The Mormon cricket is one of North America's more fascinating - and more gross - insects. It grows up to three inches long, approximately the size of an iPod Nano made of insect, native to Utah and the Desert Southwest. Most of the time, the Mormon cricket is a solitary creature, not venturing far from home. But every once in a while, for reasons unknown, it transforms into a swarming menace.
The Mormon cricket (actually a katydid) is typically a dark brown color, which provides it with protective camouflage. But when it begins to gather, it undergoes a transformation into a brightly colored insect. This transformation happens along with behavioral changes, from a solitary animal to a flocking one that seeks out (or is driven to) large numbers of its own kind.
And then somehow a switch gets flipped, and this large collection of (now brightly colored) insects starts marching across the land, eating everything in its path.
The Mormon cricket gets its name from a legend of the Mormon church. When the earliest settlers arrived in Utah and planted their crops, they were quickly destroyed by a horde of the crickets. But the settlers were saved by a secondary wave of California gulls which followed the Mormon cricket boom and gobbled them up. In the Mormon faith, this is known as the Miracle of the Gulls.
Flocking behavior helps to drive the horde forward, just as it does with birds and fish. But another prod to keep it moving forward is that when they swarm, Mormon crickets become cannibals. Imagine being part of a big crowd at a fair or a festival. Now imagine how much faster you would move if the people behind you started nipping at your arms and shoulders whenever you paused for a moment! Every Mormon cricket is constantly being driven forward by the bites of the crickets behind it.
This cannibalistic behavior also greatly contributes to the befouling of roads. When the swarm encounters a road, it quickly gets smashed into gooey oblivion by passing traffic. But other Mormon crickets stop to dine on their fallen counterparts, and they get squashed, too. In much the same way that Dire wolves and Sabertooth cats got trapped in the La Brea tarpits when they were lured in by the "easy" prey trapped in the tar, the Mormon crickets become a moving buffet of vehicular slaughter.
In fact, aside from destroying crops, Mormon crickets pose a serious threat to motorists. A road slick with insect guts is a dangerous road for driving. Drivers are often taken by surprise by the sudden appearance of a horde, which certainly contributes to the risks.
Mormon crickets are unusual in one final respect: unlike most insects, the male Mormon cricket "makes a substantial contribution to the growth and survival of his offspring." When Mormon crickets mate, the male gives the female a big blob which is mostly food attached to a small packet of sperm. The female eats the food packet as the sperm drains into her body. The blob is up to 27% of the male's body weight, which is a significant loss for the male - and a significant boon for the female. (Just for perspective, that's the equivalent of a 150lb man giving his sweetheart a 40lb chunk of his flesh.)
Photo credit: Flickr/NiferCritter