Subfamily Formicinae

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

2. 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.

3. Brachymyrmex Genus Brachymyrmex Descriptive Characteristics: Habitat and ecology: - Tiny, soft bodied ants - Moist habitats, in deserts also when wet - Antennae with 9 segments (if < 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.

4. Convex Mesosoma 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).

5. Propodeum lower than Mesonotum Depression Big Eyes Maxillary palps Head of a worker of Formica obscuripes. Ocelli often very distinct 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 • Won’t 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

6. Maxillary and Labial palps 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.

7. Last 3 segments of the maxillary palp 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

8. 12 segments Dark coarse hairs 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

9. Head of a worker of Polyergus breviceps 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.

10. Alitrunk hour-glass shape Hour glass-like shape 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 shapeof the mesosoma (seen from above) separates this genus from all other formicines.

11. 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.

12. 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.

13. 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.

14. Genus Plagiolepis • Descriptive Characteristics: Habitat: • Behavior • Note:.