COLLEGE PARK, Md. (AP) — Experts in Maryland say thousands of cicadas are unexpectedly hatching off-schedule.

Local news outlets report cicadas recently emerging in Maryland have surprised experts as they've hatched earlier than the usual time of late May and before their cycles of 13 and 17 years. Scientists are working now to determine what brood the bugs belong to and why they are hatching sooner.

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University of Maryland etymologist Mike Raupp says experts aren't sure why off-schedule hatching happens but it's been documented several times prior. He says the phenomenon is known to occur in Brood X, which is expected to appear in 2021.

Maryland last saw Brood X in 2004 and some hatched early in 2000.

The cicadas could also be in Brood VI, now appearing in parts of Georgia and the Carolinas.