The vihranen were insectoid animals native to New Romulus. They have a powerful stinger capable of piercing even thick armor. Romulan researchers believed the stingers were developed in defense of predators. There significance to the New Romulan ecosystem was uncertain, thus the Romulans refrained from wiping them out. (STO mission: "New Romulus: Staging Area") Vihranen formed swarms and usually stayed in place rather than moving around. They attacked disturbers only when they entered the swarm and ignored interlopers who were in close proximity but stayed outside. These swarms were of green color. (STO mission: "New Romulus: Vastam Peaks").
The Romulan and Reman people returned to New Romulus in 2409 after the radiation had diminished so far that humanoid life was possible once more. They began to explore the landscape and observe the wildlife. (STO mission: "The Search for New Romulus")
The Romulans began to build a new city at the site where their ancestors first landed on New Romulus after the Sundering. The Staging Area was setup in front of the city gates. Occasionally, vihranen swarms would descend onto the staging area. Starfleet, KDF and RRF forces used insect repellant to get rid of these swarms. (STO mission: "New Romulus: Staging Area")
The vihranen were most common in the Vastam Peaks, a mountain range to the east of the city. Subcommander Avran provided insect repellant to officers of the Romulan Republic and its allies. (STO mission: "New Romulus: Vastam Peaks")