I completely agree. Since you mentioned finding them near the road, you might want to feed the queens that haven't layed eggs some protein.
What might have happened is that they were underfed as larvae due to lack of resources since part of their foraging area was a dead, barren road. This might make it harder for them to lay eggs. By feeding them some protein, it partially compensate for this.
Just a thought, may or may not work .
ok, I will try that, It won't hurt them i don't think