By Henry Nicholls
Reputation: Yuck. Cockroaches are filthy, immortal scavengers that are unaffected by radiation. In a post-apocalyptic world, it will be these dirty little critters that survive. We would be better off without them.
Reality: There are almost 5,000 species of cockroaches, of which only around 30 have any pest-like tendencies. These few malign a group of insects that boasts an astonishing, enriching diversity of forms. Cockroaches are pretty well toasted by radiation.
The sight of a cockroach scuttling across the kitchen floor is distinctly unsavoury. This emotional truth has led most of us to believe that all cockroaches must be similarly repugnant.
But not George Beccaloni, curator of orthopteroid insects at the Natural History Museum in London, UK. He is on the side of the cockroaches. “People have a very biased view of the group,” he says.
Cockroaches are found on all continents apart from Antarctica, from rainforests to deserts
Less than 1% of the 4,800 known species of cockroach cause humans any bother, yet few of us give the 99% a second thought. This is manifestly unfair, says Beccaloni.
He points out that there are about as many cockroach species as there are mammals. So writing off all cockroaches, based on our dislike of 30 or so species, “is like encountering a mouse or a rat and then branding all mammals as disgusting vermin,” he says.
I take the point, but remain unconvinced. Mammals are spectacularly diverse. I think back to a childhood holiday in Sardinia, where our flat was plagued by cockroaches. How different can the rest of cockroaches be? Beccaloni takes the next half hour to enlighten me.
For a start, they live in a huge range of habitats.
“Cockroaches are found on all continents apart from Antarctica, from rainforests to deserts,” says Beccaloni.
The appealingly-named Megaloblatta blaberoides boasts a whopping wingspan of over 7in (18cm)
The abundance of species is greatest in the tropics, and at low altitudes where temperatures are high. However, there are those can cope with extremes. Eupolyphaga everestiana is a montane specialist that lives on Mount Everest at well over 16,400ft (5,000m) above sea level.
Since they live in so many diverse environments, it is not surprising that cockroaches should come in many different shapes and sizes.
The smallest species on record is the ant cockroach, which lives in the nests of leaf-cutter ants in North America. At just a few millimetres long, it is dwarfed by its hosts.
In contrast, the appealingly-named Megaloblatta blaberoidesboasts a whopping wingspan of over 7in (18cm).