If ductwork is located in the attic make sure to insulate it as well to reduce heat loss and gain while passing through this unfinished space.
Difference between attic and scuttle.
The goal with an unfinished attic is to seal it off from the main living space below.
Probably a bird or squirrels.
For air to move there must a path hole in the ceiling crack in the drywall poorly sealed attic scuttle etc and a difference in pressure.
The bird will die after a few days if it can t get out.
This means you should insulate between and over the floor joists.
To make sure that it isn t just a gaping obvious hole in a ceiling it often has a removable.
Don t forget to also insulate the attic hatch.
The rule here is simple.
You can buy some poison to kill the squirrels or rats in a garden centre don t let them stay up there as they can do lots of damage to the wiring etc if they remain.
Check this out for more info.