They normally get browner as they get nearer emerging as an adult ant, they are black ants afterall? They are "born" pale yes but the colour change begins while they are pupae/cocoons. So do not worry this is normal

Formica larvae need to be buried to spin a cocoon (like any cocoon spinning ant), one Queen obviously found a way to do this in the test tube, most likely by pulling cotton wool, the other obviously didn't so her larvae just became pupae. Again normal and nothing to worry about.