Scientist Dr. Ernest Hubbs (Nigel Davenport) organises a project to study them and if necessary destroy them as he considers this to be a great threat to humanity.
Recruiting mathematician/information theorist James Lesko (Michael Murphy) they set up a sealed lab adjacent to the colony and begin a battle of wills with the emerging intelligence.
One of those "WTF did I just watch" bits of late night 80s BBC2 television I remembered this distinctly.
Heavy on voiceover and footage of ants crawling it becomes a clash between the two scientists, one wanting to destroy the other wanting to communicate. When a young woman (Lynne Frederick) ends up in the lab it feels like she's just there for decoration.
The ending is bizarre but it's very high on the list of cult 70s movies you must watch. Objectively it's only a 4/10 but it's seminal cult weirdness so watch it anyway.