Using a sharp knife, cut corn kernels from the cob into a large bowl. Into the same bowl, scrape the cobs with the dull side of the knife to release any juice left in the cob. Set aside.

Melt butter in a large skillet over medium heat. Add the onion, bell pepper and tomatoes, and cook and stir until the onion is tender, about 10 minutes. Add the corn, crawfish, green onions, sugar, salt, black pepper, and cayenne and cook and stir until corn is tender, about 10 minutes.