<p>Brood XIII Magicicada</p><p>Brood XIII (also known as Brood 13 or Northern Illinois Brood) is one of the broods of periodical cicadas that appear regularly throughout the midwestern United States. Every 17 years, Brood XIII tunnels en masse to the surface of the ground, lays eggs, and then dies off in several weeks. Although entomologist C. L. Marlatt published an account in 1907 in which he argued for the existence of thirty broods, over the years a number have been consolidated and only fifteen are recognized today as being distinct. Brood XIII is among the twelve different broods with a 17-year cycle. Its last appearance was in the spring and early summer of 2007 throughout an area roughly enclosed by northern Illinois, eastern Iowa, southern Wisconsin, and a narrow strip of Indiana bordering Lake Michigan and Michigan. It also emerged in 1939, 1956, 1973 and 1990, and it will emerge again in 2024 and 2041. Cicada juveniles are called "nymphs" and live underground, sucking root fluids for food. Their burrows are found anywhere from several inches to a few feet underground, depending on nymphal age and the nature of the soil. Newly-emerged cicadas work their way up into the trees and spend roughly four to six days as "teneral" adults before they harden completely. After their short teneral period, males begin producing species-specific calling songs and form aggregations (choruses) that are sexually attractive to females. Males in these choruses alternate bouts of singing with short flights until they locate receptive females. Contrary to popular belief, adults do feed -- by sucking plant fluids. Mated females excavate a series of Y-shaped eggnests in living twigs and lay up to twenty eggs in each nest. A female may lay as many as 600 eggs. The adult emergence lasts for about four to six weeks after the appearance of the first nymphs. Six to ten weeks or so after oviposition, in midsummer, the eggs hatch and the nymphs drop from the trees, burrow underground, locate a suitable rootlet for feeding, and begin their long 13- or 17-year development. The 1½ inch long black adult bugs do not sting or bite, nor do they carry disease or harm vegetation. Birds and other predators feast on the cicadas, but their huge numbers help ensure that many individuals will survive and reproduce. They can number up to several hundred thousand per acre. </p>