Seeker Swarm

Seeker swarms are technological devices used by the mysterious Collectors. These appeared to be small brown insects that are deployed on a target planet by their ships. Once released, the swarms sought any living target and stung them leaving their prey in a paralytic stasis-like state. This allows the Collectors to disable the populace of entire colonies whereupon they move in and gather the bodies for transportation.

In the aftermath of the Battle of the Citadel, the Collectors made full use of their seeker swarms on human colonies and began abducting their inhabitants. One such planet was Freedom's Progress where all the humans were taken except for a single quarian who was on his Pilgrimage. Though mentally unbalanced by the encounter, he had managed to record the actions of the seeker swarms which was later provided to Commander Shepard who had begun working for Cerberus to stop the recent raids against Systems Alliance worlds.

After an analysis of the video, the Illusive Man asked for Shepard to find Mordin Solus and use his scientific expertise to create a vaccine to repel the paralytic effects of the seeker swarms.