UNBEKNOWNST TO THE average urban surface-dweller, termite colonies in many southern Ontario communities form vast subterranean cities, sometimes with millions of inhabitants and stretching for hundreds of metres (or yards) across residential blocks. Tiny, white, eyeless insects throng through interlacing tunnels leading to widespread dormitories, nurseries, royal chambers and innumerable eateries in dead, damp wood. Rotting roots, stumps, fence posts, picnic tables, decks, indoor beams and floor joists are prime termite fare. To turn wood into a meal — something almost no other animals can do — the little lumber chompers tote gutfuls of microscopic protozoans. The symbiotic one-celled creatures break cellulose down into digestible carbohydrates and account for about one-third of a termite’s total weight.

Though eastern subterranean termites may have been long established on the shore of Lake Erie near Windsor, others arrived in Ontario as Depression-era migrants, probably in crates or pallets from the eastern half of the United States. They first turned up in a Toronto waterfront warehouse in 1938 and spread through the city’s east end over the next 20 years. Today, they reach into Brampton, Richmond Hill and Pickering, while most of Ontario’s other infestations centre around the Kitchener-Guelph and Windsor areas.

Though seemingly antlike, termites are of far greater antiquity and more closely related to cockroaches. With softer, thinner skin than ants they shun the open air and light to keep from fatally drying out. Within the dark, dank chambers and tunnels of termitaries, the walls of which are plastered with hardened termite dung, the humidity is above 90 percent, while carbon-dioxide levels from wood-processing flatulence are up to 100 times higher than in the open air. To venture above ground, termites build grey, snaking tubes, up to 2.5 centimetres (one inch) wide, of saliva-moistened dirt cemented with droppings, leading to cracks in the foundations of houses or up tree trunks to dead branches.

Unlike ant societies, termites also have gender equality, with castes of workers and soldiers made up of both sexes, and a resident founding “king,” as well as a “queen.” Workers take care of the building and upkeep of the colony, tend the eggs, young, soldiers and royal breeders and feed them regurgitated sawdust from wood-chewing forays. Soldiers (larger of the three illustrated) — which have armour-plated heads twice the size of those of workers and long, fearsome mandibles — comprise 1 to 2 percent of the population. They guard against ant attacks and, like bouncers, bar entrance to all lacking a distinctive scent spread among colony members from pheromone secretions by the queen.

Reproductive adult termites are black, equipped with long wings and functioning eyes. They fly in swarms on warm, sunny mornings in late winter or spring, most often around early May. After usually less than 10 minutes in the air, they land, snap off their wings and seek out the opposite sex. The very few that pair and survive crawl into an unoccupied crevice, dig out a honeymoon suite and start a new colony as the king and queen. But isolated small new colonies of termites usually can’t survive northern winters. Ontario populations rely much more on select wingless breeders that are light-orangish or mottled and establish adjunct egg-laying chambers, like suburbs, near the edges of their home colonies. Most long-distance dispersal occurs through termite-infested soil, building materials or firewood being transported by humans.