Subfamily Formicinae Compiled by Hilda Taylor and William
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 Acidopore 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. Inside the nest of Myrmecocystus mimicus, Honey Pot ants
Genus Acanthomyops Descriptive Characteristics: - Propodeum, rectangular shape (seen from side) - Metanotal suture, well below level of mesosoma - Maxillary palp with 3 segments = palps almost not visible - Pretty light yellow - Queen very different from worker, they may have thick flat legs Behavior: Not aggressive, escape with brood Habitat and ecology: - Forests, cool and moist habitats - Found under rocks, soil, surface, up on trees if tending aphids - Tiny mounds - Not very common - Fast, but slower in cool habitats, try to find males and especially females -Parasites on Lasius Note: Very similar to Lasius. If maxillary palps cannot be seen then it is probably an Acanthomyops.
Genus Brachymyrmex Descriptive Characteristics: - Tiny, soft bodied ants - Antennae with 9 segments (if < 12 then nearly always Brachymyrmex) - Brownish-grayish in color or yellowish Habitat and ecology: - Moist habitats, in deserts also when wet - Only few species found in USA - Many species in Mexico and tropics 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.
Genus Camponotus Convex Mesosoma C. herculeanus C. sansabeanus Descriptive Characteristics: - Polymorphic (usually), often very large - 12 segmented antennae - Maxillary palps with 6 segments - Mesosoma convex (nearly always) - All have a large distance between the insertions of the antennae and the posterior edge of the clypeus Habitat and ecology: - Tropics to deserts to alpine habitats - Nest in the ground, rocks, logs, stumps, twigs, and termite mounds (tropics) - Look on Mesquite bushes, oaks and any other desert shrubs with a 5 - 10 cm 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).
Genus Formica Depression Propodeum lower than Mesonotum Big Eyes Maxillary palps Formica ciliata worker. Formica densiventris worker. Formica ravida workers. Ocelli Head of a worker of Formica obscuripes. Ocelli often very distinct Descriptive Characteristics: - Polymorphic, different sizes of workers - Frontal carinae prominent - Ocelli often very distinct (top of head) - Long maxillary palps - Large eyes - Pronotum often lower than mesonotum - Depression between pronotum and mesonotum - Commonly, red head and mesosoma, and black gaster, also solid colors (yellow, brown) Habitat and ecology: - Abundant at higher elevations - Pine forests in USA and Mexico - Cool and moist habitats (deserts) - Nests can be large or small - Predaceous 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
Genus Lasius Propodeum 6 segments Maxillary and Labial palps Descriptive Characteristics: -Maxillary palps with 6 segments -Maxillary palps very obvious -Propodeum rectangular, usually pointed Habitat and ecology: - Pine forests, high elevation grasslands - Also found in deserts - Common in Mexico and USA Behavior: Slow, not aggressive Note: 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.
Genus Myrmecocystus (Honey Pot Ants) Last 3 segments of the maxillary palp Myrmecocystus mexicanus Descriptive Characteristics: -Maxillary palp: Segment # 4 very long, count from end - Psammophore sometimes present Habitat and ecology: - Common in deserts in SW ecosystems, - 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
Genus Paratrechina 12 segments Dark coarse hairs Descriptive Characteristics: -12 segmented antennae -Dark coarse hairs on pronotum and mesonotum - viewed from directly above, mesosoma lacking hourglass-like shape - Eyes located towards the mid-front of the head Habitat: - Temperate North America and south, common throughout southern USA and Mexico. - Found under rocks - 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
Genus Polyergus Petiole Prominent Long mandibles Head of a worker of Polyergus breviceps Descriptive Characteristics: - Mandibles long, sickle shaped - Red-brown in color - Petiole with prominent rounded node Habitat: - Temperate and mountainous North America south into Mexican highlands - Cannot feed themselves, need Formica slaves Behavior - 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.
Genus Prenolepis Alitrunk hour-glass shape Hour glass-like shape Descriptive Characteristics: - Mesonotum, if viewed from, above very slender, the mesosoma has hourglass-like shape - Golden or brownish Habitat and ecology: - Temperate and mountainous USA and in Mexican highlands = 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.
Rare genera: Genus Acropyga Descriptive Characteristics: - Small, clear yellow ants, tiny ants. - Elongate scape. - Maxillary palps with 2 segments. - Labial palps with 3 segments. Habitat and ecology: - Subterranean - Tend coccids on roots - Rarely collected, but probably common 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.
Genus Anoplolepis Descriptive Characteristics: - Scape very long - Medium sized ants - Maxillary palps long, with 4 segments - Labial palps with 4 segments Habitat and ecology: - Usually a pest species in urban habitats 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.
Genus Myrmelachista Descriptive Characteristics: - Antenna with 9 or 10 segments - Club with 3 segments Habitat and ecology: - Nests in twigs. Behavior -Hide and rescue brood. Note: . This genus is very similar to Brachymyrmex, but has an antennal club.
Genus Plagiolepis Descriptive Characteristics: -Behavior Note: . Habitat:
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