Termites are eusocial insects defined by a strict division of labor, with the queen as the sole initial egg-laying female. Unlike most other social insects, a termite colony is founded by a monogamous pair: the primary queen and her mate, the king. The colony’s existence revolves entirely around the queen’s reproductive capacity, as this royal pair is the genetic source for every individual in the established society.
Anatomy and Function of the Primary Queen
The primary queen undergoes a dramatic physical transformation known as physogastry, where her abdomen becomes immensely enlarged and distended. This extreme size results from the vast development of her ovaries and the accumulation of fat deposits necessary to fuel continuous egg production. This massive abdominal expansion means the queen is immobile, permanently confined to a protected chamber called the royal cell.
A mature queen in large species can reach several inches in length and produce thousands of eggs daily. The queen’s longevity is exceptional among insects, with some individuals estimated to live for 10 to 50 years, maintaining near-maximal fertility throughout her life.
The queen and king govern the colony’s social order through chemical signals, or pheromones, which are distributed among colony members via grooming and food sharing. These pheromones suppress the development of other individuals into reproductives, thereby maintaining the colony’s reproductive monopoly.
The primary queen’s partner, the king, remains inside the royal cell with her for their entire lives. Termites differ from ants and bees because the king is required to continually fertilize the queen, as she does not store sperm for life.
The Non-Reproductive Castes
The queen’s immense reproductive output is sustained by the sterile castes, which perform all the labor necessary for the colony’s survival. The largest group is the workers, which are typically small, soft-bodied, and blind. Workers are responsible for a wide range of duties:
- Foraging for food.
- Feeding the queen and king.
- Constructing and repairing the nest.
- Grooming other colony members.
Workers are the primary cause of damage to human structures as they chew and consume wood to feed themselves and others. The other non-reproductive group is the soldiers, whose sole purpose is colony defense. They possess highly specialized heads and powerful mandibles used to combat predators, primarily ants.
In some species, such as the Nasutitermitinae, soldiers have a snout-like head (nasus) and defend the colony by ejecting a sticky, resinous liquid instead of biting. Because their specialized mandibles or snouts make feeding difficult, soldiers rely entirely on the workers to be fed.
Emergency Reproductives and Colony Expansion
A colony must have a contingency plan for reproduction, which involves the development of secondary and tertiary reproductives, often referred to as neotenics. These individuals are developed within an established colony, not as founding females. Neotenics can be triggered to develop if the primary queen dies, a process known as orphaning, which removes the inhibitory pheromones she produces.
They can arise from nymphs or even workers, which then undergo a molt to become functional egg-layers. In some large colonies, neotenics may develop even while the primary queen is alive, serving as supplementary reproductives to decentralize egg production and boost colony growth.
These replacement reproductives are generally smaller, more mobile, and do not achieve the extreme physogastry of the founding queen, but multiple neotenics can collectively match or exceed her egg-laying rate. The process of swarming, where winged reproductives called alates leave the nest to found entirely new colonies, remains the primary method of long-distance colony expansion.