Cicadas are often mistaken for locusts, but they're actually they are related to leafhoppers or aphids. (Watch a video of actual locusts here.) Locusts are grasshoppers that often travel in vast swarms. Because periodical cicadas appear in such large numbers, early European settlers in North America connected cicadas to the plague of locusts mentioned in the Bible. Cicadas are not locusts.
There are some great articles to help you learn how cicadas work. Basically, they work on a 17 or 13 year life cycle. They won't hurt you. Cicadas do not sting or bite, and their diet consists of the sap from plants. The very loud sound you will hear (mostly during the heat of the day) is actually the mating call of the male cicadas. The sound is not produced by vocal chords, but rather by the buckling of the ribs, the vibration of a membrane and amplification in the cavities of the cicada's abdomen. (You can visit the University of Michigan zoology site to find audio files from various types of cicadas.)
After they sing, the cicadas mate. Afterwards, adult female cicada lay eggs by piercing plant stems and inserting the eggs into the slit created in the stem. The eggs eventually hatch into small, wingless cicadas known as nymphs. The nymphs eventually fall to the ground and dig below the surface. Here they stay for 17 years, slowly growing into adults. The nymphs live on the sap from plant roots while they grow. When the nymphs reach full size, they dig their way to the surface with specially adapted front legs that act as tiny shovels. The nymphs then climb to higher ground and shed their skin for the last time. (see YouTube video) Now they are fully-winged adult cicadas. - How Stuff Works
The last brood to emerge was Brood X (brood #10), which came up in the spring of 2004 in the eastern US. The group of cicadas that will be seen in Chicago this May are named Brood XIII (or brood #13). The last time they surfaced (if you do a little mental math) was in 1990, when I was a freshman in high school! Hey, to celebrate this historic moment in your middle school lives, you may want to order your Brood XIII T-shirts now!
They will surface when the ground temperature reaches about 60 degrees Fahrenheit. With any luck, they will be here just in time for all those Memorial Day picnics....
More information on Brood XII (and local cicada events) can be found on the following sites:
Great presentation from Indiana University
The Lake County Forest Preserve
The University of Illinois Cicada Page
ABC News (with video)
And, it's not very nice, but you can play Swat the Cicada on your computer.
The University of Maryland even provides cicada recipes for your dining pleasure. It is said they taste like asparagus or clam-flavoured potato.NPR posts just one of their many recipes: (whoa - read the "before you begin")
Disclaimer: the University of Maryland does not advocate eating cicadas without first consulting with your doctor. While many people do eat cicadas, there is no guarantee that they are safe for every person to eat. As with all foods, it is possible that certain individuals will have allergic reactions to substances within the cicada.
1 cup Worcestershire sauce
60 freshly emerged 17-year cicadas
4 eggs, beaten
3 cups flour
Salt and pepper to season the flour
1 cup corn oil or slightly salted butter
Marinate cicadas alive in a sealed container in Worcestershire sauce for several hours. (Note: You can skip this step and go directly to the egg step instead.)
Dip them in the beaten egg, roll them in the seasoned flour and then gently sauté until they are golden brown.