How to make particles that appear at night fade in?

Hello people. I have a question that might be easy but maybe I’m just overlooking something to solve it. See I have this firefly particle effect that appears at night time but when it appears it does so in an abrupt manner. Tried using timelines to make a fade in and fade out effect but I haven’t managed to make it work.

Is there a particular way to achieve a fade in, fade out effect on particle blueprints?

Thanks

You want colour over life or alpha over life if your material is using particle colour alpha.