What criteria did you use to ID this to species? The only external criteria I know to be diagnostic is the presence of longer white hairs on the FW of male specimens of juvenalis that must be viewed under magnification for length (also present in some horatius, but fewer and slightly shorter).

The amount of gray/white and/or spots on wing maculation is all in the "usually looks like" category but not diagnostic. Similar with the presence of white scales behind the eyes - almost always seen in horatius, but there are numerous juvenalis (identified by genitalic dissection) that also have the white scaling behind the eye, keeping it from being a definitively diagnostic criteria. (insights from Dr. John Burns on these criteria and their reliability, and the importance of genitalic dissection in Erynnis)

So I wanted to see if you had something else, something new or recently published I've missed, that you used to identify this specimen from the photo.

I agree that it "looks like" juvenalis at a quick glance, and you may very well be correct, but if we only go by the less reliable "typically looks like" criteria, we'd have:

- the extensive gray on the FW and the white scaling behind the eye pointing to horatius
- while the (apparent) long white hairs scattered on the FW and the appearance of the HW pointing to juvenalis.

How did you determine between those two pairs of characteristics?

Jason, I agree with the characteristics which you described but used location as the determining factor since it is my understanding that E. Horatius is not resident here.

I do not consider this specimen to exhibit much graying or ticking of forewing. Juvenal's almost always have extensive gray ticking but can be worn away with age. This specimen shows orange clubs which indicates an aged individual. Horace's are variable in amount of gray ticking. Photos often add to variation by angle, lighting and quality.

I often use the white eye ring as an indicator since Juvenal's show little if any white. The lack of eye ring white is a good indicator of Juvenal's whereas a broad wide proximal band at the eye base indicates Horace's. This specimen has a narrow white proximal eye band which is not definitive.

Many of the Horace's specimens in BofA are misidentified and can only add to the confusion of identifying species based upon variable characteristics.

This specimen looks like Horace's to me but I am not aware that it is present at this location.

>> "used location as the determining factor since it is my understanding that E. Horatius is not resident here."

I'm aware of horatius being in southern Ontario, so I thought that would be a factor, but given that they don't reside year round, juvenalis would be more common, thus more likely.

I've often hesitated to use the white around the eye, other than for the clinch factor for an already pretty confident ID, given that it can be on both species, and from specimen to specimen, can be rather ambiguous. Do you tend to only place more weight on that characteristic in making an ID when it is clearly more prominent?

>> "Many of the Horace's specimens in BofA are misidentified..."

I'm not sure I necessarily agree with that regarding the pinned specimens, as they've done some due diligence of the pinned Erynnis by identifying several by dissection and genitalia, and then used those to help identify others - though I'm sure some mis-IDs make it through.

>> "This specimen looks like Horace's to me but I am not aware that it is present at this location."

That's what I thought too, which is why I've been hesitant to commit to species. My first thought when seeing the thumbnail was juvenalis, but when I took a closer look it looked more like horatius. And yet, horatius apparently only strays into southern Ontario so I was unsure the best placement for this.

I imagine with the location that we'd have to side with the numbers and lean to the more common species in the area, meaning you have it right at juvenalis, but this one definitely gave me pause.

Thanks for giving me some more details, I appreciate the conversation.

I do use either the lack of white or prominent wide white basal eye band to confirm ID along with other characteristics, season, and local. Of course visibility can be affected by image angle / view and mixed degrees of white which usually negates it's use in identification.
My reference to BofA was based upon photo images and not specimens.

Thank you very much for your help, Jason. Much appreciated.

I wish I could help ID to species, but this genus is notoriously difficult to ID to species based on photos.