This is one of planet Earth's greatest spectacles. 这是地球上最壮观的景象之一

323. swarms join up with other swarms
     一团蝗虫云也会和其它蝗虫云汇合
324. to form gigantic plagues several billions strong and as much as 40 miles wide.
     从而形成巨大的灾害 无数“瘟神”组成的大军绵延长达40英里
325. They will consume every edible thing that lies in their path.
     它们将把一路上能吃的东西 全部吃得精光
326. This is one of planet Earth's greatest spectacles.
     这是地球上最壮观的景象之一
327. It's rarely seen on this scale
     很少能看见如此大的规模
328. and it won't last long.
     而且也不会持续多久
329. Once the food is gone,
     待到食物耗尽之时

来自《行星地球 第一季 第五集 Planet Earth S01E05 沙漠》第 326 行