Keep an area free of biters

[Mauslag PIngman]

If I want to keep a clean area free of biters, what is the smallest, cheapest thing I can leave behind to prevent biters from moving in? Would they avoid setting up nests if I drop a couple of iron ingots or do I have to put down an assembler or an inserter? Does it have to be connected to power?

This would be in peaceful mode.

[impetus maximus]

people used small electric poles when this worked. the game mechanic changed.
as long a worm(?) finds and area they can create spawners. your gonna need walls and/or turrets.

[Bushdoctor]

Unfortunately not a single object in the game will prevent aliens from setting up shop in a specific area.
You can either keep the masses back by building large walls with defensive weapons, or if you want to go small,
you can leave a gun turret behind at the spot where you cleared some aliens. They tend to pick the same places for their settlements,
and if you can kill the small batches that are migrating each time, you can keep an area relatively clean.

[Deadly-Bagel]

They only tend to migrate in herds of ~5 biters so as long as you don't trigger a big attack that passes through that area you should be fine to drop a turret or four. Either you'll need to maintain the turrets as they're destroyed or keep pruning the biters past your pollution cloud.

[MalcolmCooks]

This is good info thanks