Dubster, he stuffs his egg sack with food when he eats!?
Don't think so! This is his mouse and he can't lay eggs in there for he jumps first on the head and kills the victim,then he turns the victim into a zombie! They created two animations to show this! The scientist fighting against one headcrab and kills him then the second one jumps on the scientist's head and kills the him!
And the second is a headcrab sitting on a scientist's head!