
  she is queen and soon they take over
• Trails like army ants
• Note Resemble Formica ants, but mandibles are
  different.

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Genus Prenolepis

• Descriptive Characteristics Habitat and
  ecology
• Mesonotum, if viewed from, above very slender, -
  Temperate and mountainous USA and
• the mesosoma has hourglass-like shape in
  Mexican highlands
• - Golden or brownish mesic type areas
• Piñon-Juniper forests
• semi-arid habitats
• Behavior Non aggressive
• Note The shape of the mesosoma (seen from above)
  separates this genus from all other formicines.

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Rare genera
Genus Acropyga
Acropyga

• Descriptive Characteristics Habitat and
  ecology
• - Small, clear yellow ants, tiny ants. -
  Subterranean
• - Elongate scape. - Tend coccids on roots
• - Maxillary palps with 2 segments. - Rarely
  collected, but probably common
• - Labial palps with 3 segments.Behavior
• - Slow ants which rescue brood and
• coccids when the nest is disturbed.
• Note.The tiny eyes separate this genus from most
  others in the subfamily.

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Genus Anoplolepis

• Descriptive Characteristics Habitat and
  ecology
• - Scape very long - Usually a pest species in
  urban habitats
• - Medium sized ants
• - Maxillary palps long, with 4 segments
• - Labial palps with 4 segments
• Behavior
• Move very rapidly
• Alert ants
• Note.These long-legged, long scaped ants are not
  likely to be confused with any other formicine
  ant genus.

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Genus Myrmelachista

• Descriptive Characteristics Habitat and
  ecology
• - Antenna with 9 or 10 segments - Nests in
  twigs.
• - Club with 3 segments
• Behavior
• Hide and rescue brood.
• Note.This genus is very similar to Brachymyrmex,
  but has an antennal club.

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Genus Plagiolepis

• Descriptive Characteristics Habitat
• Behavior
• Note.