I want to share something I've learned about Onnet forest.

There are 4 rooms in total.
Each room has 3 doors you can enter (disregarding the door on the bottom of the room).
1 of each of these doors will take you to the next room, else, it'll take you to the previous room (the same room if the room you left was the first room).
Each time you enter and exit the forest, the door arrangement will randomize.

The trick I've learned is to keep track of the number door you entered for each room.
Try to observe who's in each room to see if you're choosing the right doors.
Once you memorize which doors take you to the next room until you find the witch, memorize it. Use this to your advantage to go between room to room.

If all fails, exit the forest and enter it again and try to find the correct doors again.

The room most void of players will usually be the third room since it's hard for people to get to if they don't know how to navigate the forest.

Basically, if you're having trouble getting bugs, try to go through the rooms with your horse to see if there's any bugs that will be easier to catch.

Hope this helps.