The 17 year Cicada are emerging in the midwest, and reports are that the hatch is spectacular. Wikipedia cites the following about these insect versions of Haley's comet:
"Magicicada is the genus of the 13-year and 17-year periodical cicadas of eastern North America. Although they are sometimes called "locusts", this is a misnomer, as cicadas belong to the taxonomic order Hemiptera (true bugs), suborder Auchenorrhyncha, while locusts are grasshoppers belonging to the order Orthoptera."
While other specie of Cicada have shorter 2 to 3 year, or even annual emergence cycles, the Periodic Cicadas are notable for the sheer numbers of insects that crawl out of the ground after such an extended maturation period. Swamping the environment with so many organisms ensures that some survive the wide array of animals, birds and fish that feast on the insects, a biological strategy known as predator satiation.
51 years -- and three hatch cycles ago -- I remember playing with shed Cicada husks as a kid in Ohio. Amazingly durable, the emergent casings were complete representations of the outer profiles of gigantic bugs that looked like alien invaders. I would collect them, then pit them in epic battles against my squadrons of green plastic army men, who routinely fell under the onslaught of creatures that, to scale, were the size of Volkswagens.
The current emergence, known to scientists as Brood V (last seen in 1999), is considered a medium sized Periodic Cicada event. As reported recently by Slate.com, "We know how cicadas detect seasons: They get important clues about where trees are in the growth cycle from the composition of the roots they feed on. But no one knows for sure how they keep track of how many years have passed. It's likely that the gene or genes responsible are the same ones involved in timing in other organisms — such as the ones that tell birds how and when to fly south for the winter and salmon how to swim to their ancestral breeding pond. "We know it's some sort of molecular clock," says Chris Simon, an ecologist and evolutionary biologist at the University of Connecticut. "But researchers will have to study those kinds of timing genes in depth before they unravel this mystery."
The following excellent time lapse video of 17 year Cicada emergence on Vimeo illustrates the life cycle of these amazing organisms.
Well known midwest guide and fly fisher Blane Chocklett has his own strategy for dealing with these kinds of events -- his imitation Cicada pattern is probably the most accurate representation of the insects I've ever seen. Almost qualifying as etymological taxidermy, this pattern is proven to catch every fish that eats Cicadas -- which is pretty much all of them.