Their planet is dying or something and they all go in different directions, and he crash-lands on Earth on a farm I think. His ship is about the size of a bowling ball to us, and he's the size of an insect. He's exploring the area when a human picks him up, and he uses his laser on the human but the human just thinks it's a bug bite and squashes him.
I think it was like he was writing in a "captain's log" sort of thing.
It was a paperback, I can't remember if it was the first story of the collection but I think it was more in the middle of the book, and I thought they were all the same author but now I'm not sure. I thought it was Asimov but now I'm not sure.