From the back cover,

"Bugs. Arachnids. Call them what you will, they are the greatest and most terrifying threat Mankind has ever faced. A species so utterly ruthless and alien that they are beyond comprehension. The Arachnid Army Book takes this most compelling threat and reveals a level of detail never before seein inprint."

The Arachnid Army Book provides detailed background, new rules and new unit types for Bug forces in the Starship Troopers miniature game.