We previously called this species D. scalpratum, but on further investigation have decided its correct name is D. violaceum.
These are similar in form to Diacamma rugosum but much larger. The workers measure about 1.5 cm from their mandibles to the tip of their abdomen. The third photograph above shows their comparative size to the well-known Diacamma rugosum.
There is no queen in the colony but a mated worker called a 'gamergate' lays the eggs. The brood seems to be raised in cycles with the gamergate laying eggs for about two weeks, then allowing these to mature into new workers, before starting to lay again. Once laid the eggs are continually carried in the jaws of the workers. When the larvae emerge, they are very active and can frequently be seen waving their front half around looking for food. When the larvae are mature, they spin a thick black cocoon.
Curious wasp-like males seem to be produced intermittently throughout the year and are always found near the entrances of the nests. These leave the nests in the early morning and seek out other colonies where they will mate with any receptive workers.
In the wild, this species inhabits the depths of undisturbed forests. Once the forest habitat becomes disturbed, they will move away. Their typical habitat is lowland dipterocarp forest which has a long dry season often lasting 4 months when there is little if any rain. In northern Thailand, during the dry season, the trees in these forests shed their leaves leaving a covering of leaf litter over the forest floor. During this time if you stand quietly, you can actually hear these ants walking over the dry leaves!
They have good eyesight and can sense vibrations and will freeze on the approach of a larger animal making them very difficult to detect. This action helps protect them from larger predators. They are also armed with a painful sting which is similar to a wasp sting, but the effect caused by this only lasts for a very short time. The sting is used to subdue prey, and as a shock tactic if anything grabs the ant, with the sudden intense pain causing the potential predator to drop the ant.
Their nests are usually located near old tree stumps and constructed amongst inter-tangled roots. There is a single entrance that is surrounded by an assortment of small twigs and leaves, leading to two or three large chambers at a depth of about 20 - 30 cm.
Colony sizes seem to vary from about 50 to 150 workers. Above this size, the colony will divide. Colonies are very territorial and workers will vigorously defend their hunting area against other violaceum colonies, immediately attacking any alien foraging workers. However, they tend to ignore many smaller species of ants simply walking over them.
They seem to be equally active both day and night when they slowly wander around looking for anything edible. Once suitable prey is found it is immediately pounced on, stung, and carried away. The workers forage solitarily when far from their nest but when they bring the prey back often two or three workers will help the returning forager as it approaches the nest. Excess food is stored in the nest for several days to be used on days when the weather inhibits them from leaving the nest or when other food cannot be found.
They will forage for and take all kinds of food. To date, I have fed them a wide variety of dead and live insects, dog biscuits, small pieces of raw meat, termites, tuna, and other ant’s brood.
They are voracious aggressive hunters and can easily overpower larger insects such as honeybees. When they encounter another ant species with food, they will do their best to wrestle the food from them. They can also with care be taught to take food from your hand.
They seem to be quite easy to keep in captivity if they are given as large an enclosure as possible allowing them plenty of room to forage. In the wild, each colony hunts in and defends an area about fifteen meters from its nest. This equates to a hunting area for each nest of around 700 square meters. In comparison, a large 120 cm x 45 cm glass tank has a surface area of about half a square meter. Please do not try and keep them in an enclosed setup with only a small feeding chamber.
The ideal setup is a large terrarium with a shallow humus base medium, covered with a layer of dead leaves and landscaped with several small tree branches and some moss/plants.
Summary: A very large and impressive ant that adapts well to captivity, but because of its size requires a large habitat enclosure.
Note: Caution is required as they have a painful sting.