Vanna is an alien who invaded Earth. She released the giant insects who ate most of the world’s population.
One time two of her underlings found an Earthman and brought him before her. Vanna taught the prisoner hoping to get some use out of him. He learned too well however and escaped. He witnessed how Vanna bedded the Goliath, one of giant insects, and his two male subjects. While Vanna was on the bridge of her ship, the prisoner burst through the door and killed the males. He also hit the launch systems and the spaceship took off from Earth. They hit an asteroid with breathable atmosphere. Vanna survived, but kept away from the prisoner.
When the human killed Goliath, it broke Vanna, as she truly loved him. Days later Vanna herself died, as the grub growing inside her ate its way out.