If you are completely new to the world of ants, then this article will introduce you to the basics of ant biology. Everything you need to know about ant biology before you start keeping ants will be described. There is a lot of literature available about ants and therefore this article will only describe ant biology in short. It does not nearly comprise everything about ants, but provides an overall summary, getting you prepared to ant keeping. If you want to know more about ants, there are some really good books available about ants. You might want to check out the books of the myrmecologists Wilson and Hölldobler.
Ants (scientific name: Formicidae) are a family of eusocial (‘real social’) insects, forming colonies varying in size from a few dozen to a few million individuals per colony. The social character of ants is what makes them so succesful as a family. A colony consists of one or several queens (gynes) and workers, who are all the offspring of the queen(s). There are more than 12,000 species of ants known. All species differ tremendously in size, color and behavior, providing an endless source of joy for the ant keeper. Ants have evolved from wasps and belong to the same order as wasps and bees, the Hymenoptera.
Taxonomy is the practice of identifying, classifying and naming organisms. All organisms are divided in several layers of groups. For example, ants belong to the family of Formicidae and to the order of Hymenoptera. Wasps and bees belong to the same order as ants, but not to the same family. Every group is called a taxon. A simple taxonomy of ants is:
There are more layers of taxons, like suborder or superfamily, bet let’s keep it simple. Now we know how to classify ants. But there are more than 12,000 species of ants known. So how do we classify each single species? We group them into genera (singular: ‘genus)’. And within genera, there are species. If we want to name a species scientifically, we use the binomial nomenclature. This means that both the genus and the species will be written. The genus should be capitalized, but the species should not. Both should be cursive. So, for example, we have the species Lasius niger. Lasius niger is a species belonging to the genus Lasius, like Lasius flavus and Lasius emarginatus. But the species Formica fusca is from another genus.
Like all insects, ants have six legs and their body consists of a head, thorax (alitrunk) and abdomen (gaster). Ants have a node between the alitrunk and gaster, called the petiole. As invertebrate animals, they have an exoskeleton. The head contains compound eyes, antennae, and mandibles. The antennae are very important for communication through chemicals (pheromones). Ants have several glands all over their bodies which they use to produce pheromones. Females and males have developed wings on their alitrunk, which they use to fly and mate in the sky (more about that later). In the illustration below you can see an elaborate description of ant morphology.
Ants do not reproduce individually, but rather as a colony: the colony is the reproducing unit. The workers never have offspring, but by helping their mother, the queen, they are able to spread their genes. However, the colony must produce winged females and males (alates) in order to have reproduced succesfully. A colony that dies off before it has been able to produce alates, has failed to reproduce, even if it has produced workers.
So, how does ant reproduction work? There are several ways for the queens to disperse, but I will only describe independent colony founding. A colony produces winged females and males, the alates. Somewhere in spring or summer, depending on the species, when the weather conditions are optimal, the alates will fly out in large numbers. These are called the nuptial flights. They will mate with females and males from other colonies and once fertilized, the female will land, shed off their wings en look for a good place to excavate a nest. The male dies.
The female or gyne is now to become a queen of her colony. She starts laying eggs. The eggs become larvae, and as they are nourished by the queen, they grow large until they become pupae. Pupae of some species will spin a cocoon and some will not. The pupa will develop into an adult worker. The queen entirely relies on her food reserves, hence the large, swollen gaster. This is called a physogastric gaster. The first generation adult workers are slightly smaller than the next generations and they are called nanitics. The life cycle of the ant is represented in the illustration below. It is important for an ant keeper to understand this cycle. In order to start a colony, the ant keeper must capture a freshly mated queen. You can read more about that in my article about how to start an ant colony.
You may have noticed that the workers, females and males all look different. If you want to capture a queen, you must be able to recognize her. A queen can be easily spotted because she is usually considerably larger than the workers. But in some species, the queen is of almost the same size as the workers. It is therefore important to know how to recognize a queen without just looking at her size. This can be done by looking at the alitrunk (thorax), which is oversized compared to the alitrunk of a worker. Compare the thorax to the head of the ant: a queen’s thorax is bigger compared to the head than a worker’s thorax.
Ants show some very interesting behavior. I will write many posts on the behavior of ants, so this section is going to be brief. The most outstanding behavioral characteristics of ants are due to their social character. Ants build nests and the way they do this varies greatly between species. Some ants nest in an acorn, some excavate giant subterranean cities, some build their nest in a tree by folding together leaves, and some nest in hollow trees. The possibilities are limitless and ants exploit them all.
Another outstanding characteristic is the way ants communicate. They make use of pheromones to communicate or to leave a trail leading to a food source. It is a very efficient system, but the code is also easily cracked by other species to parasitize on the host colony.
Some species contain only one queen per colony (monogyny) and some species contain several queens per colony (polygyny). It is important for the ant keeper to know what species are monogynic and what species are polygynic, so he can take that into account when starting a colony.
Other ant behavior is too widespread to discuss in this article, so if you want to know more about this subject, I would suggest to check out this blog’s archives about ant behavior.
The ant keeper must be aware of some basic terminology that will be useful in the hobby. Below is a collection of ant terminology.
- Formicidae: the taxonomic family to which ants belong
- Hymenoptera: the taxonomic order to which ants, wasps and bees belong
- Eusocial: meaning ‘real social’, describing the organized, social and co-operative nature of ants
- Gyne: the reproducing female or the queen of a colony
- Thorax: or alitrunk, the mid-section of an insect’s body, between the head and the abdomen
- Abdomen: or gaster, the posterior section of an insect’s body
- Petiole: the node between the thorax and the abdomen
- Exoskeleton: the hard external skeleton of ants and other insects
- Pheromone: an excreted chemical factor triggering a social response in ants
- Alate: the reproducing individuals within ants, the females and males
- Nuptial flight: the swarming of ants in order to reproduce
- Egg, larva, pupa and adult: the different stages in the life cycle of an ant
- Physogastry: the phenomenon of a visible swollen gaster of an ant
- Nanitic: the first generation of workers that are slightly smaller than the next generations
- Monogyny: the phenomenon of species with colonies containing only one queen
- Polygyny: the phenomenon of species with colonies containing several queens
Now you know some basic ant biology. If you would like to know more, I would recommend the book ‘Journey to the Ants’ by Wilson and Hölldobler. It is a good book to start with. There are more complete books available out there (like the Pulitzer Price-winning ‘The Ants’ from the same writers), but remember that those are aimed at academics.