This was an episode of a radio show called 2000 Plus. The stories were about life after the the year 2000. This episode was first broadcast on May 17, 1950. The story is about a scientist who has invented a growth ray and is using it on insects. He's made a spider as big as "my fist", a housefly as big as a "pack of cigarettes" and a wasp "no bigger than a golf ball". His wife objects but the scientist says not to worry, "they're not giants". Anyway, the scientist goes to a meeting at the university to talk about his invention. Curiously, he brings none of his insects. The wife is left alone and when the grocery delivery boy wants a look at the insects they get accidentally locked inside the lab. While they are there they are confronted by a moth (who I'm guessing is the size of a bag of pretzels) and it terrorizes them until the delivery boy tries to escape. He thinks the moth is trying to kill him. We know this because he yells out, "He's trying to kill me!" before he knocks himself out. Well, it all ends well and everyone is rescued when the scientist comes back home. But the best part is that no one, not the wife, delivery boy, dean of the university or any of the professors or the delivery boys' boss who never comes looking for him ever asks the scientist why the hell he is making giant insects and what possible benefit cigarette pack sized houseflies could be.