Chicago’s cicada swarm is upon us after a 17-year hiatus. City officials have warned that 17 and 13-year insects from Brood XIII are due to emerge around late April or early May, and will be sticking around until early June. Some researchers have noted an early emergence - the Morton Arboretum in Lisle said some had already arrived - but Mark Hurley from the Forest Preserve District of Lake County told WTTW sightings may be nymphs flushed from their homes by rain. Morton Arboretum advised that those with vulnerable plants use tulle to protect them from the creatures.