Yes, ants do molt. Molting is an important process in the ant’s life cycle. It is through molting that they undergo metamorphosis and grow from larvae to adult ants. In fact, ants molt multiple times before they mature.
In this article, we’ll learn more about ants and molting as we discuss the following:
- Definition of molting
- When do ants molt?
- Why do ants molt?
- How do ants molt?
What Is Molting?
Molting is the biological process in which an animal sheds or replaces a part of its body. It typically involves an outer layer or covering and other parts like hair, horns, and skin. It occurs regularly or at certain points in an animal’s life cycle.
For ants and other arthropods, molting is technically called ecdysis. It involves the shedding of their hard outer shell, the exoskeleton. 
When Do Ants Molt?
Ants exclusively molt during the larval stage of their development. During this stage, ants take the form of worm-like creatures called larvae.
These larvae look nothing like adult ants. They have no eyes, or limbs, and can only really do one thing, eat. They rely on workers for a constant supply of food which they gobble up to grow rapidly. As they grow, they molt several times to accommodate changes in size.
Why Do Ants Molt?
Ants molt or undergo ecdysis to grow. Unlike us humans, ants don’t have soft flexible skin. Instead, they have hard rigid exoskeletons.
These exoskeletons don’t stretch and therefore, become barriers to development. As ant larvae grow, they have to molt and shed their exoskeletons. Otherwise, they’d get crushed and fail to develop.
Essentially, molting permits metamorphosis. It is through it that the larvae develop into pupae and eventually adult ants.
How Do Ants Molt?
Molting begins when an ant larva grows to a certain size. When it does, stretch receptors in the body trigger the release of the hormone ecdysone. This ecdysone initiates apolysis or the separation of the old cuticle from the underlying epidermal cells.
After separation, the epidermal cells secrete molting fluid. This molting fluid takes up space between the old cuticle and the epidermis. Its purpose is to digest the lower regions of the old cuticle. However, it stays inactive until the upper part of the new cuticle has been formed.
While secreting molting fluid, the epidermal cells also secrete the cuticulin layer. This cuticulin layer eventually becomes part of the new exoskeleton’s epicuticle.
Physiology of ecdysis
Halvard : from Norway., Public domain, via Wikimedia Commons
Once this layer is fully formed, the molting fluid activates and breaks down the old cuticle. Doing so recycles amino acids and chitin that become the inner layer of the new exoskeleton.
As the old cuticle is being digested, the new procuticle is laid down and formed. Once this is done, the new exoskeleton is ready.
At this point, the larva starts shedding the old exoskeleton. It splits the old exoskeleton by contracting its muscles and taking in air to cause its body to swell. Once split, the larva extricates itself and emerges with a new exoskeleton and physical features. 
Larval Instars In Ants
Instars are developmental stages between each molt. These instars are characterized by physical changes manifest in the larval body. In ants, these physical changes may include the following:
- Altered body proportions
- Hair growth
- Head width and structure
For example, Messor aciculatus have 3 instars. These instars have the following distinguishing characteristics:
- Instar 1: Cranium width: 0.24-0.30mm; Very minute hairs on the head prothorax; mandibles with one acute medial toot; No recognizable spinules on the basal half of medial surface.
- Instar 2: Cranium width: 0.29-0.33mm; Short and sparse hairs on head and body; Mandibles with several spinules in addition to one medial tooth; Maxillary palp a rather wide frustum and galea a slender frustum.
- Instar 3: Cranium width: 0.33-0.37mm; Body hairs abundant on the whole surface, Antenna with three sensilla; Mandibles small; One acute medial tooth; Basal half of medial surface with several long spinules; Maxillae lobose; Palps paxilliform; Galea digitiform.
In short, instars of M. aciculatus differ in cranium width, mandibles, and body hair.
Myrmelachista catharinae ants have very similar instars. They have an estimated number of 3 instars. These instars differed in terms of the head capsule, mandibles, and body.
Do Ants Go Through Complete Metamorphosis?
Yes, ants go through complete metamorphosis. Their immature forms look very different from their adult forms. Their life cycle includes 4 stages: the egg, larva, pupa, and adult.
How Long Do Ants Live?
Ants can live for weeks or decades depending on the species and their status in the colony. Ants with episodic roles tend to live the shortest. Males for example only live for weeks and die shortly after they mate.
Workers, on the other hand, live longer as they fulfill an important role in colony growth. That said, they don’t outlast queens which in some species may live up to decades.
Check this article to learn more about ant colony structure.
To summarize, yes ants molt. They molt multiple times during the larval stage of their development. They do so to continue growing as they go through the process of metamorphosis. If they fail to molt, they end up getting crushed by their exoskeletons and fail to develop into adults.