17-year cicadas and lanternflies to emerge around same time, in a 1st for Lehigh Valley Updated Mar 18, 2021; Posted Mar 15, 2021 A mature adult periodical cicada is shown on the right along with a casing on the left, June 10, 2013, in Washington Township, Northampton County.Bill Adams file photo | For lehighvalleylive.com Facebook Share Leafy confines in and around the Lehigh Valley are about to be abuzz with the return of 17-year cicadas. That means a first for the region, since their emergence is expect to overlap with the hatch of the destructive pest known as the spotted lanternfly. Local communities last saw periodical cicadas -- we’re not talking the annual ones that come out each summer -- in 2013. Periodical cicadas are grouped in broods, and that year brought out the 17-year cicadas’ Brood II in areas including the Slate Belt.