At least six African countries have been affected by what has been described as one of the continent's worst locust outbreaks in decades. Somalia has declared the outbreak a national emergency while Kenya, Sudan, Ethiopia, Eritrea and Djibouti have all been affected. The locusts - part of the grasshopper family - have led to what the Food and Agriculture Organization (FAO) has termed the "worst situation in 25 years" in the Horn of Africa. Social media users have captured footage of the outbreak, showing just small parts of what is believed to be billions of locusts flying across the region, causing devastation to food crops that could lead to a spike in hunger in an area of the world where millions are already food insecure. One showed a "locust invasion" in Kenya. Another Twitter user showed a swarm scaring children in Garissa, a city in eastern Kenya. A Kenyan resident uploaded footage that showed the sky darkened by countless locusts, saying that it had turned "black" when they began flying and that those caught in it were "being hit on all sides". Authorities are trying to battle the swarm by spraying pesticides over them to kill large numbers off, but they are flying large distances every day and now threaten other countries, such as Uganda, South Sudan and Tanzania.