“Endlessly Fascinating But Rarely Observed”: Inside the Hidden World of Cockroaches

Few people have a good word to say about roaches but, like every insect on the planet, look close enough and you’ll find something to admire. Besides, it’s not just those unloved species, barely glimpsed as they scurry into cracks and crevices when you turn on the light in the kitchen. There are well over 4000 species around the world, of which just 30 are considered pests. But even one of the most ubiquitous pests, the American cockroach, is still worth a second look—it’s a masterpiece of engineering. At the rear of its abdomen are two structures that look like antennae stuck on the wrong end of the insect. They’re called cerci and they can detect even the slightest air movement—perhaps a predator trying to stalk it. Because the roach has two of these it can even sense exactly where the disturbance is coming from and head in the opposite direction. They’re so sensitive, scientists have been trying to copy them, to equip robots with the same abilities.

It’s really hard to sneak up on a roach and once alerted, it doesn’t hang around. Roaches are among the fastest things on six legs and can cover four feet in a second. At high speed, all six legs leave the ground at once, like a galloping horse. But when they hit warp speed, they do something no horse could ever do—they lift onto their back legs and run bipedally. And they can squeeze into the narrowest crack. Although they’re encased in a tough outer skeleton, it’s so flexible that a roach can squash down to just a quarter of its height—which probably also explains why they’re so hard to squish by stomping on them.  It’s not surprising that you only ever catch a glimpse of them—which is a pity, because some of them have a more endearing side.

Many kinds of roaches are doting moms and carry their young with them wherever they go. Sometimes they’re slung under mom’s abdomen but one kind, called Thorax porcellana, which looks more like a beetle than a roach, has hard, domed wing cases. Beneath these is a cozy space for her 30 or 40 youngsters, safe from predators and from the elements. This roach, like many others, also feeds its babies on secretions that ooze through gaps in its tough body case. The Pacific beetle roach, though, has gone even further. It produces cockroach milk—and it’s pretty wholesome stuff. It contains three times the calories of most mammal milk. So, baby beetle roaches get off to a good start in life.

That’s also true for the young of the world’s biggest roach—the giant burrowing roach. You’ll need to visit the dry gumwoods of Queensland’s outback to find this magnificent beast and even then, it’s not easy. They dig deep, corkscrew-shaped burrows in the hard-packed soil, which reach down a yard or more. At the bottom is a nest chamber, a secure home for mom and her family. The babies’ diet isn’t as rich as their beetle roach cousins—their mother only brings them dried bits of gum leaves to eat. But at least she chews them up and her babies jostle around her to feast on the fragments. I’m reminded of piglets around a sow—a thoroughly heartwarming sight. Despite their meager diet, the babies stay with their mother for most of the summer, until they’re big enough to face the tough world of the outback on their own. Sometimes, though, the kids never leave home.

In the Appalachian forests of North Carolina and Tennessee there are roaches that live in little societies. You might think that all roaches are social, after all you sometimes find hundreds packed into tiny spaces. But in these groups, it’s every roach for itself. Eastern wood roaches on the other hand live in permanent societies made up of an extended family. Their home is a series of galleries chewed through rotten logs and here both parents live with 30 or 40 offspring, all of which help construct the network of tunnels.

Roach life is endlessly fascinating but rarely observed. For this reason, I keep colonies of several species from around the world—headlight roaches from Central America, tiger roaches from Madagascar, question mark roaches from India and emerald roaches from southeast Asia among lots of others. Many are as beautiful as any butterfly or beetle. Question mark roaches for example are jet black with white splotches on their backs, including one in the shape of the eponymous question mark. Emerald roaches are a stunning iridescent green. In addition, I’ve built cutaway sections of burrows to observe the complex family lives of burrowing roaches and wood roaches, and the more I watch them, the more endearing these creatures become. However, I’m not alone in my appreciation of these unloved insects. Around the world, there’s a network of people who breed and rear cockroaches of many species and exchange information and animals—and of course passion. But if you’re still not convinced then let me reveal the biggest roach legacy to our planet.

Remember those social Appalachian roaches? They look and behave suspiciously like termites and now that we can plot the insect family tree using DNA, we know that termites and cockroaches are one and the same. Termites are just highly social roaches. Although, like roaches, some are pests, others shape whole ecosystems across the planet. They build magnificent castles of clay that tower many yards above the ground and have such efficient air conditioning that architects have adapted termite designs for their own buildings. One giant mound stands next to a dirt track—grandly called the Plenty Highway—across Australia’s outback. Imagine a termite scaled up to human height—then what they’ve built here is the equivalent of four of Dubai’s Burj Khalifa (the world’s tallest building) stacked on top of each other. That’s a fitting monument to the humble roach.

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Excerpted from Alien Worlds: How Insects Conquered the Earth, and Why Their Fate Will Determine Our Future by Steve Nicholls. Copyright © 2023. Available from Princeton University Press.