Click below to reveal the answers to this weeks’ quiz!
The butterfly on the left is the Eyed Brown. The butterfly on the right is the closely related (and looking) Appalachian Brown.
These two species can be difficult to tell apart, especially as they are fluttering by you in the field but if you look close, there are a few key features to pay attention to.
A) The Eyes.
The brown outer ring of the eye spots on the Eyed Brown are usually touching with the white outer layer forming a “peapod” around them. On the eye spots of the Appalachian Brown, the brown outer rings are separated from one another by the white outer layer.
B) The PM Line in the second cell from the bottom
This outer, hind wing line is more jagged in this cell on the Eyed Brown and usually looks smoother on the Appalachian Brown. This difference can also be seen on the PM line on the fore wing, which is also more likely to have jagged peaks on the Eyed Brown and have a smoother appearance on the Appalachian Brown.
C) A less reliable characteristic: The Basal Line.
This is not illustrated well by these pictures because the field marks are swapped between the species. This shows that it is always important to compare multiple field marks when making IDs, especially among closely related species.
The first cell from the top of the inner basal line on the hind wing has a zig zag towards the body on the Appalachian Brown pictured here, typically a characteristic of the Eyed Brown. By contrast, on the Eyed Brown here, the line through this cell is relatively smooth, a typical characteristic of the Appalachian Brown!
Both species use Sedges as host plants. The Appalachian Brown is a little less commonly found in Vermont and more likely to be found along the western edge of the state. The Eyed Brown can be found across the state.
Photos by:
Eyed Brown by Jeff Cherry (iNaturalist)
Appalchian Brown by Jason Swanson (iNaturalist)
Ready for next weeks’ quiz? Click here!