Demon Star — B.V. Larson

Three stars, three worlds, three civilizations…one massive war. In a triple star system, not all planets are equal. When the Demon Star swings closest in her orbit, the Insectoids always invade. They raid the inner worlds with grim regularity, riding hordes of stealth ships in ever-growing waves. Their mission is to destroy all opposition―alien, human, or otherwise.

Cody Riggs, lost among an endless chain of interstellar rings, flies his task force of starships into the middle of an eternal struggle for survival between three civilizations. He takes it upon himself to help the more peaceful worlds, but only manages to bring disaster to all humanity.