Bug

Of all the races encountered by Terrans, the Bugs (Mobile Infantry term for the species) are amongst the most incomprehensible. Most races are composed of individuals. The Bugs are not individuals, but rather are units in a vast hive consciousness. They are individually devoted to only one great task: maintenance of the survival of the Hive and its Queen. All they know is Duty, pursued with an instinctive and all encompassing drive ingrained by thousands of generations of selective breeding and genetic perfecting of the qualities desired in each of the three castes.

Brain Bugs

Highly sensitive psionic Adepts who are able to attune themselves (barely) to the thought frequencies of the Bugs have con-firmed that the function of the Brain Bugs is not to lead, but to maintain a psionic link, joining all members/units in the Hive Mind. Only the Hive Mind has awareness and intelligence. Individual units have only instinct to guide them when not in contact with the Hive. Brains act as communicators to express the will of the Hive Mind and to supply information on local situations to the collective consciousness for evaluation and decision. This explains why slaying a Brain Bug leader does not cause permanent confusion. Any replacement can perform literally the same functions of command with the same level of efficiency. Brains do not join in battle themselves. They are, in fact, quite incapable of defending themselves from anything larger than a small dog or cat.

Warriors

Maintaining security of the Hive and its territory, property, and members is the task of the Warrior Caste. They resemble giant soldier ants, armored in chitin and armed with strong mandibles. They must remain in contact with a Brain Bug (usually within 500m) or they will stop still, continue moving in the last direction ordered, or range randomly to and fro. However, blind instinct will send the isolated Warrior into ferocious attack at the sight of any non-Bug vehicle or individual. Any enemy within 100m of an undirected Warrior can expect to be locked in close combat. Nor is Warrior morale a problem. Every Bug Warrior follows orders in the face of impossible odds. The Bug leadership regards them as expendable as the human leader regards the ammunition fired by his men.

When first encountered (in the time period covered by Space Marines), the Bugs were rather primitively armed with single fire blast rifles and other early Tech/7 weapons. Later on, elite swarms of Warriors are encountered with fairly up-to-date weapons and protection from gas, etc. The Hive Minds have apparently recognized the threat and have acted to increase the fighting efficiency of their Warriors.

Workers

Workers perform all other duties in the Hive, technical and otherwise. They are the most numerous members of the Hive. All are non-combatants bred for work, not war. Personnel who have not encountered Bugs before will confuse them for Warriors 75% of the time, while experienced personnel are still confused 25% of the time. The Bugs often send in diversionary attacks of Workers to draw enemy fire. They also mix Warriors into a mob of Workers to divide enemy fire. Workers evidence technical expertise.

The Hive

Bugs live underground in vast tunnel and chamber complexes covering many square kilometers, and extending several thousand meters below the surface. Deep in the Hive the Royal Chambers shelter the Queen, who lays hundreds of eggs per day. Each Hive is apparently independent of the others, but there is a good deal of co-operation despite the lack of central authority.

General

Bugs prefer Steppe Planets with fairly warm temperatures, but they do not like desert conditions. They have unbelievably high tolerances to most noxious gases, yet are susceptible to high silica dust concentrations in the air. Radiation is tolerated with little observable effect. Unless struck in the head or body, wounds have virtually no effect upon the life force of the creatures, and shock effects simply do not occur even from mortal hits. Stun Beams, Neuronic Whips, and Paralysis Rods have no effect, but Coagulators will penetrate their chitin armor automatically.