AW Insect Book: Sawflies, Wasps, Bees & Ants (Hymenoptera)

[Toko]

Weaver Ant, Tailor Ant Oecophylla longinoda
Superfamily: Vespoidea. Family: Formicidae. Subfamily: Formicinae. Tribe: Oecophyllini

© Dewi
KwaZulu-Natal, Kosi Forest lodge

Description
Medium-sized (body length of workers 7-11 mm). Rust-coloured, elongated; long antenna, with the first segment red; head large; petiole scale long, gaster small.Oecophylla longinoda possesses dimorphic workers and therefore three distinct female castes, the queen, major worker, and minor worker.
These ants range from orange to dark brown in color. Erect hairs cover the surface of the gaster while a finer pubescence encompasses the rest of its body. The eyes are well developed with eyespots. The clypeus, the large shield-like plate on the front of its head, is large and convex with the outer edges overhanging the basal borders of the mandibles. It has 12-segmented antennae with the first segment of the antennae longer than the second and the third put together. Its mandibles are extended, and have triangular elongated teeth that cross one another when at rest. The thorax is very constricted in the mesonotal region. The petiole between the thorax and abdomen is thin in dorsal view, but looks low and rounded in the side view. The gaster has a visible acidopore. On the ants' feet, there are powerful suction pads called arolia, allowing this ant to maintain heavier loads than other ants. Another important characteristic of the weaver ant is the presence of the rectal gland and the sternal gland, both of which are located near the anus and are used to secrete chemicals to recruit nestmates when circumstances arise that require the attention of a group of ants.

Distribution
Forested regions of tropical Africa.

Habitat
Weaver ants are arboreal, living in heavily forested areas. The ants inhabit tree canopies in which they build nests out of living leaves. One colony may occupy several trees at one time.

Biology
The African weaver ants are primarily insectivorous, attacking and eating any ants or other insects that invade their nest. They will even attack and eat weaver ants from other colonies.
They make nests in trees made of leaves stitched together using the silk produced by their larvae.
Weaver ants build their nests from the leaves of trees, bending the leaves into place and then binding them together with silk produced by larvae. When building a new nest, ants begin by walking along the edges of leaves, occasionally pulling up on the edges to test the flexibility of the leaf. If the ant succeeds in turning up the leaf even the slightest bit, other ants join in forming chains of their bodies. By grasping the thoracic region of another ant, an ant chain long enough to extend between the ends of a leaf can be made. The ants in the chain then pull the ends of the leaves together until they are next to each other. Then other ants seal the leaves together by applying the silk from larvae that are in their final instar. Holding the larva and touching it with antennae in a certain way signals the larva to produce silk, and the ant can weave the two leaves together. It is in this last of at least three larval instars that larvae might be recruited to contribute silk to the building of nests. (This is child labor ) The larvae do not build cocoons because of the protection afforded them by the nest and because they have given up their silk for nest construction. By building nests in this way, and having an unlimited number of nests per colony, weaver ants have no spatial limitations for their colony, and so can occupy several trees at one time. With this much room, it is not uncommon for single colonies to have populations of a half million or more ants.

Links: The Ants of Africa

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Spiny Ant Polyrhachis schistacea
Superfamily: Vespoidea. Family: Formicidae. Subfamily: Formicinae. Tribe: Camponotini

© BluTuna
Kruger National Park, Timbavati

Polyrhachis is one of the largest and most diverse ant genera in the old world tropics. These attractive insects are closely related to the cosmopolitan genus Camponotus but are often ornamented with protective spines. Polyrhachis is found in many different habitat types and show a wide variety of nesting behaviors.

Polyrhachis schistacea nest in the soil and often build a structure of grass round the nest entrance, which sometimes can grow to be a c 25 cm diameter dome of woven grass with multiple grass-lined entrances.

Links:
The Ants of Africa Polyrhachis schistacea
The Ants of Africa SUBFAMILY FORMICINAE - Genus Polyrhachis subgenus Myrma

© BluTuna
Kruger National Park, Crocodile Bridge

[BluTuna]

Slender Ant Tetraponera natalensis group
Superfamily: Vespoidea. Family: Formicidae. Subfamily: Pseudomyrmecinae

© BluTuna

© BluTuna
Garden in Johannesburg

Tetraponera is is a pseudomyrmecine genus of conspicuous, often arboreal ants in the warmer regions of Africa, Asia, and Australia. There are five african monophyletic species groups in the ant genus Tetraponera.
Slender ants are medium-sized (body length of workers 4-10 mm).
Workers are long, slender, short-legged, reddish brown, with relatively large eyes, and last part of thorax unarmed. Short mandibles, usually with 3-4 (rarely 5-6) teeth on masticatory margin and 0 - 2 denticles on basal margin; compound eye large and oval, width two-thirds or more of length.
Males and queens also long and thin.
Nest in hollow twigs, reeds or thorns.

Life cycle and castes:
Tetraponera like most ants have one or a few queens that are the only females to reproduce in a colony. The sterile workers are all females that forage for food and defend the colony. Workers have a large, strongly developed, painful sting used to capture prey and defend colony. Males are produced only during certain times of the year and disperse to mate with virgins queens from other colonies. Since ants are haplodiploid they can control what sex their offspring will be; an unfertilised egg will become a male while a fertilised egg will be female. This reliably restricts the production of male alates to the species's mating season, when the winged virgin queens and males fly from their home colonies to mate and start new colonies.
The eggs produced by the queen hatch into larvae which are cared for inside the colony, protected from any predators by the workers. The amount of care each female larva receives determines its fate as a worker or a new queen; all males are drones. When a new colony is formed eggs are initially produced at a low rate, but this quickly increases in the second to fourth years, ensure that there are enough workers to protect and provide for the growing colony.

Tetraponera natalensis-group:
This is a distinctive group of species, easily recognized in the worker and queen by the sharp margination on the pronotum (extending to the propodeum and petiole) combined with a subopaque and densely punctulate-coriarious integument. The worker has a characteristic form of the mesonotum: semicircular in dorsal view, much wider than long, and with a straight posterior margin. The median notch on the posteroventral margin of the petiole is also unique to the group. Integument densely punctulate to punctulate-coriarious, the sculpture giving a subopaque (matte) appearance to most of body.
Distribution: Africa, northwestern Madagascar.

Links:
Ants of Africa
The ant genus Tetraponera in the Afrotropical region: synopsis of species groups and revision of the T. ambigua-group (Hymenoptera: Formicidae).

[ExFmem]

Slender Ant Tetraponera sp., possibly T. natalensis group
Superfamily: Vespoidea. Family: Formicidae. Subfamily: Pseudomyrmecinae

© ExFmem
Kruger National Park (September)

[ExFmem]

Subfamily Myrmicinae

Distribution of Myrmicines
Myrmicines occur throughout the world in all major habitats (except arctic and antarctic regions). They are the largest subfamily of ants with over 6700 species and subspecies and 155 genera.

Identification of Myrmicines
Morphologically, these ants are very diverse. Many groups are highly modified with unusual mandibles, elongate spines, elaborate hairs or unique structures not seen in any other ants. Because of this, many genera are relatively easy to identify as they have highly distinctive features which are easily seen (given the appropriate magnification). At the same time, some genera are much less specialised or modified, and separating these from close relatives can be difficult.

The petioles of Myrmicinae consist of two nodes. Species of myrmicines are most likely to be confused with species of Leptanilla or Tetraponera because of the two segmented petiole. However, both Leptanilla and Tetraponera have the pronotum and mesonotum unfused and with a flexible joint between them, while in all myrmicines these two plates are fused into a single structure.

Myrmicine worker ants have a distinct postpetiole, i.e., abdominal segment III is notably smaller than segment IV and set off from it by a well-developed constriction; the pronotum is inflexibly fused to the rest of the mesosoma, such that the promesonotal suture is weakly impressed or absent. A functional sting is usually present. The clypeus is well-developed; as a result, the antennal sockets are well separated from the anterior margin of the head. Most myrmicine genera possess well-developed eyes and frontal lobes that partly conceal the antennal insertions.

Male myrmicines are recognizable by the anterior and posterior constrictions of abdominal segment III, forming a postpetiole, which is smaller than the fourth abdominal segment (gastral segment I); antennal insertions distant from the anterior margin of the clypeus (nearly abutting in the proceratiine genera); meso- and metatibiae never with two spurs each (two each in the pseudomyrmecinae); anterior and posterior foramena of petiole more-or-less in the same plane.

Biology
Generally, males are reproductive winged ants and so are alates, and are also called drones. Drones are the only male ants in a colony and are born from un-fertilized eggs. They take to the skies on the same day as the princesses to mate during the nuptial flight and the males die soon after mating with females. Once the female has mated, she will rake her legs forward to snap her wings off at the basal suture and find a suitable spot to begin a new colony.

Links:
http://www.antweb.org/description.do?ra ... ct=calants
http://www.antwiki.org/wiki/Myrmicinae

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Red-black Cocktail Ant Crematogaster castanea rufonigra
Superfamily Vespoidea. Family Formicidae. Subfamily Myrmicinae. Tribe Crematogastrini



© BluTuna
Kruger National Park, Tshange

Crematogaster is an ecologically diverse genus of ants found worldwide, which are characterised by a distinctive heart-shaped gaster.
Postpetiole articulated on dorsal surface of first gastral segment; the gaster in dorsal view roughly heart-shaped and capable of reflexion over the alitrunk. Petiole dorsoventrally flattened and without a node. Many species, with wholly inadequate classification. Most species are monomorphic and small (2-3 mm).
Cocktail ants are mostly arboreal, some species making their nests in hollow branches, while other cocktail ants use crevices beneath the bark.
Many cocktail ants make 'carton nests', constructed of chewed vegetable matter mixed with a secretion from the jaw glands of the worker ants. The walls are blackened by the secretion, and are paper thin, while the inside is divided into many irregular, interconnecting cells. These spherical nests may be found hanging among the branches, or lying in a tree hollow.

Identification
This subspecies of C. castanea occurs on the escarpment and in the lowveld.
4-5 mm. Head red-brown. Tarsi, antennae and gaster darker.

Links:
The Ants of Africa. SUBFAMILY MYRMICINAE - Genus Crematogaster

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Cocktail Ant Crematogaster peringueyi
Superfamily Vespoidea. Family Formicidae. Subfamily Myrmicinae

© Toko
An arborial nest made of vegetable fibres and glue with salivary secretions. Hluhluwe Game Reserve, KwaZulu-Natal

The Double-waisted ants in the very large subfamily Myrmicinae have narrow, ‘double-jointed’ waists or petioles, as a result of which some can raise their abdomens over their heads when danger threatens. Most South African species are not armed with stings although many overseas species can sting viciously. The pupae of this subfamily are always naked, i.e. the larvae do not spin cocoons. Apart from these common features, however, there is a huge variety of shape, size, habit, etc etc within the subfamily. Some are harvesters, some are fungus-growers, some may be purely carnivorous hunters. Many live in tunnels in the soil, while others build carton-like nests in bushes and trees, or live in thorns, or rotting wood. Sizes range from tiny, less than 1.5 mm, to large ants up to 10 mm; some are blind, some are monomorphic [one size of workers] while others have major workers with the most disproportionally-large heads in the business.

Crematogaster ants can be regognized by the unique articulation of the postpetiole which posteriorly is attached on the dorsal surface of the first gastral segment. The head is usually broader than long.

Description
Small (body length of workers 3-6 mm, queens 10 mm). Head, thorax, 2-segmented waist and legs reddish brown and black in workers. Workers reflex black, heart shaped, pointed abdomen over thorax when alarmed. Sting replaced by gland that secretes irritant defensive fluid.

Distribution
South Africa, Namibia

Biology
Runs in trails. Builds carton nests in bushes and trees, from vegetable fibres glued with salivary secretions. Workers tend aphids and coccids for honeydew.

Links:
The Ants of Africa
Myrmicinae: the Double-waisted ants
Crematogaster sp: Cocktail ants

[ExFmem]

Myrmicine Hotrod Ant (Male) Ocymyrmex sp.
Superfamily Vespoidea. Family: Formicidae. Subfamily: Myrmicinae

© ExFmem
Kgalagadi Transfrontier Park (October)

Male ants have confounded taxonomists for centuries, dating back to Linnaeus (1764), who described the first male ant as a wasp. When you see a winged individual, you can recognize males based on their small head and their long antennae. Males usually have more antennal segments than the females.
Male myrmicines are recognizable by the anterior and posterior constrictions of abdominal segment III, forming a postpetiole, which is smaller than the fourth abdominal segment (gastral segment I); antennal insertions distant from the anterior margin of the clypeus (nearly abutting in the proceratiine genera); meso- and metatibiae never with two spurs each (two each in the pseudomyrmecinae); anterior and posterior foramena of petiole more-or-less in the same plane.

The Genus Ocymyrmex (Hotrod ants) have a ‘beard’ or basket of bristly hairs beneath their heads, which seems to be solely used for removing sand grains from their nests. Hotrod ants make shallow, underground nests consisting of a few tunnels and chambers, and the colonies are usually quite small in number.

[Toko]

Myrmicine Hotrod Ant Ocymyrmex resekhes
Superfamily Vespoidea. Family: Formicidae. Subfamily: Myrmicinae

© ExFmem

© ExFmem

© ExFmem

© ExFmem
Kgalagadi Transfrontier Park

Description
Palp formula 3, 3 (dissection of paratypes). Median clypeal notch conspicuous, flanked by a triangular tooth-like prominence at each side. Eyes just failing to break the outline of the sides of the head in full-face view; maximum diameter of eye 0.22 x HW. Sides of head convergent posteriorly, especially behind the eyes where they round broadly and evenly into the occipital margin. Median impression of the occipital margin vestigial. In front of level of eye the sides less convex than posteriorly, only feebly divergent anteriorly. With alitrunk in profile the pronotal dorsal outline somewhat flattened, not evenly convex, ascending posteriorly to the convex mesonotum which slopes posteriorly down to the propodeum. Metapleural lobes small and rounded, but visible in profile, projecting beyond the bulge of the metapleural gland bulla. Peduncle of petiole long and narrow, tapering anteriorly, its anteroventral surface not suddenly deflected upwards close to the articulation with the alitrunk. Petiole node in profile low and rounded, in dorsal view narrow and somewhat longer than broad. Postpetiole in dorsal view longer than broad. Base of gaster in dorsal and lateral view distinctly constricted; the base of the first tergite slightly narrower than the postpetiole in dorsal view. Cephalic dorsum finely and very densely longitudinally costulate. The costulae centrally on the head running straight back towards the occiput, but those in front of the eyes oblique. The costulae themselves are somewhat irregular, not straight, but without large vermiculate areas and the head lacking areas of chaotic sculpture. Sides of pronotum weakly longitudinally costulate, remainder of side of alitrunk obliquely rugulose. Transversely arched costulae on pronotal dorsum very weak, almost obliterated in places. A small patch of longitudinal sculpture is present between the mesothoracic spiracles but behind this the dorsal alitrunk is uniformly transversely rugulose, as is the propodeal declivity. Petiole ventrally with short transverse rugulae, which also occur dorsally on the peduncle, but elsewhere on petiole sculpture is reduced to a fine granulation or superficial reticulation. Postpetiole everywhere with fine superficial sculpture everywhere. Pilosity on head and alitrunk dorsum conspicuous and dense, the dorsal alitrunk with numerous short elevated hairs between the longer main components of the pilosity. Mesopleura and metapleura densely clothed with outstanding hairs, almost with a furry appearance. Colour of head and alitrunk a very dull dark red, the gaster lighter, orange-red to yellowish.
Ocymyrmex resekhes is separated here as a sibling species of the more widely distributed Ocymyrmex flaviventris. The two are basically very similar indeed, but differ in the relative length of the petiolar peduncle, shape of the peduncle anteriorly, and width of the petiole node. In resekhes the petiolar peduncle is long and narrow in profile, tapering more or less evenly anteriorly to the junction with the alitrunk. The anteroventral portion of the peduncle is not suddenly deflected upwards near to the articulation with the alitrunk. In dorsal view the petiole node tends to be elongate and narrow, usually as long as broad or even slightly longer than broad. A few specimens have the node broader than long, but this widening is not nearly so pronounced as in flaviventris. The petiole peduncle in O. flaviventris is short and stout in profile and the anteroventral margin of the peduncle is suddenly deflected upwards near the articulation with the alitrunk. Sometimes the ventral margin of the peduncle immediately behind this is convex, enhancing the effect. The petiole node in dorsal view is always very conspicuously much broader than long. Some variations in shape occur in the outline profiles of the petiole in both species. Finally, workers of flaviventris average smaller than those of resekhes, and apparently always have shorter scapes.

Links:
http://antsofafrica.org/ant_species_201 ... myrmex.htm
http://antsofafrica.org/ant_species_201 ... sh1989.jpg
http://antsofafrica.org/ant_species_201 ... ns6438.pdf
https://myrmecologicalnews.org/cms/inde ... format=raw

[ExFmem]

Big-headed Ant, Brown House Ant Pheidole megacephala
Superfamily Vespoidea. Family Formicidae. Subfamily Myrmicinae

© ExFmem
Kruger National Park

Description
Most species of the genus Pheidole, including P. megacephala, have 12-segmented antennae, the terminal three segments of which are enlarged to form a discrete three-segmented club, and a discrete soldier or major worker caste with an allometrically enlarged head. The most distinctive feature of this species is the grossly swollen postpetiole.

Minor worker: head length 0.59 mm, head width 0.53 mm, scape (first long segment of the antenna) length 0.58 mm, length (distance from anterodorsal margin of pronotum to posterior-most extension of metapleural lobes) 0.72 mm (n=1). Head rounded behind; promesonotum evenly arched, mesonotal suture very weak; propodeal spines small but distinct; face and pronotum smooth and shining, katepisternum and lateral propodeum feebly foveolate; postpetiole grossly swollen; dorsal pilosity abundant, long, flexuous, some setae on mesosomal dorsum branched near apex, branches minute; color brown.

Major worker: head length 1.22 mm, head width 1.21 mm, scape length 0.65 mm. Face between frontal carinae with parallel longitudinal carinae, space between eyes and frontal carinae punctatorugose overlain with parallel longitudinal carinae, rest of face smooth and shiny; hypostomal margin nearly flat, with pair of very small, low tubercles, located about one-third of the distance from the midline to recessed teeth flanking mandibles (superficially looks like there are no hypostomal teeth); dorsal pilosity abundant; sparse subdecumbent setae projecting from the sides of the head in face view.

Distribution
P. megacephala was described from a specimen from the island of Mauritius by the entomologist, Johan Christian Fabricius in 1793, although a previous record exists for Egypt 18 years earlier. Regardless of its original distribution, bigheaded ants have since spread to many tropical and subtropical parts of the world.

Biology
Bigheaded ants nest in colonies underground. These soil-nesting ants are sometimes confused with subterranean termites because they may create debris-covered foraging tubes that are somewhat similar, albeit much more fragile, than termite tubes. More often these ants leave piles of loose sandy soil.

Colonies can have several queens and super-colonies can be formed by budding, when a queen and workers leave the original nest and set up a new colony nearby without swarming. Nuptial flights of winged ants take place during the winter and spring and fertilized queens shed their wings and find a suitable site to found a new colony where they start laying eggs. Each queen lays up to 290 eggs per month. The eggs hatch after two to four weeks and the legless white larvae, which are fed by the workers, pupate about a month later. The adult workers emerge ten to twenty days after that.

The bigheaded ants feed on dead insects, small invertebrates and honeydew excreted by insects such as aphids, soft scale insects, mealybugs, whiteflies and plant hoppers.

Economic Impact
P. megacephala can have beneficial effects by attacking other insect pests, such as the lilly pilly psyllid, egg masses of the southern green stink bug, Nezara viridula, in Hawaiian macadamia orchards, eggs of Chilo sacchariphagus, a key pest of sugarcane on Reunion Island, and lepidopteran larvae on grain sorghum fields in South Africa.

Negative economic impacts are primarily due to its interactions with honeydew-producing Hemiptera on crops, such as the plant hopper Hilda patruelis (seen in this photo) on groundnut crops and Ficus sp. In general, the workers increase the abundance of Hemiptera by decreasing the effectiveness of the predators and parasitoids and interfering with biological control efforts. Often it is not the direct feeding impact of the Hemiptera that causes economic losses, but rather their transmission of plant viruses and other diseases.

In South Africa, it is also a widespread pest associated with the increased abundance of Coccoidea on citrus.

They can also have a negative impact by displacing beneficial ants, as they highly invasive and can displace native ants, although the degree of invasiveness varies geographically.

It has been nominated as one of the hundred "World's Worst" invaders.

Links:
The Ants of Africa
http://www.plantwise.org/KnowledgeBank/ ... dsid=40133
http://entnemdept.ufl.edu/creatures/urb ... ed_ant.htm
http://antsofthecape.blogspot.de/p/myrm ... -ants.html
https://books.google.de/books?id=jaswDw ... ca&f=false