Biology

Household Sugar Ant, Camponotus humilior Inside the nest of the Household Sugar Ant, Camponotus humilior. The worker ants (sterile females) are tending the legless larvae. The larger white ‘bags’ are cocoons that each contain a pupa. Camponotus gasseri Some ants, like Camponotus gasseri, nest in cavities in tree branches. This species is dimorphic with two distinct sizes of workers. An alate or winged queen of Carebara sp. An alate or winged queen of Carebara sp. within the nest. Certain weather conditions will trigger the colony to release these winged queens and winged males. The queens mate and then search for a good spot to establish a new colony. Iridomyrmex worker An Iridomyrmex worker gathers sugary honeydew secreted by a scale insect. Many ant species collect honeydew from sap-sucking insects.

Ants are social insects, living in long-term colonies that survive from year to year. Most of the ants in a colony are workers. They are sterile females that collect food, tend the young and maintain and defend the nest. The ants that people see running around are almost always workers. A typical ant colony contains a single queen, the only individual that lays eggs. However, the colonies of some ant species have a few to many queens.

Ant eggs hatch into pale, legless, grub-like larvae that are fed and tended by the workers. When fully grown, ant larvae transform into non-feeding pupae that are either naked or enclosed in a cocoon. New worker ants emerge from the pupae. Worker ants are fully grown; small ants do not grow into large ants.

Depending on the species, the worker ants in a colony may:

  • be all about the same size (monomorphic, eg. Green-head Ants or Spiny Ants).
  • come in a range of sizes from small to large (polymorphic, eg. some Sugar Ants).
  • come in two distinct sizes, small minors and large majors, with no intermediates (dimorphic, eg. Coastal Brown Ants).

At certain times of the year ant colonies produce winged ants called alates. These are reproductive females and males. They remain inside the nest until the right weather conditions trigger them to emerge. Nests of the same ant species in an area release alates at the same time. The winged males and females swarm and mate. The males are short-lived and die within a few days. Females (future queens) fly off to find a suitable nesting site, shed their wings and establish a new colony.

 

Many species of ants nest within the ground. Nest entrances may be in the open or located under rocks and logs. A few species are almost completely subterranean, the workers never foraging above ground. In dense forests many ants nest in the deep layer of leaf litter and many make nests in rotten wood. Other ants build their nests well above ground, using hollows in the branches and trunks of trees or creating their own nest cavities by webbing leaves together with silk produced by their larvae.

Most ants are predators or scavengers gathering a wide variety of different foods. The insect or breadcrumb that you see an ant dragging back to the nest will be fed to the larvae. In most ants the larvae only eat solid food. The worker ants themselves are liquid feeders, gathering energy rich sugary liquids such as nectar and honeydew (a sweet liquid secreted by sap-sucking insects).

 

Some ant species are more specialised, hunting a particular type of prey, gathering only seeds, or feeding just on sugary honeydew. Some ant species are so dependent on honeydew that they virtually farm the sap-sucking insects, often building protective shelters over them. Some ants even keep the insects in their nests during the night and take them out to feed on plants during the day.

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