The AntsCanada Ant Forum's

A measurement would definitely help... However i disagree with Lasius. I'm leaning towards Formica sp. (possibly subsericea)
And Lasius niger does not exist in America so it's certainly not that

Numbers 3 through 24 are all Lasius niger.
Number 2 looks like a Formica sp.
Number 1 i'm not sure about but i think another kind of Formica sp.

The idea is making a amazon biome, with only native plants and species (both ants and fish) Ah oke sounds cool! Would love to see some pics when you are finished ;) I have some tropical terrariums myself... also wanted to turn them into paludariums with lots of water, sadly my gecko's are very poor ...

im thinking about getting either Fireants, yellow crazy ants or bullet ants of asia (not sure if they can adapt to the large bodie of water), but i'll read up on them before i choose one :) I see you are from Denmark, so why are you only thinking about non-native species if i may ask? Is it not pos...

They are mostly monogynous, sometimes they have 2 queens but they live in seperate areas of the nest... So i suggest founding all 3 of them alone.

I don't think Messor barbarus lives in the UK at all. They are a mediterranean species as far as i know.

I see... At least i got the genus right this time

I'm not entirely sure what you mean... But it could be that you are looking at the skin underneath the scales... When the gasters are small you will only see the outside exoskeleton but when they expand these "scales" will not stretch so in stead they will sort of drift apart allowing you to see wha...

Looks like Formica fusca to me

I can only look at about half of the pictures, the other ones need permission.
From what i can see it does look like a Lasius sp. But i think 6mm is a bit small for L. niger...
Maybe someone else can tell you more