THE 48-YEAR CURSE
The
wild bamboo forests in northwest India and parts of Burma are home to
an odd curse: Every 48 years, like clockwork, they produce an army of
hungry rats that devour the local rice crop. The phenomenon is called mautam
(which translates to “bamboo death”) and is caused by the life cycle of
melocanna bamboo, the local variety. The plants live for exactly 48
years, at which point entire forests die off simultaneously. But before
they die, they produce a tremendous amount of seed-filled fruit. The
fruit will replant the next generation of bamboo, but in the meantime,
it also provides a huge increase in the amount of food available to the
local black rat community.
When that happens, millions of starving rats swarm the countryside, eating everything in their path… which spells disaster for the local rice farmers. In the past, without advance planning and no ability to bring in extra food from outside the region, the rat plague could lead to famine and political upheaval. As for the rats, once they’ve decimated the rice crop, they starve to death en masse. Their population numbers crash back down, but everyone knows they’ll be back… in 48 years.
THE HOUSE MOUSE INVASION
The mice that cause such destruction Down Under actually belong to one of the most common mouse species in the world: the house mouse. Native to Asia, these mice abandoned foraging in the wild in favor of scavenging in human settlements nearly 10,000 years ago. And as human agriculture and civilization spread across the globe, the house mice spread too. They most likely arrived in Australia as stowaways aboard the first ships that brought settlers there in the 1780s.
House mice are among the fastest breeders in the world. A female’s pregnancy lasts just 19 days and produces five to ten baby mice. Those baby mice start having their own babies when they’re only six weeks old. Oh, yeah— and females can get pregnant again just one to three days after giving birth. This means that one female mouse can produce 500 new mice in less than six months.
THE ORIGINAL AND STILL THE WORST
It turns out that locusts are just regular grasshoppers driven crazy by overcrowding. The desert is a harsh environment, and there’s usually not enough food to support a large grasshopper population. To ensure survival of the species, female grasshoppers lay as many as 150 eggs just under the surface of loose, sandy ground. Ordinarily, not all of the eggs hatch— and not all of the ones that hatch survive. But when a particularly wet winter comes along, two things happen: First, more of the eggs hatch. And second, the extra moisture means that extra vegetation grows, providing enough food to support the extra population… at first.
Scientists aren’t exactly sure why, but overcrowded conditions cause grasshoppers to change both their appearance and their behavior. Their color morphs from green to a yellow-and-black pattern. More importantly, their personalities change— from solitary individuals to being clustered together in an organized mob that moves across the landscape as one giant, food-frenzied unit. Weird but true.
Bonus: The
swarm, American-style. For the first three or four decades of
settlement on the Great Plains, American farmers regularly had their
crops wiped out by the Rocky Mountain locust. In 1874, a swarm of
locusts estimated at a size of 198,000 square miles— about twice the
size of Colorado— swept through Nebraska. By the early 1900s, the Rocky
Mountain locust had disappeared from the landscape, apparently gone
extinct. The only explanation scientists have come up with for why this
happened is that the settlers may have plowed up the locusts’ breeding
grounds without even realizing it.
