East Africa is currently dealing with giant swarms of locusts, which will descend on an area and eat huge amounts of vegetation before moving on to the next. This poses an enormous risk to subsistence farmers in the region, only partially mitigated by the fact that it’s the dry season and the main crops aren’t growing yet. According to Cyril Piou at The Conversation,
As a rough estimate, a swarm of one billion insects covers approximately 20km² and will eat 2000 metric tons of vegetation each day. In the past few weeks, parts of Kenya have received swarms that cover more than 100km², so their feeding will have been devastating.
Where are the locusts coming from?
The current invasion of desert locust originated along the Red Sea, in Yemen and Oman, during the 2018 to 2019 winter. The rains, brought by the October 2018 cyclone Luban, produced areas full of vegetation where the locusts could feed, breed and [seek additional food].
From January 2019, small swarms spread in the Arab Peninsula, along the Red Sea and even reached Iran and Pakistan. Other swarms stayed in the Arab Peninsula where they reproduced and multiplied.
In June, the locusts crossed the Red Sea or the Gulf of Aden, which is just a few hours of flight for the locusts, and started to spread into the Horn of Africa. They invaded the North of Somalia and Ethiopia where floods in October and November created good conditions for desert locust to continue to multiply. The large swarms that have invaded Kenya since December are a result of this.
It’s possible to use ground surveys and satellite data to find the locusts when they’re young, before they start swarming, and kill them with targeted applications of pesticides. Once they’ve begun to swarm, the only control option is spraying pesticides across the entire affected area, which is much worse for the ecosystem.
This is ultimately a crisis of state capacity. Yemen and Somalia are particularly poorly placed to undertake preventative work. Northern Kenya receives a small fraction of state funding compared to the central regions, and the government’s response to the 2019 drought and famine in the region was slow and entirely lacking in transparency. There’s not much reason to hope for a more proactive response to locusts.