While the rest of the world watches the coronavirus spread into many countries, one section of the globe is facing another catastrophe. Locusts, billions of them. In fact the biggest swarms of locusts seen for decades has begun to decimate the food supply in parts of East Africa, deepening the already severe hunger crisis.

Crops in Kenya, Somalia, and Ethiopia have been decimated by swarms of billions of locusts, the likes of which hasn’t been seen for more than 25 years. One swarm measured 37 miles long by 25 miles wide in Kenya’s northeast, the Intergovernmental Authority on Development said in a statement.

The swarms of locusts were described as “a scourge of biblical proportions” and “a graphic and shocking reminder of this region’s vulnerability,” according to U.N. officials Qu Dongyu, Mark Lowcock, and David Beasley.

Keith Cressman, the U.N. Food and Agriculture Organization’s (FAO) senior locust forecasting officer, said Kenya has received “waves and waves of swarms” since the beginning of the year from the Horn of Africa, and “over the weekend they moved on the side of Mount Kilimanjaro across the border into Tanzania.”

Now the hordes have appeared in Uganda, with the U.N. sending out a warning the fragile region “simply cannot afford another major shock.”

“Also over the weekend, they moved into northeastern Uganda,” he told a news conference at U.N. headquarters in New York. “We’re expecting any day they will move across the border into the southeast corner of South Sudan.”

Cressman warned that immediate action is needed, before more rains fall to feed the new generations of locusts, “that swarm in one day can eat the same amount of food as everybody here in the tristate area, New Jersey, Pennsylvania, and New York. So not taking action in time—you can see the consequences.”

“There is the risk of a catastrophe,” U.N. humanitarian chief Mark Lowcock told a briefing in New York on Monday, as with 13 million people already facing severe food shortages, 10 million of those are living in areas decimated by the locusts.