In pictures: Locust swarm threatens food security in Horn of Africa

A farmer attempts to fend off desert locusts as they fly in his khat farm on the outskirt of Jijiga in Somali region, Ethiopia. Swarms of desert locusts have spread from Ethiopia and Somalia into eastern and northern Kenya, posing a threat to food production and grazing land.

Locust feed of a plant near the village of Riandira in Kirinyaga County, Kenya. The locusts - part of the grasshopper family - have led to what the Food and Agriculture Organisation (FAO) has termed the "worst situation in 25 years" in the Horn of Africa.

A girl attempts to fend off desert locusts as they fly in a farm on the outskirt of Jijiga in Somali region, Ethiopia. Desert locusts - whose destructive infestations cause major crop damage and hunger - are a species of grasshopper that live largely solitary lives until a combination of conditions promote breeding and lead them to form massive swarms.

Locust feed of a plant near the village of Riandira in Kirinyaga County, Kenya. According to the FAO, swarms can travel up to 130km per day - a kilometre-wide swarm can contain up to 80 million locusts.

A desert locust is seen feeding on a plantation in a grazing land on the outskirt of Dusamareb in Galmudug region, Somalia. Swarms formed in eastern Ethiopia and northern Somalia and have moved through the region, possibly still threatening South Sudan and Uganda.

Desert locusts are seen in a grazing land on the outskirt of Dusamareb in Galmudug region, Somalia. The United Nations agricultural organisation in December said some 70,000 hectares (173,000 acres) of land had been infested in Ethiopia and Somalia.

Locust feed of a plant near the village of Riandira in Kirinyaga County, Kenya

A man sprays organic pesticide on locusts to demonstrate its effects in fighting their spreading, near the village of Riandira in Kirinyaga County, Kenya

An Ethiopian farmer, attempts to fend off desert locusts as they fly in his khat farm on the outskirts of Jijiga in Somali region, Ethiopia

Locust feed of a plant near the village of Riandira in Kirinyaga County, Kenya

A motorist drives within desert locusts near a grazing land on the outskirt of Dusamareb in Galmudug region, Somalia

Locust feed of a plant near the village of Riandira in Kirinyaga County, Kenya

A boy attempts to fend off desert locusts as they fly in a farm on the outskirt of Jijiga in Somali region, Ethiopia

Ahmed Ibrahim, 30, an Ethiopian farmer attempts to fend off desert locusts as they fly in his khat farm on the outskirt of Jijiga in Somali region, Ethiopia

A girl attempts to fend off desert locusts as they fly in a farm on the outskirts of Jijiga in Somali region, Ethiopia