Maybe you’ve heard of it: keeping ants as pets! Keeping an ant colony is interesting and fun because of the amazing ability of the ant colony to function as a unit. Setting up an ant colony enclosure, called a formicarium, can be challenging but is certainly worth the effort for insect enthusiasts!
Introduction to keeping ants
Ants belong to the taxonomic group Hymenoptera, just like wasps and bees. All ant species live in colonies, there are no solitary ant species. Inside a colony of ants the tasks are very stricly divided: the queen lays eggs, the workers take care of the larvae, collect food and build the nest. All worker ants are females. Some species of ants have different worker types, they look different than the other works to be able to perform a specific task better. The worker types are called castes (one caste, two castes) and can be specialized in defending the colony, getting big or small food items to the colony or even storing food in their body. One example of an ant caste is the soldier ant. Soldier ants are usually larger than the other workers and have big mandibles used to bite. They will defend the nest against intruders.
Once a year the colony will produce new queens and kings. These ants are different than the workers because they are able to mate and lay eggs. The new kings and queens will leave the colony to start a new colony somewhere else.
There are around 22.000 different species of ant on Earth. Ants can be found on every continent except antartica and can be called very succesfull creatures in evolution: if you add all the dry biomass of all animals on earth up, 15 to 25% of this biomass is from ants.
Genetics of ants
Ants and other Hymenopetera have a haplo-diploid sexdetermination system. This big word means that the genetics of male and female ants are not determined by X or Y chromosomes as in humans, but are determined by the total number of chromosomes. Male ants have only half the number of chromosomes than female ants. This is because male ants develop from unfertilized eggs. Every chromosome in this haploid egg occurs only once. Female ants develop out of fertilized eggs. Every chromosome in this diploid egg occurs twice, one set came from the mother and one set from the father.
The social system inside a colony of ants is called an eusocial system; ants show eusociality. An eusocial species will have a queen that lays all the eggs and has sterile workers that will work for the colony without reproduction. In eusociality workers will serve the colony without producing their own offspring. This has baffled biologist for a very long time. It is astonishing to see that an animal will sacrifice its life to defend its colony and that an animal will work without reproducing. The system does not seem stable in evolutionary sense. In evolutionary theory genes are spread to the next generation based on the success of the parents: more adapted parents/more successful parents will spread relatively more genes to the next generation than less adapted parents. The next generation will therefore have relatively more of the genes that caused the adaptedness or success than the previous generation. But in ants this system does not seem to work at first sight; workers don’t reproduce and therefore the genes that make them workers do not spread to the next generation. And if there is a sneaky worker that does produce some eggs, these sneaky genes are spread to the next generation and will therefore increase in frequency. At first sight the existence of eusociality is a paradox. But it turns out the system works through a different way. The queen and the workers are sisters, therefore many of the genes present in the queen are also present in the workers. When the workers help to raise their sisters offspring, they will spread their own genes as well. Raising two nephews or nieces will result in spreading the same number of genes as would be spread by raising a son/daughter. Because working in a colony is much more efficient than raising offspring individually when you are an ant, more ant genes can be spread when living in an eusocial system than individually. Other species like termites, bees, wasps and naked mole rats have adopted the same eusocial system. The terms biologist use are ‘inclusive fitness’ and ‘kin selection’ to explain eusociality. Please Google these terms to learn more about it. My explanation is short and incomplete, as there are many subtleties to this explanation.
Looks and species of ants
Everyone can tell you what an ant looks like. Six legs, two antenna, a body made out of three pieces (head, thorax and abdomen). Some ants have wings, these are the kings and queens. Ants can come in many colors including black, brown, yellow and red.
Most common pet ant species are the black garden ant Lasius niger, the harvester ant Messor barbarus and the red ant Myrmica rubra. Lasius niger is a very common and well know ant in Europe and also occurs in the United States. The harvester ant Messor barbarus is an ant species from South-Europe and is a favorite pet ant because of the different worker castes. It has small (minors) and large workers (majors) and can be fed with seeds making it easy to feed these ants.
Pet ant colony housing
Pet ants can be kept in a simple glass test tube until the colony is big enough to be moved to a real formicarium. A formicarium is a real ant enclosure with a nest and an “outdoor” compartment. A glass test tube should be filled with sugar water capped with a big wad of cotton wool, behind this cotton will be the ant queen and her offspring. The test tube can be closed off with another cotton wool plug to prevent the ants from escaping. This type of housing does not look attractive at all, but is very efficient for keeping small colonies with a maximum of 25 workers.
A really nice ant housing is a formicarium where the ants feel good and where the owner can observe the ants inside the nest. Such a formicarium consists of a nest area and an “outside” area. The nest area is made of gypsum or concrete with tunnels in it, covered by a glass slate. The glass is covered by something to keep the nest dark, but can be lifted for the owner to take a peek inside the nest. The “outside area” is the place where you will place the food for the ants and where they will dump their garbage. Both areas are protected against escaping ants by closing it off or by covering the outside edges with teflon.
There are many types of formicaria that all look nice, I’ll show just one. A jelly ant nest as sold by kids toy shops are not suitable to keep an ant colony in, no matter what the package says.
To build this formicarium you will need a square or rectangle tin or plastic box, a clear rubber or plastic tube with a diameter of 1 cm, gypsum powder, play-doh soft clay and a glass slate just a bit smaller than the top of the tin or plastic box. The box should be 20 x 10 cm with a height of 4 – 6 cm for a small colony of ants (up to 150 workers). To make the nest area: use the clay to make a tunnel system on top of the glass slate. It should look like the picture above, including the water ditches and round nest chambers. Make a connection between the clay and the rubber tube. Then fill the tin box with gypsum (water + gypsum powder, as on the package). Suspend the glass slate with the clay-side down into the gypsum and let it become hard. Do not let the glass go under the gypsum, it should stay on top of it. When the gypsum has set you can remove the glass and take the clay off. If you put back the glass slate after cleaning it, you will have a finished nest area! Make sure the rubber tube goes from inside the tunnel system to outside the tin box.
You should weekly fill the water ditches with water. This will move through the gypsum and will make the nest moist in some places. The ants can choose where to live based on the amount of moisture.
Ants can chew or dig through gypsum, given enough time. Always make sure that the tin or plastic box is ant-tight. Ants can pick up their eggs and larvae and just take off completely.
The rubber tube is used to connect the nest area to the “outside” area. The easiest outside area is a plastic box that can be closed off completely. It should have air holes or should be open on top with the edges covered in teflon or paraffin oil (replace regularly!) to prevent the ants from walking out. On the bottom of the outside area you should put white sand. Also place the food for the ants in the outside area. Remove all waste the ants place here weekly.
Food for pet ants
What ants eat depends on the species. In general ants eat dead or live insects and a mix of water and sugar (or water and honey). Some species eat seeds, like the harvester ant Messor barbarus, next to their insects and their sugar-water. Now and then you can feed your ants also fruit, a piece of meat, pollen or syrup.
You can make sugarwater for ants by mixing 7 units of water with 1 unit of sugar (or honey). You can pour this in the lid of a soda bottle and place this in the “outside” area of your formicarium. Replace this water every 2 – 3 days. Never let it run out.
The insects you can feed to your ants are freshly dead or live fruitflies, small crickets, flies, moths and aphids. The proteins in these bugs are very important for the well-being of your pet ant colony
Humidity and temperature for an ant formicarium
The best air humidity for an ant colony depends on the ant species, some need their nest dry while others need it moist. The ants know best what is good for them, so you should offer them different moisture areas inside the nest. The ants will move their offspring to their optimal humidity. Read more about making water ditches to provide the ant colony with moisture at the section about “Pet ant colony housing”.
The temperature for a formicarium should be between 20 and 28 °C, with a drop in temperature by night to maximally 15 °C. You can heat the nest with an electric heat mat or with a lamp. The nest should be kept dark at all times, but if you cover the nest area with black plastic or paper you can heat this with a lamp. Always be careful for fire hazard! And overheating your ant nest is deadly to the ants within a couple of hours.
Developmental time and development of an ant colony
The time is takes for an ant to develop from egg to adult ant depends on the species, the environmental temperature and the caste of the ant. Most ant species take around two weeks to develop from egg to worker. The growth of the colony depends on the number of eggs the queen lays and on the success of the development of these eggs. If you have a colony with bad conditions, like too few proteins in the food, too high or low humidity, too high or low temperature or stressful conditions like bright light inside the nest area, the eggs and larvae die.
An ant colony becomes as old as its queen: around 3 to 10 years depending on the ant species and how well you care for them.
Buying ants or collecting them from nature
You can buy an ant colony or ant queen, or you can collect one from nature. For both options you will have to choose to get only a queen or a queen with already some workers. If you find or buy a queen without workers, you don’t know if she mated. If she never mated, she will never start a colony. If you want to buy an ant queen to start a colony, I would recommend to buy one with eggs or workers so you are sure she mated. If you collect ants from nature, I recommend getting only a queen as they are very easy to find. In summer ant colonies will produce young queens that can be found anywhere. When you find them without wings, they are probably mated. You won’t disturb nature by getting one or two of these young queens.
You can also dig out a complete ant nest to find the queen. I strongly disprove of this. You will destroy a complete ant nest and you might not find the queen. Without the queen you cannot keep ants in a functional nest as a pet. Some ant species are protected by law from disturbing them.
Do not release foreign ant species into nature! This will disturb the natural balance in nature and in some states or countries this even against the law.