You've probably heard of the "7-year itch." But how about a 17-year itch? National Geographic tells us about "insects that spend most of their lives as nymphs, burrowed underground and sucking sap from tree roots. They emerge once every 17 years, transform into adults, do the business of reproduction, and then die." These insects are cicadas, and they're itching to take a bite out of your tender trees and shrubs. A brood is due to launch a 2004 cicada invasion this May in the Eastern U.S. Tomorrow I'll have more information about the 2004 cicada invasion.