Biology
This is one of the most common groups of ants in Australia and they can be encountered almost everywhere and at any time.  Most species form nests in the soil with a low mound of loose dirt around the entrance.  These mounds are often very active with many workers carrying soil from the nest and foraging in the immediate vicinity.  This can makes nests highly visible.  Other species nest under rocks and a few species are known to occasionally nest arboreally.  Some rainforest species nest in rotten wood on the ground.  Foraging is most common on the ground and large numbers of workers can be found at highly desirable food sources such as honey baits.  In the tropics most foraging takes place during the late afternoon and throughout the night while in cooler regions foraging occurs at all times of the day and night.  A wide range of food is taken as these ants are general predators and scavengers.  They will also feed on seeds and can take large numbers very rapidly (Briese and Macauley 1981, Clayton-Greene and Ashton 1990).  The introduced species P. megacephala is a pest common along the east and west coasts and in the Darwin region.  It can pose a serious threat to local invertebrate communities as it will severely reduce or eliminate natives insects, especially other ants, with which it comes in contact.
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Distribution and Habitats
Pheidole is the second largest genus of ants in the world with 898 species and subspecies with an additional 3 species known from fossil records.  They are found world wide.  About 53 species and subspecies are known from Australia and these can be found throughout the continent in all habitats (see map).
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Identification Notes
The antennae are 12 segmented (including the scape) and have a 3 segmented club (Figs 1, 5, 9).  In side view the propodeum is depressed below the level of the pronotum and forward section of the mesonotum, and these two regions are connected by the steeply sloping rear section of the mesonotum (Figs 2a, 4, 6, 8, 10).  Workers with distinct majors and minors but without intermediates (dimorphic) (compare Figs 3 and 4 with Figs 5 and 6, and Figs 7 and 8 with Figs 9 and 10).

Pheidole is most similar to Aphaenogaster and Pheidologeton.  They can be separated from Aphaenogaster by the 3 segmented (Fig. 1a) rather than 4 segmented club and generally smaller body size (often under 3.5 mm long), and from Pheidologeton by the 12 segmented antennae with a 3 segmented club (antennae 11 segmented with a 2 segmented club in Pheidologeton).  Additionally, in Aphaenogaster all workers are approximately the same size (they are monomorphic) while in Pheidologeton there is continuous size variation between major and minor workers (they are polymorphic).
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Many Pheidole species collect seeds as food for their larvae. When empty, the seed coats are deposited outside the nest near the entrance, often forming distinctive piles (nest entrance at centre-right). (Photo by Steve Shattuck.)

This worker is removing an empty grass seed from the nest (dragging it backwards from the entrance). This refuse will be placed on the nest's midden pile a few cm away. (Photo by Steve Shattuck.)

While Pheidole workers are well known for harvesting seeds, they are also general predators and will take a wide range of food items, such as this terrestrial amphipod (photo by Steve Shattuck).

Pheidole Westwood 1841:87. Type species: Atta providens Sykes, by monotypy.

Taxonomic Catalogue

Go to the Taxonomic Catalogue of Species.

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Literature Cited / Additional Reading

Briese, D. T., Macauley, B. J. 1981. Food collection within an ant community in semi-arid Australia, with special reference to seed harvesters. Aust. J. Ecol. 6:1-19.
Clayton-Greene, K. A., Ashton, D. H. 1990. The dynamics of Callitris columellaris/Eucalyptus albens communities along the Snowy River and its tributaries in South-eastern Australia. Aust. J. Bot. 38:403-432.
Westwood, J.O. 1841. Observations on the genus Typhlopone, with descriptions of several exotic species of ants. Ann. Mag. Nat. Hist. (1)6: 81-89.

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