A near extinct species or rather group of species. From the Tzen records it is known that three types existed. The Ants, we think are degenerate decedents of the Rrell. The "Wasps" and the "Hoppers" No ground archeology of the latter two has been found. Bodies have been recovered from Deep space battle sites.
The most is known of the Ants. Archeology of the Ants was found deep under the E coli world. It is still being investigated. There is also the near Oz slow ship which is being investigated.
They are xenophobic to a great degree, as far as vertebrates are concerned. They are a totalitarian technocratic nightmare that works for them. They see anything outside that narrow idea as dangerous and something that must be stopped.
Reproduction is limited to a few members of any hive and tightly controlled. The latter could well be a reaction to a ship environment.
From the studies on the slow ship we believe that not every member of the species is fully sentient. The base worker cast behaves like smart animals.
The only things known of the Wasps are from desiccated bodies recovered from a battle wreck. Their computers were simple, and broken. The Wasps have wings ,and we don't know if they are functional and under what circumstances. Nothing is known of their society.
From examination of the bodies they also look to be a hive species with limited reproduction and physical casts
Again a wrecked Hopper ship is the other thing we have of the Hoppers. They are wingless. In general they have the largest brains of any of the known Bugs. And from the bodies it looks as if every member of the species has fully functional genitals.