Magicicada Brood X in-hand ID tips?

Seventeen years ago, I didn’t care about id’ing a periodical cicada to species, but thanks to iNat, now I do. With the big emergence about to happen in my area, it’s time to get educated about the differences between:

This page at Cicadamania gives a few pointers and has just a few underside pics for comparison:

I’d appreciate any tips from experienced observers/entomologists here who could help newbies like me start to sort them out. I bet it will aid not just my taking pictures in the field for my own observations, but in helping id the observations that will be coming in here from other folks. For instance, what set of photo angles can give you the easiest way to tell them apart? Are there other obvious distinguishing fieldmarks apart from their undersides? Thanks for advice!

8 Likes gives the best info. As for photo angles, I would make sure to get one of the underside of the abdomen and the area between the eye and wing.

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Thanks! So for the patch between eye/wing, it looks like septendecim has orange, the other two are dark at that spot. From the upperside, can cassini vs septendecula be distinguished in some other way?

For the underside, it looks like septendecim is fairly orangey, cassini fairly dark, septendecula sort of in between those two? Might cassini vs septendecula, or septendecim vs septendecula be harder to tell apart from just the underside depending on the individual’s shading?

edit 3/29 just noticed a recent obs with a ref to a comparison photo set by Sheryl Pollock, very nice!

I don’t think you can ID them to species with just the upperside. You could separate them into septendecim and cassini/septendecula. With the abdomen, septendecim has almost completely orange stripes, septendecula has black stripes with some orange, and cassini has a pretty much completely black abdomen.


Thanks! With that in mind I’m thinking about all the incoming observations we might see with just the upperside- where it’s too tough to call they could just be id’d to Magicicada with a note about the species similarity.

BTW I just remembered that underside shots could lead to bonus observations of Massospora cicadina which is pretty cool. :)


I’m a little late to this conversation, but roshan2010 nailed it when they said that the most important features are on the underside. I’m encouraging people to try to get underside shots for my project ( so that we can get as many species-level IDs as possible. Genus-level IDs are valuable for mapping, but with iNaturalist, we may actually be able to get a better sense of the distribution of species within Brood X. Ventral shots also reveal whether the specimen is male/female, whether a female has mated/oviposited, and whether there’s Massospora infection.

The width of the orange stripes on the abdomen of -decula vs. -decim is the big difference; -decula’s stripes are very narrow, about 1/4 of the width of the segment, while -decim’s are wide, ranging from over 1/3 to nearly the entire segment in very orange individuals. When there’s doubt about the width of the stripes, look at the edge of the pronotum and the pleura (the area underneath the pronotum surrounding the front legs). It’s orange in -decim, but black in -decula.

I’m so excited that more people are getting into Magicicada this year! They really aren’t hard to ID, once you get the knack, but it’s important to keep location and date in mind so as not to mix up 13- and 17-year species.


I would think that since M. septendecim is probably going to be the most common species, a lot of the upperside shots would still be IDable to species as long as they show the area between the wing and eye.

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It is true that the presence of an orange patch is enough to confirm septendecim ID, but unfortunately a lot of folks take completely dorsal photos, and all you can tell from those is that it’s Magicicada. Lateral photos are better, but the ventral shot is the best for ID. Once in a while, especially at the beginning of an emergence, the cicadas can be high up in trees and flighty, but most of the time, there’s no reason not to just grab the bug and snap a pic of the underside. (Maybe after you take that really pretty in situ shot.)

In my two previous experiences with Brood X in and around Cincinnati, cassini was by far the most common species; it seems to do best in open areas and suburban habitats, while septendecim favors deeper woods and high canopies. In Brood IX, there were areas where (surprisingly, to me) -decula was most common.