Ace title designer Saul Bass (and ace designer of all sorts of other things) directed only one feature, Phase IV (1974). Notoriously hard to see, it was tracked down by the TCM Classic Film Festival in a rare, original release print, scratched and kind of pink, but a real oddball treasure.
Star Michael Murphy was present to introduce the screening. He was pretty down on the picture. He hated his own performance, and was fairly dismissive of the acting in general, pointing out that Bass’s undeniable forte was the visuals, and that the actors were left largely to their own devices. 
He also related how tax breaks took the production all the way to Kenya (substituting for the Arizona desert!); how he was discouraged from building chemistry with his pubescent love interest Lynne Frederick (her English rose innocence could presumably have handled it, since she married Peter Sellers a couple of years later); and how he had to loop the entirety of his dialogue in London in Bass’s absence once photography was over.
Murphy’s apologies for the acting weren’t entirely necessary, but certainly understandable. This is an ideas and visuals piece, rather than a film of dramatic heft. Although far from stellar, he acquits himself adequately, as does Frederick, given little to do but wander around in shock and fear. Nigel Davenport as the near-megalomaniacal scientist with whom Murphy’s linguistics/game theory specialist is studying space-ray-infected ants, is a bearded, burly blowhard after a familiar pattern – as Murphy put it, with Davenport, what you see is what you get.
The characters are hardly well-drawn, but the point is the ants. 
Paramount was expecting a horror movie, and it is indeed horrific in places (so intelligent! so deadly!) Although the weakness of the individual versus the strength of the mass is emphasized, there’s one little chap with a glowing green abdomen who’s particularly troublesome, and too tiny to catch; and en masse they are indeed effective, devouring anything they like within seconds, evolving a poison-resistant strain overnight, and eerily building simple but precisely geometric towers in the desert.
Why are they doing this? Who knows. Maybe Phase IV would have explained (although probably not). Captions for Phases I through III trifurcate the film, with the title appearing only at the very end. Murphy described a montage epilogue that was shot but excised, in which, co-opted by the extraterrestrial ant intelligence, he flies with eagles and such. He rightly pointed out that although the studio may have found it too far out, it would surely have secured the faithful patronage of a particular demographic – everyone was getting loaded back then, he pointed out.
What remains is still pretty trippy, particularly the spacey opening and the synthtastic score. Bass’s visual flair asserts itself in the play of color, light and shapes of the ant-vision, and loads of great macro-photography of their eerie, intelligent industry. Both a product and a casualty of its time (think cheesy ‘70s sci-fi) there’s still enough visual imagination and weirdness of concept to hold the interest, and to make one regret the missing ending. Whether or not it would have justified the rest of the film’s shortcomings cannot be told.
Postscript:
By chance the mythical ending was found, on a shelf, in an archive, and thanks to the inestimable Cinefamily, it was shown for the first time in nearly forty years. It was a very exciting evening. It’s only three or four minutes long, but the excised sequence is jaw-dropping, the succession of mystical-cosmic imagery stunning. The girl gives birth to a second sun. There’s a fish with legs. To try and describe it fully would be to rob it of its magic, and I wouldn’t be able to do it justice. It’s more fantastical and trippy than one could have imagined (and respect must be paid to Brian Gascoigne’s awesome electronic space ant music). Best of all, it’s not even Phase IV: that title was always meant to come up with the credits. The prospect of what is to come is now all the more mind-boggling.