Brood X cicadas begin to show themselves — and their sounds — at Columbus-area Metro Parks Tim Carlin, The Columbus Dispatch The late morning air is humid at Highbanks Metro Park. The shade from the large trees provides a slight reprieve from the heat — but not much. Even before a visitor sees a single cicada, the members of Brood X make their presence in the park known. Their hollow hum reverberates through the trees like a subtle background noise. Their little brown shells line the tree trunks in various clearings and picnic areas, and hundreds of exoskeletons pool around the base of the trees.