Decula Dilemma
Decula cicadas are incredibly difficult to identify. M. septendecula presence in DuPage Co. is still questionable. There have been many reports of Decula cicadas throughout the area, however, without audio confirmation, it is nearly impossible to confirm a cicada as Decula due to the high variability of Cassin's (M. cassinii) in the region.
iNaturalist cicada communiy expert, @weecorbie, has been incredibly helpful in diligently reviewing each Decula observation. They even visited the region to look at cicadas in some of the forest preserves to get a greater understanding of the variability. It turns out that many Cassin's cicadas are retaining orange edging on their abdomens after their exoskeletons harden. The orange edging often slightly fades to black in the center of the abdomen, a big clue that the cicada is not a Decula. Additionally, there have been many "dark pharaohs", or M. septendecim that show brown rather than orange coloration. These have been tripping up identifiers as well.
All in all, there has not been a confirmed Decula in the forest preserves yet. There are many strong candidates, however, they will need additional review. Please keep taking picture of Decula cicada candidates and we will keep reviewing them!
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Thanks for this journal post, Glenn! For those wanting to find septendecula in Brood XIII, @sbrobeson captured two verifiable recordings of calls (particularly this one: https://www.inaturalist.org/observations/223296575) from the Parklands preserves along the Mackinaw River north of Normal, IL. This population was also recorded in 2007. I believe these records constitute the best evidence of the continued presence of the species on the periphery of Brood XIII's range.
Sound recordings are particularly important for verification; ideally, they should capture the whole call structure, so longer recordings (30 sec to 1-2 min) are best.
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