Emerged from a frass-covered cocoon in a mine in a shagbark hickory leaf (the one pictured on p. 347 of
(1), which should make this
P. caryaealbella or
P. olivaeformis. Looks pretty similar to the latter, but I haven't found an image of the former to compare.
The mine was collected on 9/23/2008; the moth probably emerged the following spring (all I know is I photographed it on 5/1/2010).