Common name: 'Brown Sugar Ant'
These ants have a distinct minor and major worker caste. The minor workers which make up the bulk of the colony are black with varying degrees of brown markings and about 5 to 7 mm in length. The major workers are 7 to 9 mm long and are easily distinguishable by their larger head which is a distinct red / orange colour. They have no sting and although they are capable of giving a bite it is not very painful.
They are a nocturnal species preferring to do their foraging at night, although in times of food shortage and on overcast days they can be found outside during daylight hours. Because they forage at night they are able to establish colonies near human habitation and in cultivated areas which many of the larger day active species cannot do. This is because such areas are usually quiet at night and their presence is often not noticed. Being mostly night active also helps protect them from daytime predators such as birds and lizards.
They forage both over the ground and up in the trees often traveling long distances to food sources. They are particularly fond of sugary excretions - hence their common name of 'sugar ants'. Where these sources of food such as aphis are far from the colony they will make temporary camp sites with a few hundred workers near the source - enabling them to call on reserves quickly if the food supply is threatened. They also feed on a wide variety of other foods including dead insects and will strip the meat from dead animals such as lizards and even dead birds. Large colonies will work very quickly on a carcass and can leave a perfect clean skeleton overnight.
They are mostly opportune nesters preferring to form colonies in ready made cavities, as opposed to constructing a nest in the ground. They will happily form nests in a wide variety of locations such as hollow bricks, under plant pots and planks of wood, in dead bamboo stems and even inside door locks! They will however also dig out a nest if necessary. Because of their nesting habits they will readily take to almost any kind of artificial nest you provide.
The queens are distinctly larger than the worker caste at around 12 to 14 mm and can vary in colour, not only between different nests but also within the same nest. Some queens have distinct red heads and abdomens while others seem to be nearly all black in coloration.
This species is polygynous and as the colonies increase in size they will allow newly mated queens to enter the nest. Once the new queens have been fully accepted they will frequently move around at night between the different nest sites.
As the colonies increase in size they will colonize new areas and create sub nests in any convenient nesting location. With this method this species is one of those that without any limiting factors can just carry on expanding into enormous super colonies. One colony I have been observing in the wild for several years has grown to such a size that their foraging activity at night resembles the European wood ant with thousands of workers foraging on long well-worn trails. This colony is estimated to have about 40-50 individual queens and over a hundred thousand workers, being the dominant species over a large area of land.
They are able to raise a large amount of brood in ratio to the number of workers and in optimum conditions they can multiply very quickly. The eggs hatch in 11 days and the larvae pupate 10 days later, with the adults emerging after 7 more days - giving a 28 day brood cycle.
In their natural habitat in Northern Thailand the alates are produced from the brood that is raised after the cooler winter period and when the food supply increases in the spring. Alates start to emerge in March – May. The males are about the size of the workers and mating occurs in the air. Flights occur in the early evening on windless, humid days, usually during June.
In captivity males will regularly be produced in spring by most colonies but females are only produced in very strong colonies which have an unlimited wide variety of food available. It is very unusual for colonies in captivity to raise female alates. If the colony is small it will still produce the occasional males which are then usually killed off by the workers. These males mature from unfertilized eggs laid by workers and their presence should not be mistaken as being a sign that the queen is not fertilized. Usually eggs laid by the workers are eaten or fed to other larvae but in the spring as food is so readily available many of the workers eggs are left to mature and produce males.
The queens are quite capable of establishing their own colony and after their flights the newly mated queens will often spend several days wandering around looking for a suitable location to create a nest. Once they have chosen a place to raise their first brood they will seal themselves in and do not leave the foundation chamber.
The majors / soldiers are produced as the colony increases in size and these act as true soldiers - guarding the nest entrance and being the first ones to charge out when the nest is disturbed. When the colony is threatened these soldiers can become very aggressive and will selflessly defend the colony. They will not tolerate other ant species in their territory and will vigorously defend their foraging area and food sources. The soldiers will immediately attack any potential intruders and will even attack much larger aggressive ants such as Oecophylla. Although they will suffer heavy losses against these larger species the constant aggression shown by the soldiers of the Camponotus will irritate the larger species, eventually driving them away to a quieter nesting place.
Some other species however do seem to be able to co-exist within their territory. Species which are strictly day active and do not forage at night such as Polyrhachis australis do not conflict with them and other species that have very small active workers such as Tapinoma melanocephalum also seem to be able to survive near their colonies. These are small, very fast moving and utilize the waste from the Camponotus as a food source.
The workers of this species seem to be quite intelligent and thoughtful in their actions almost to the point of reasoning.
Although they will follow scent trails they are also able to make it known amongst the workforce where food is that they cannot lay a scent trail to. I have actually observed them swimming across shallow water to get to a food source.
They are able to withstand a wider range of habitat conditions than many of the other tropical species offered, quickly adapting to most types of artificial nest and they will often move into a new nest within a few hours of arrival.
An ideal temperature to keep this species would be between 25–28 degrees Centigrade. They are however quite tolerant of lower temperatures and in their natural habitat in the winter months the night temperatures frequently fall to around 10-15 degrees Celsius. Several hobbyists have successfully kept them at normal room temperature without any additional heating - although in this environment a form of spot heating near the nest will help ensure rapid brood development.
Humidity does not seem to be overly important as in the wild colonies can be found in both damp and very dry locations.
In captivity they should always have a supply of sugar water which is their staple diet. Other food offered should include dead insects such as spiders, crickets and mealworms. They will also take cake, tuna and the brood of other ants.
To observe their night time activity a red / orange night light can be suspended above the nest. This allows you to observe the ants going about their nocturnal tasks without having to disturbing them.
This species is also capable of acoustical communication although this is often never noticed because of the type of artificial nest used to house them. On a solid non resonating substrate they are not able to produce any sound; however on a medium such as dry leaves the ants can produce an audible drumming noise. This is caused by the ants knocking their heads / bodies against the substratum and is used primarily for an alarm signal but also as a sign that food has been found - with the vibrations being quickly picked up by any other nearby workers.
In large colonies in the wild this drumming can create a feeding / attack frenzy with hundreds of workers immediately coming to the area to see what the problem is. In captivity the addition of a few dry leaves or small pieces of crumpled newspaper to their foraging area will allow them to exhibit this behaviour.
Summery: We highly recommend this species as the ideal first species for those just starting to keep tropical ants. They are one of the easiest exotic species to start with and are very easy to keep in captivity. They are active throughout the year and do not have a sting - making them suitable for younger hobbyists.