Giant Gray Moth (Cymatophora approximaria) range and flight summary using iNaturalist data

The Giant Gray Moth has been an interest of mine for several years. It is unique in that is has a short flight window in the fall, and until recently, was not recognized by the iNaturalist computer vision models. This left many observations at a higher taxa level or incorrectly ID'd. Thanks to the help of other iNaturalist users to get these observations to species, the dataset in iNaturalist is providing a more accurate picture of the distribution and flight period of this species.

The figure below combines research grade observations and their corresponding Level IV Ecoregions. I also included a flight chart of those same observations. I marked Abita Springs, LA on the map due to the work of Vernon Brou who has published information on the species from his study site in Louisiana. The dashed line is an approximation of the range I've hand-drawn based on current observations and is for illustrative purposes only.

Interestingly, there is a noticeable gap in the distribution, centered on the Lower Mississippi Alluvial Valley. This is also reflected in the MPG range map. The flight period matches what Brou found in Louisiana, except for a few outlier records in early October and early December. Florida has the latest records, including one 14 Dec and one 16 Dec. Bugguide lists observations from Georgia in late September.

New Jersey is within range based on published information, but none have been reported on iNaturalist, MPG, or Bugguide yet.

Now that the computer vision recognizes Giant Gray Moth, hopefully future observations will be more readily identifiable, and observers in the s.e. US will become more aware of this late fall moth that makes a relatively brief appearance each year.

Giant Gray Moth

Posted on December 02, 2021 08:29 PM by johntrent johntrent


Thank you! Very useful and interesting.

Posted by michael64 over 1 year ago (Flag)

Hey John, great job on this. This species wasn't even on my radar but i'll keep an eye out even though I'm 100 miles away from its known range and in a different ecoregion.

Posted by jeffgarner over 1 year ago (Flag)

Agreed -- this is wonderful!

Posted by sambiology over 1 year ago (Flag)

Fabulous mapping with the ecoregions. I'm hoping to do the same kind of analysis with some Petrophila moths, although I'm toying with the idea that the watershed and stream order data might be appropriate for that genus (with aquatic larvae).

Posted by gcwarbler over 1 year ago (Flag)

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