Hi Ned, this looks like a hairstreak (Jalmenus) pupa. What sort of plant was it on? If it is possible to return to the site, check for other pupae and any hairstreak eggs or even larvae on the same plant, or nearby plants.
Hi Suzi, I can probably head back to the site this weekend. I'll see if I can find anything else of the kind and find what plant it was on. Thanks, Ned