Pheidole

This is one of the most common groups of ants in warmer regions of the world. Most species nest in soil with a low mound of loose dirt around the entrance. These nests 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 or in plant roots while a few 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. Well defined foraging trails are sometimes established between nests and food sources. A wide range of food is taken as these ants are seed harvesters as well as general predators and scavengers; they also collect honeydew from Hemiptera and plant fluids including nector. When feeding on seeds they can take large numbers very rapidly. Division of labor is well developed in these ants. Major workers, which make up about 10% of all workers, rarely venture far from the nest and are involved with defence as well as dissecting large food items. Minor workers undertake most of the foraging and nest construction. P. megacephala is a pest introduced to many areas. 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. A few species are known to be inquilines in the nests of other Pheidole species.



Minor worker of P. vigilans from Norfolk Island.



Major worker of P. vigilans from Norfolk Island.

Identification
The antennae are 12 segmented (including the scape) and have a 3 segmented club. 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. Most species with distinct majors and minors but without intermediates (dimorphic), but a few species have intermediates as well (polymorphic).

Pheidole is most similar to Aphaenogaster and Pheidologeton. They can be separated from Aphaenogaster by the 3 segmented 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).

Distribution and Habitats
Australian distribution

Regional Species Lists

 * Australia

Keys to Species

 * Australia