I watched this movie on TV in California roughly 20 years ago. I can't remember if it was in black and white, but it's possible.
The bits and pieces I remember were that a man (he might've been in his 20s?) had an ant farm of what appeared to be regular ants. I'm pretty sure he shortly fell into this ant farm and was eaten. I think I recall a shot of him covered in ants to the point of being unidentifiable. The ants got bigger and escaped, proceeding to eat just about anyone and anything all the while growing bigger without end.
The main characters were a man and a woman (that's all I've got about them, sorry. I was ~6 at the time, so I really only remember details about the ants). Near the end of the movie, I think these two people were hiding in a building as the ants were literally eating it apart. They were pretty big at this point.
Then, I had to go to bed. I don't know what happens after that. I've spent the last 20 years expecting I may someday stumble into this movie again and I'll be able to finish it, but to no avail.
Can anyone here help me identify what movie this is?