This 35mm screening is part of the Experiments in Living season at the Barbican Centre. You can reed the full details here.
Chicago Reader review:
David Cronenberg made his commercial debut with this aggressively unpleasant 1975 horror film on the theme of sexual disgust. A swinging-singles apartment building is overrun by slimy little creatures who carry an exotic form of VD. Hard, if not impossible, to take, the film nevertheless represents a major turning point in the genre—the discovery of the body itself as a source of terror. Cronenberg's later films are superior in technique, though not necessarily in intensity.
Here (and above) is the trailer.