As locusts devour crops in Ethiopia, Kenya and Somalia, the insects are breeding in Djibouti, Eritrea and Sudan—all areas that are prone to drought and food shortages. Swarms have now arrived in Uganda, and locusts have also crossed into Tanzania.

The number of locusts in East Africa could expand 500 times by June, the UN’s Food & Agriculture Organization said last month. The region gets heavy seasonal rains—and great locust-breeding and swarming conditions—from March through May. Last year, the October-to-December rainy season was among the wettest in 40 years, with cumulative rainfall ranging from 120% to 400% of normal.

“Locust outbreaks are expected to become more frequent and severe under climate change,” said Rick Overson, a research coordinator at the Global Locust Initiative at Arizona State University. “Locusts are quite adept at responding rapidly and capitalizing on extreme rainfall events.”