EDIT: There is a first stage for this invasion. During the first case, there will be insectoid scouts in a regular landscape around Greenshore. They appear in small groups of two and the invasion can be halted if they are killed in certain numbers during that day. The landscape changes if they are left alone, with a bigger invasion in the next day.
Thanks @Mogh for the heads up and the awesome screenshot!!
Your best way of discovering when it is happening is simply by leaving a character inside the watchtower near NPC Tokel. You will be able to spot if the blueberry bushes are destroyed from the upstairs inside, which will be great for you since you can log on another main character pretty fast and go after the Insectoid Scouts! Normal blueberry bushes means that there is no Insectoid Scout world change around!
You can find Tokel here: https://www.tibiawiki.com.br/wiki/mapa#32255,32055,7:1
I show the place where you should leave the noobcharacter in this video by the end. I actually log in the exactly location where you should stay: https://www.youtube.com/watch?v=Eg5IxcGvlAc
I also show in this video the area and even a hole with 4 Insectoid Scouts!
HOLE LOCATION HERE: https://tibia.fandom.com/wiki/Mapper?coords=126.4-125.102-7-1-1-1
- SOURCES USED FOR MY ANSWER: https://tibia.fandom.com/