At a partnership property in Tasmania's northern midlands I came across a White Gum with ants just erupting out of the crevices. It's a common enough phenomenon at this time of year, but no less fascinating to notice.
Flying ants are common in summer and sometimes you'll see winged ants being shoved out of an established colony by wingless workers - that's what I was witnessing.
Colonies are established by a sexually mature female or 'Queen', which would have originally been winged. After mating she sheds her wings and re-uses the wing muscles as nutrients as she establishes her colony.
Very few Queens successfully survive to establish a colony. If they do, wingless workers are bred, perhaps for several years, until the colony is well -established and ready to put energy back into reproductive forms - some more winged ants (potential Queens) and more mature males.
The gaps in the White Gum (as Eucalyptus viminalis is known in Tasmania) that they're coming out of are where branches have fallen off or occasionally the bark has split from the very dry conditions last summer, allowing pests and diseases to get in under the bark.
Usually after heavy rain winged ants can emerge in swarms from whatever cracks, crevices or burrows they have established in.
Often they can emerge from multiple colonies at the same time when conditions are right and their mating takes place often over a single day. Males then die and females disperse to try to establish new colonies.
Some ants engage in 'hilltopping', which is gathering at prominent high points of a landscape to search for mates. A large tree, such as this White Gum, is ideal.
Ants on the move. 
