Phase IV is not your average movie experience. Definitely not for everyone, so, see it if you get the chance (Last I saw it was a 1997 airing on The Sci-Fi Channel.) and decide if it's for you.
It's even hard to generalize WHAT the movie is about. On the surface, a colony of ants has gained a heightened level of intelligence and has apparently decided to drive out the local people. A group of surviving scientists, who were examining the ant phenomenon, rescue a wandering woman, and they become "trapped" in the "laboratory." The lead researcher then goes nutters over trying to determine what the ants are doing and getting nowhere because, well, ants and humans just aren't natural conversationalists. And the story ends... well, it just ends. What did the ants want? Did they take over the woman's body at the end? Did they the one surviving scientist, or, did he "join" them, just come to reason with them, what? Plus, what ARE the other three "Phases?"
Now, I first saw this film on Beta in 1985 and on VHS many time since, the last being the aforementioned 1997 airing. I've read the reviews here, and, WHERE are people getting the alien intelligence taking over the ants from?! I've been watching this movie for 15 plus years, and, I can't recall any aliens mentioned. An alien influence on the ants WOULD make a bit more sensical motivation for the ants, but, I don't recall this stated even as a theory anywhere in the movie. I welcome anyone to e-mail me and let me know where it is in the film, because, I may have just failed to catch it.
So, why would I recommend it? This movie manages to effectively pull you into the story without any of the excess baggage one would expect from a nature gets its revenge picture. No drawn out "battle" sequences, like "Empire Of The Ants." The event has happened, so, there's no need to express it with cheap special effects. The story hinges instead on the aftermath, how people deal with it, the scientific community's response, all the time presenting a prevailing air of mystery as to why the ants did it. The casual viewer will be disappointed by its rather quizzical ending because it doesn't "resolve" the question of what the ants want or were doing in a clean cut package. In fact, it doesn't GIVE an answer. It opens up the floor to debate, so to speak, where your own questions about it allow you to formulate your own "message" from the ending. Can we live with the ants? Can the ants live with us? Do either sides want to?
Many would also find this film boring because of the lack of "action" sequences until the end, pretty much summed up when the nutter scientist is consumed in a pit of ants. Instead, the film builds up suspense with effective small shots of the ants themselves. Ants moving through technical equipment to "sabotage" it. Ants moving through their tunnels, reflecting a genuine "sinister" sense, a sort of "What are they planning, if anything?" atmosphere. Ants moving over furniture, people. Nothing over done with an army of ants crawling all over the place, people screaming as they drown in a flood of insects (Save the one scientist, I suppose.) It doesn't dumb itself down with exploitive action sequences.
In the end, the film doesn't insult a viewer's intelligence. IF someone doesn't get anything out of about it, the film just lets them be. For others, it opens up the floor with unresolved questions, but, does not hinge on them, like so many cop out endings. You're left to reach your own conclusions, but not as a crutch, to avoid having to write an ending or a low budget, etc.
An interesting film if you can ever find it. If you do, watch it and decide for yourself. It's one of the few movies made that lets you choose whether to like it or not, and goes along with that.
Review by Dr Wily from the Internet Movie Database.