On Friday one of my new interns, Deanna, found these pupae on the leaf of the nanking cherry tree while we were picking. I placed it in a container and waited to see if something would emerge. Sure enough on Monday tiny black bee like critters crawled out. I took photos and sent to them to my new friend, entomologist at UGA, Dr. John Ruberson. This is the response I got from him today.
"Interesting pictures. Thanks for passing them along! I don't know exactly what they are, but they are parasitic wasps in the Superfamily Chalcidoidea, most likely a species in the family Eulophidae, and possibly in the genus Euplectrus. If so, then they have killed a caterpillar of some sort and left the host before it died and fell from the plant. Euplectrus wasps lay eggs on the outside of their hosts, and develop externally as larvae until they pupate off of the host."I did some research and found this further information on http://bugguide.net
Euplectrus has interesting pupation habits. When the larvae finish feeding on the host and have completely sucked out the fluid contents, they leave the dorsal position and seek the underside of the deflated host, where they arrange themselves transversely, in a single orderly row in some cases, and prepare to pupate. A light weblike cocoon is formed which binds the host remains to the leaf, the latter thus serving as a protective covering. Several authors have called attention to the fact that the material from which the cocoon is spun is derived from the Malpighian tubules rather than from the salivary glands and that the slender tapering tip of the abdomen of the larva serves as an "arm" in the construction. The meconium is cast by the prepupa, and sometimes it is ejected from the cocoon. The pupa lies upon its dorsum and is attached to the substrate by means of the last larval exuvium, which envelops the tip of the abdomen.The yellow stuff is the meconium, or waste, cast off by the larvae before they pupate. The black structures are the pupae.
I am always excited to find new warriors in the battle to grow food.