If ants can't see red. Why are some ants red in colour?

[ClashOwenBash]

It's a question that recently came to my mind and I've been wondering if anyone can enlighten me. (p.s. I know some ants can see red)

[AntsDakota]

It's a question that recently came to my mind and I've been wondering if anyone can enlighten me. (p.s. I know some ants can see red)

Ants don't operate on sight. Therefore color doesn't matter.

[Hunter36o]

And all ants can see red at a certain level. Some just have more trouble then others. And it is also a combination of red colour levels and light levels at the same time.
For example Lasius Niger's have possibly the best sight in terms of red. You needs a very low red level with less light to trick them into thinking it's dark where as Myrmica have very bad eye sight in terms of red and a keeper can use a lighter red film with moderate light levels to trick them into thinking it is dark.

As Dakota said, ants do not rely on sight but in simple terms run of smells. (Hi Dekota, it's been a while xD) however to accurately answer your question. As long as the ants are at a considerable distance (to avoid their scent getting caught) in theory yes the ant would be semi invisible to any other ant (or fish) in their line of sight. However it is not a defensive mech just biology being beautiful yet again.