From the introduction:
The Arachnids are the greatest threat the United Citizens’ Federation has ever faced. The bugs are no simple crude menace but an invader seeking to annihilate the human species and take worlds to expand their empire. Across the light years, the Arachnids threaten the survival of all species in a war of technology against engineered evolution.
Up to now, the Arachnids have remained a faceless, omnipresent enemy, spearheaded by millions of vicious warrior bugs as they spread in waves across each new world.
For the first time, the secrets of the Arachnids are revealed. This book will serve Games Masters wanting to present the Arachnids in the most terrifying way possible, as well as players seeking an edge that will allow their Mobile Infantry trooper to survive just a little longer in battle.