The Virii are the red triangular shaped creatures often found wandering given areas in tightly packed groups. These are the weakest of the enemy types and most often seen, and the first seen upon beginning a new game in Darwinia. These enemies are spawned from other viruses, such as the Triffid Eggs and Spore Generator eggs one they are “fertilized” with either an enemy or friendly soul. The Virii are rather dumb enemies, and will mindlessly zigzag towards your units once they get close enough.
One tactic that works very well on Virii in Darwinia is to send a Squad in as bait, ordered to walk directly through a large cluster of them, then controlling a second squad that follows the first closely. Since the Squads are slightly faster than the Virii, and the Virii have to be under their target for a moment before causing damage, the front unit will often be able to do this unscathed. The resulting effect causes all the Virii to stack over one another in a line trailing the first squad, meaning laser cover fire placed directly over the advance squad by the second, will allow you to clear large batches with ease, while also making it easier for your Engineers to collect the resulting field of souls.
Virii tend to work in tandem with Spore Generators, as the two serve essential functions for the other. Spore Generators will often lay empty eggs when they hover close to the ground, and when there are these eggs available, Virii will move towards nearby free floating souls, pick them up, carry them over to the egg and plant them within. The Virii can only carry a single soul at a time, but with the typical large batches of them, can often fertilize a field of eggs very quickly. These eggs can be fertilized with green or red souls, and if they are, will soon hatch into more Virii. This means losing a battle to Virii and leaving behind souls can easily lead to their numbers being restored or even further strengthened if not dealt with by additional forces swiftly. You will find Virii in every level of Darwinia except for the Biosphere level.