Termites, social insects which live in colonies that, in some species, contain 2 million individuals or more, are often incorrectly referred to as white ants. But they are certainly not ants. Termites, unlike ants, have gradual metarnorphosis with only three life stage: egg, nymph, and adult. Ants and the other social members of their order, certain bees and wasps, have complete metarnorphosis in four life stages; egg, larva, pupa, and adult. The worker and soldier castes of social ants, bees, and wasps consist of only females, all daughters of a single queen that mated soon after she matured and thereafter never mated again. The worker and soldier castes of termites consist of both males and females, and the queen lives permanently with a male consort.

Since termites are small and soft-bodied, they easily become desiccated and must live in moist places with a high relative humidity. They do best when the relative humidity in their nest is above 96 percent and the temperature is fairly high, an optimum of about 79°F for temperate zone species and about 86°F for tropical species. Subterranean termites, the destructive species that occurs commonly throughout the eastern United States, attain these conditions by nesting in moist soil that is in contact with wood, their only food. The surrounding soil keeps the nest moist and tends to keep the temperature at a more or less favorable level. When it is cold in winter, subterranean termites move to burrows below the frost line.

Some tropical termites are more ingenious engineers, constructing huge above-ground nests with built-in “air conditioning” that keeps the nest moist, at a constant temperature, and well supplied with oxygen. Among the most architecturally advanced of these termites is an African species, Macroternes natalensis. Renowned Swiss entomologist Martin Luscher described the mounds of this fungus-growing species as being as much as 16 feet tall, 16 feet in diameter at their base, and with a cement-like wall of soil mixed with termite saliva that is from 16 to 23 inches thick. The thick and dense wall of the mound insulates the interior microclimate from the variations in humidity and temperature of the outside atmosphere. Several narrow and relatively thin-walled ridges on the outside of the mound extend from near its base almost to its top.

According to luscher, a medium-sized nest of Macrotermes has a population of about 2 million individuals. The metabolism of so many termites and of the fungus that they grow in their gardens as food helps keep the interior of the nest warm and supplies some moisture to the air in the nest. The termites saturate the atmosphere of the nest, bringing it to about 100 percent relative humidity, by carrying water up from the soil.

But how is this well-insulated nest ventilated? Its many occupants require over 250 quarts of oxygen (more than 1,200 quarts of air) per day. How can so much oxygen diffuse through the thick walls of the mound? Even the pores in the wall are filled with water, which almost stops the diffusion of gases. The answer lies in the construction of the nest. The interior consists of a large central core in which the fungus is grown, below it is “cellar” of empty space, above it is an “attic” of empty space, and within the ridges on the outer wall of the nest, there are many small tunnels that connect the cellar and the attic. The warm air in the fungus gardens rises through the nest up to the attic. From the attic, the air passes into the tunnels in the ridges and flows back down to the cellar. Gases, mainly oxygen coming in and carbon dioxide going out, easily diffuse into or out of the ridges, since their walls are thin and their surface area is large because they protrude far out from the wall of the mound. Thus air that flows down into the cellar through the ridges is relatively rich in oxygen, and has lost much of its carbon dioxide. It supplies the nest’s inhabitants with fresh oxygen as it rises through the fungus-growing area back up to the attic.

白蚁是生活在蚁穴中的群居昆虫，有些白蚁的蚁穴可以容纳两百万或者更多的白蚁。白蚁通常被错误地称为白色蚂蚁，但它们肯定不是蚂蚁。跟蚂蚁不同的是白蚁的渐变形态只有三个阶段：卵，若虫，和成虫。而蚂蚁和同目的其他动物，如某些蜜蜂和黄蜂，属于全变态昆虫，形变过程需要四个阶段；卵，幼虫，若虫和成虫。蜜蜂和黄蜂的工蜂以及蚂蚁的工蚁只有雌性，这些雌性都是一个蜂后或蚁后所生，蜂后或蚁后成熟后不久就交配，一生就只交配一次。但是白蚁中的工蚁有雌性也有雄性，且蚁后会长期与一个固定的雄性配偶一起生活。

由于白蚁是小而软体的动物，很容易干燥脱水，所以必须生活在相对较潮湿的地方。对白蚁来说最适合生存的蚁穴相对湿度在96%以上，温度也要比较高，温带最适合白蚁的温度是79°F，热带约为86°F。地下白蚁作为破坏性的物种，通常出现在美国东部，它们在有木头（唯一的食物）的潮湿土壤中筑巢，那里可以达到这些温湿条件。周围的土壤可以保持巢的潮湿，并使得温度保持在一个差不多的有利水平。在冬天寒冷的时候，地下白蚁会搬到霜冻线以下的洞穴里。

一些热带白蚁是更聪明的工程师，它们可以建造有巨大的内置“空调”的地上巢穴，保持巢穴潮湿，温度恒定，氧气充足。这类白蚁中在建筑上最先进的是一种非洲白蚁叫Macroternes natalensis。著名的瑞士昆虫学家马丁•吕舍尔将这些以真菌为食的白蚁建造的土丘描述为：高16英尺，底部直径16英尺，白蚁用自己的唾液和泥土混合成一种类似水泥的材料，建起16到23英寸厚的土壁。厚密的墙壁把内部小气候与外界的温度和湿度变化隔绝开来。巢穴外部几个狭窄且相对薄的隆起从底部附近几乎延伸到它的顶部。

据吕舍尔说，这种非洲白蚁的一个中型巢穴约住着200万只白蚁。这么多的白蚁和生长在花园中的食物真菌的新陈代谢有助于维持巢内的温度和巢内空气湿度。白蚁们使巢穴内的空气湿度饱和，通过土壤中的水达到约百分之百的相对湿度。

但是，这种隔绝的巢是怎么通风的呢？巢内生存的白蚁每天需要超过250夸脱的氧（超过1200夸脱空气）。这么多的氧气怎么扩散到厚厚的墙壁里去呢？就连墙壁上的小孔里都充满了水，这使得空气几乎无法扩散。问题的答案在于巢穴的建造结构。其内部有一个很大的核心区域，那里生长着大量真菌，其底下是空的“地下室”，上面是一个空的“阁楼”，在巢的外墙上的隆起处有许多小隧道，连接“地下室”和“阁楼”。在真菌花园的暖空气会上升到阁楼。从阁楼上，空气穿过隆起处的小隧道，然后流向地下室。气体，主要是进来的氧气和出去的二氧化碳，就很容易扩散到或离开隆起处，因为这些隆起从巢穴墙壁往外延伸很多，所以它们的壁薄、表面积大。因此，通过隆起进入地下室的空气氧气含量相对高一些，而且二氧化碳已经减少了。气流从真菌生长区上升到阁楼上，白蚁们就呼吸到了新鲜的空气。