The 17 year - periodical emergence of Magicicada spp. Cicaddas is upon eastern US now - reports from ENN.
New Scientist featured an article in April, and Univ. Michigan's Museum of Zoology has an informative page on the Periodical Cicada.
See also College of Mount St Joseph's Cicada Watch 2004, and pages by Ohio State Uni., Indiana Univ. and Univ. Tennessee.
They adult Cicadas live only 4-5 weeks. This largest emergence ever is believed to be linked to the increase in forest patches as the insect favour forest edges or "suburban savannas".
Update (20 May 2004): See the Baltimore Sun special on Cicadas.