Insect sprits were the Invae from Earthdawn...a precursor spirit to the Horrors arrival but not horrors. (It's there arrival that got the IE's and Dragons in a huff and alerted them to the "bridge" I believe.)
The only statted horror like creatures in SR were the two types of creatures that attended Mr.Darke (Oscuro) in the Harlequins Back adventure.
If insect spirits are a precursor to Horrors, then I suggest researching the Chicago quarrentine. Also, there has been a lot if activity in Hong Kong recently regarding Ares Firewatch Teams. Being that Hong Kong's astral energies are extremely unstable, because of corp manipulation, this might explain some of the rumors about The Yama Kings who inhabit Kowloon Walled City. With all the spikes and astral shallows appearing and dissappearing all throughout Hong Kong, I would take a guess that Horrors have began to return...
[Update]: The Ares Firewatch teams, specifically the bug hunters, were called in when the Hong Kong police conducted raids recently.
Also, there seem to be named Yama Kings, or Horrors, working their powers in Kowloon Walled City.
Chih-Shiang: judge of souls, makes residents of Kowloon Walled City believe they are there for bad karma from past lives.
The Ebony Queen Lam Vy: teaches her followers to hide from the Yama Kings, until they hide so well they become roaches.
Fu Mang, the Serpent of the Setting Sun: Promises wealth to those who bring him 44 hearts of family and friends, removed when the victim is alive.
It is speculated that between 10-20 of these Yama Kings reside in Kowloon Walled City. All this info is from Runner Havens.