them/1954

The little girl wound up in a mental hospital, Central; that's where she was snapped out of her shock by Dr. Harold Medford passing a cup of formic acid under her nose. She snapped out of it, and began screaming, "Them! Them!" and crying.

As for why Sgt. Peterson didn't simply grab the flame-thrower gun and incinerate the ant before it reached him, well, you need to know a little bit about flame-throwers, Lumpy. To use one correctly, it has to be on your back, and you have to lean forward and brace yourself against the recoil and heat of the flame-jet; if you don't, you might be knocked off-balance and incinerated by your own flame-jet coming back at you. The character Peterson may have been a Marine in WWII or Korea and checked out thoroughly on flame-throwers (actor James Whitmore was, in fact, a WWII Marine veteran, and was trained on flame-throwers), so he knew the danger of possibly being burned alive; that's why he helped the boy into the storm drain and then tried to get up there himself. He removed the flame-thrower because it was so heavy; with the weapon strapped to his back, he would not have been able to heft himself up into the storm drain. But of course, he under-estimated the speed with which the ant could move ... with the results as depicted on film.