I put some overflow weaner ASF's in a rat rack with 1/2" wire about 6 months ago. I'm still catching them in traps, they're all over the place. Luckily, they were all males, but man, I bet 1/3-1/2 of them escaped on the first night. They weren't small either, more than half grown. They squeezed right through.
Lesson learned, only 3/8" wire for me from now on!
Good luck.