If Manly Wellman isn't the greatest sci-fi writer's name, nothing is.
The Dark Destroyers brough a new Ice Age, eh? They used translucent chicken heads. Another novel depicts them like this:
It's almost as if the artists felt a duty to depict the author's work as the author intended. Review:
Earth is invaded by a cold race of beings with very little in common with humanity. Humankind is nearly wiped out except at the equator. Survivors are people who ran away instead of fighting. Earth is destroyed by two types of ray weapons.
Twice the fun!