Albert's Swarm
en.wikipedia.org
en.wikipedia.org
Turns out this species - the Rocky Mountain locust was made accidentally extinct by settlers. Although the swarms could be huge, they had a small and concentrated breeding ground that was destroyed by farming and cows. Wikipedia says the last specimen was collected in 1904.
>The locusts not only ate the grass and valuable crops, but also leather, wood, sheep's wool, and—in extreme cases—even clothes off peoples' backs
https://en.wikipedia.org/wiki/Rocky_Mountain_locust#Last_maj...
What if a mad scientist would do that? :)
UPD Found a reddit discussion on the topic: https://old.reddit.com/r/megafaunarewilding/comments/17gxmux...