That loud buzzing heard across the southern half of Illinois this month?  It's the mating calls of periodical cicadas emerged after spending 13 years underground. Most cicada species emerge after 2 to 5 years, but some species have longer cycles and emerge en masse. According to INHS Entomologist Chris Dietrich we are should consider ourselves fortunate to have those loud inundations of periodical cicadas. "Illinois has five different (periodic) broods, two 13-year and three 17-year," he said. "We're kind of lucky. We get to see them more often than people further west. Cicadas are found mostly in the tropics, but there are 25 to 30 species in Illinois and close to 100 in the U.S."