unusually heavy rains that stretched from Dakar, Senegal, to Morocco in October allowed breeding conditions to remain favourable for the next 6 months and the desert locusts rapidly increased. Lack of rain and cold temperatures in the winter breeding area of northwest Africa in early 2005 slowed the development of the locusts and allowed the locust control agencies to stop the cycle. During the upsurge, nearly were treated by ground and aerial operations in 23 countries. The costs of fighting this upsurge have been estimated by the FAO to have exceeded US$400 million, and harvest losses were valued at up to US$2.5 billion, which had disastrous effects on food security in West Africa. The countries affected by the 2004-2005 upsurge were Algeria, Burkina Faso, the Canary Islands, Cape Verde, Chad, Egypt, Ethiopia, the Gambia, Greece, Guinea, Guinea Bissau, Israel, Jordan, Lebanon, Libyan Arab Jamahiriya, Mali, Mauritania, Morocco, Niger, Saudi Arabia, Senegal, Sudan, Syria, and Tunisia. 2019–2021 desert locust upsurge In May 2018, Cyclone Mekunu brought unprecedented rainfall to the Empty Quarter of the Arabian Peninsula that was followed by Cyclone Luban that brought heavy rains again to the same area in October. This allowed conditions to be favourable for three generations of breeding, which caused an estimated 8,000-fold increase in Desert Locust numbers that went unchecked because the area was so remote it could not be accessed by national locust teams. In early 2019, waves of swarms migrated from this remote and inaccessible area north to the interior of Saudi Arabia and southern Iran, and southwest to the interior of Yemen. Both areas received good rains, including heavy flooding in southwest Iran (the worst in 50 years), that allowed another two generations of breeding to take place. While control operations were mounted against the northern movement and subsequent breeding, very little could be done in Yemen due to the ongoing conflict. As a result, new swarms formed that crossed the southern Red Sea and the Gulf of Aden and invaded the Horn of Africa, specifically northeast Ethiopia and northern Somalia in June 2019. Again, good rains allowed further breeding during the summer, followed by another generation of widespread breeding during the autumn in eastern Ethiopia and central Somalia, which was exacerbated by the unusually late occurring Cyclone Pawan in northeast Somalia in early December. The swarms that subsequently formed invaded Kenya in late December 2019 and spread throughout the country