Is anything required of me for killing locusts in the Haram of Makkah after performing Umrah, knowing that I was unaware of its prohibition?

The preponderant view among scholars is that it is forbidden to kill locusts in the Haram area for both those in and out of the state of ihram. Whoever does so must pay a penalty, which is the value of what they killed. It is also said that for every locust killed, one should give a date in charity. Locusts are considered land game, and thus compensation is due for them, because they are land birds, similar to sparrows in their value in that place. Hunting in the Haram is forbidden for both those in and out of the state of ihram, by textual evidence and consensus.

Therefore, you must give charity equivalent to the value of the locusts you destroyed. If you do not know their number, you must err on the side of caution, because one's obligation is not discharged except by certainty.