Termites are, genetically speaking, a branch of the cockroach family tree
Termites once had an insect order all to themselves. DNA changed that: they evolved from inside the cockroach lineage, so biologists now file both in one order, Blattodea. Their closest living cockroach cousin, the wood-eating Cryptocercus, even shares termite gut bacteria and grooms its family like a tiny colony.
Blattodea holds roughly 4,400 cockroach species in almost 500 genera and around 3,000 termite species in about 300 genera. Together with the mantises, it forms the superorder Dictyoptera. A study comparing five DNA sequences across 107 species found termites nested within the cockroaches, with the family Cryptocercidae as their sister group, and mantises as the sister group of the whole order.
On the surface the two look like opposites. Termites are pale and soft-bodied, living in colonies where a king and queen produce every member and sterile workers and soldiers do the rest. Cockroaches are usually brown and armoured with hardened plates, and while they often gather in groups, every adult can breed. Yet they share a long list of habits likely inherited from a common ancestor: a liking for warm, damp places, burrowing, food sharing, trail following, recognising kin and communicating by vibration. The overlap is strongest with juvenile cockroaches, which huddle together, while adults tend to fight over space.
Company matters to both. A termite kept alone loses vigour and dies sooner than a pair, and an isolated cockroach nymph can grow at less than half the rate of grouped ones. Young cockroaches, poor foragers, eat the droppings of larger individuals and pick up the gut microbes that help them digest. Termite workers feed the royals and young mouth to mouth or from the other end, supplying all their nutrition that way.
Cockroach-like insects dominated the Carboniferous, and modern groups had radiated by the middle of the Mesozoic. Today cockroaches live on every continent, in leaf litter, caves and even water; only a few have become household pests. Termites reach every continent except Antarctica, with the greatest variety in Africa, where mounds can stand nine metres tall and thirty metres across, creating patches of richer soil and local hotspots of biodiversity.
Source: Blattodea
