The Menoptra and Zarbi are the original inhabitants of the planet Vortis. The Zarbi were little more than cattle, with no speech or motives of their own, and the two groups lived in peace. Then the Animus arrived and began to sap the life of the planet, draining it of water, destroying the flower forests and taking control of the Zarbi. They became hostile and attacked the Menoptra, who were forced to flee the planet and live on one of the new moons that had been appeared, as they had no weapons. But they were not designed for life on this new moon, and their wings began to grow weaker. They eventually decided that there was no other course of action than to retake Vortis, and began massing in space for an attack.
The Menoptra look like giant humanoid butterflies. They are graceful, gentle, and overall pacifistic. Their bodies are black with rings of colored fur, they have long antennae, and two sets of iridescent wings unfold from their back. They can actually fly with these wings, even through space. Like moths, Menoptra are attracted to bright lights. Menoptra have a highly developed system of body language, mainly conveyed through the use of their arms. For example, challenging the authority of another Menoptra seems to involve a hissing sound combined with a snake-like lash with both arms. The Menoptra are scientifically talented, constructing crystalline transmitters and a device known as the isoptope, or living cell destructor, which they designed to destroy the Animus by causing its cells to grow inward and die. Menoptra also have a difficult time with foreign names - they convert Ian to "Hran" and Barbara to "Abara".
Some Menoptra retreated underground, where their wings withered and they became highly sensitive to light. These Menoptera began calling themselves Optera, and forgot that they had once been like the others above ground. In fact, they began worshipping the Menoptra. The Optera are simple creatures, rather larval in appearance, and as they are unable to stand upright, they hop from place to place rather than walking. As they live underground, they have become very adept at digging.
The Zarbi look like large, bipedal ants. They possess a set of vice-like mandibles which they use to manipulate objects. They communicate using high-pitched staccato noises. Only intelligent under the control of the Animus, the Zarbi cannot even right themselves if toppled. They are easily frightened, particularly by spiders. The Zarbi can put others under the control of the Animus by putting a gold wishbone-shaped controlling device around their neck. Prisoners are often taken to the Crater of Needles - if they are Menoptra, their wings are ripped off to prevent them escaping - where they feed vegetable matter into the acid streams, which causes the Animus' headquarters, the Carcinome, to grow. For weapons, the Zarbi utilize larvae guns, small grubs that fire from their long snouts. If they are inside the Carcinome, there are also guns in the walls that cover their target in sticky, stinging webs.
When the TARDIS crew defeated the Animus, the Zarbi reverted to their mindless behavior, and the Menoptra were able to colonize Vortis once again.
