Wraith supply ship

Wraith supply ships are vessels which carry cocooned humans to other parts of the Wraith fleet. They are usually used when the Wraith are in a long battle, and need to be resupplied with humans to feed upon. The Atlantis Expedition discovered a crashed supply ship on the Light Bugs' Planet in the Lantean system, one which was intended to feed the Wraith battling the Lanteans who were defending Atlantis.

The vessel isn't a class of its own, but is in fact a modified Wraith cruiser, as stated by Lt. Col. John Sheppard.