Ants: Family Formicidae

Ants are one of the most successful and ecologically important groups of terrestrial insects. They have colonised all terrestrial habitats throughout the world except the polar regions and highest mountaintops.

Ants can be found anywhere from coastal mangroves to urban backyards and inside our homes. Their success, in part, is because of their ability to communicate with each other. They have the most complex form of chemical communication in the animal kingdom and together they accomplish tasks beyond any individual insect.

Ants are formidable opponents and defend their foraging area from other animals. They can overwhelm by sheer weight of numbers and have offensive armoury that may include fierce jaws and potent stings.

Features of ants:

• Ants are social insects. They exist in colonies that work together to gather food, rear young and defend the nest.
• Nests contain eggs, larvae and pupae and different types (or castes) of ants.
• Colony sizes range from a few individuals to tens of thousands. Each colony is made up of a queen, different-sized workers and a number of other castes at different stages of the colony cycle.
• The most commonly seen caste are workers.
• Winged ants leave the nest to mate and found new colonies in late summer and spring, often after rain. Many are eaten by birds and other predators.
• Ants are probably the most common insects encountered by humans.
• There are around 15,000 different species of ants worldwide.
• There are 1,275 Australian ant species described, but this could double with further research.
• Most species of Australian ants are found only in Australia.
• Many plants and other insects have evolved relationships with ants, even to the point where ants are a necessary part of their life cycle.
• Some birds place ants on their bodies to remove parasites. This is known as anting.

What do ants look like?

Body:

• Elongate and constricted at 'waist'.
• Abdomen swollen, sometimes greatly.
• One or two knobs at waist. These knobs sometimes are reduced or flattened.
• Appears hard.

Antennae:

• Thread-like and distinctly elbowed.
• Segment closest to body much longer (at least five times as long) than any of the remaining segments.

Eyes:

• Range from large and well separated to small.
• Nocturnal or litter dwelling species may have reduced eyes or no eyes at all.

Mouthparts:

• For chewing or munching.
• Held in front at rest.

Wings

• Two pairs if present.
• Only reproductives have wings, which are sometimes lost after mating and before constructing the founder nest.
• Both pairs membranous, clear and with few veins and cells.
• At rest wings are held flat to the body and almost entirely overlapping.

Limbs:

• Six slender legs.

Abdomen tip:

• Cerci (tails) absent but some have a prominent stinger.

Where are ants normally found?

• They construct nests that are highly variable in structure and complexity. They can consist of simple chambers under rocks and other objects, through to extensive networks of chambers extending deep into the soil.
• Some have a nomadic lifestyle, often relocating temporary nests found amongst leaf litter.
• In the trees they tend to use and partly modify existing burrows and crevices, such as beetle holes. Some specialised ants construct nests by joining leaves with silk.
• Often found in and around houses.

What do ants do?

• They are highly social, that is, they form colonies where individuals share the responsibility of providing care for the young.
• They often have distinct castes such as queens and kings, workers and soldiers, which have different roles in the nest. Workers are generally unable to reproduce, with only queens laying eggs.
• Depending on the species they will forage in groups, or sometimes as individuals.
• When disturbed workers tend to runaway from danger. Soldiers often confront the disturbance and may react by biting, squirting acidic chemicals or stinging.
• They often move in a zigzag motion searching for food items. Some species of ants run in lines, often on paths.
• Adult ants feed on liquids but larvae will feed on processed solids. The majority of the liquid diet comes from sugar-rich secretions from plants, other invertebrates or from their larvae that accept plant and animal tissue, which is then regurgitated and presented in a liquefied form to the adults. Many ant communities form special partnerships with plants and other insects. The ants protect, tend or even feed their partners, in return they are supplied with sugar-rich secretions.
• They are important for dispersing seed and modifying soil and plant community structures.
• They are active during the day or night but some may have a preference for certain time periods.

Atypical ants

• Some groups of Australian ants such as Tapinoma and Technomyrmex do not have knobs at the waist. They are however very ant like and very unlikely to be mistaken with anything else.

What looks similar?

• A number of wasp families contain species that are excellent ant mimics. Good examples are the velvet ants (Order Hymenoptera, family Mutillidae) and the flower wasps (family Tiphiidae). Both families have wingless females that look like ants. Wasps can be separated from ants by the lack of knobs at the waist and no distinctly elbowed antenna with long first segments. However, some mimics are amazingly similar to ants and may appear to have these features. These can be very difficult to distinguish even for the experts, in this instance they maybe distinguished by the lack of particular gland structures and the presence of felt lines along the abdomen. Unfortunately these attributes can only be observed using a microscope.
• Some spiders look and behave like ants. On closer examination they maybe distinguished from ants by having only two major body regions and eight legs.
• Some true bugs are fantastic mimics of ants but generally they can be separated by sucking tube mouthparts, a lack of constriction at waist and no elbowed antennae. Some may have a pseudo-constriction at the waist, in this case they do not display the one or two knobs.