Desert Locust: Current upsurge (2019–2021), 29 November 2021
2018
● Cyclones in May and October brought heavy rains that gave rise to favourable breeding conditions in the Empty Quarter of the southern Arabian Peninsula for at least nine months since June.
● As a result, three generations of breeding occurred that was undetected and not controlled.
2019
● JANUARY: the first swarms left the Empty Quarter to Yemen and Saudi Arabia, reaching southwest Iran where heavy rains fell.
● FEBRUARY-JUNE: widespread spring breeding in Yemen, Saudi Arabia and Iran caused large numbers of swarms to form. Control operations were less successful in Iran and Yemen.
● JUNE-DECEMBER: swarms invade the Indo-Pakistan border from Iran and up to three generations occur due to longer than normal monsoon, giving rise to large numbers of swarms; In Yemen, swarms form and move to N Somalia and Ethiopia where breeding occurs and more swarms form.
● OCTOBER-DECEMBER: Swarms move from Ethiopia and N Somalia to Eritrea, Djibouti, E Ethiopia, the Ogaden, C and S Somalia to reach NE Kenya; hopper bands and swarms form along parts of the Red Sea coastal plains in Yemen, Saudi Arabia, Eritrea and Sudan.
2020
● JANUARY: Swarms continue to invade, spread, mature and lay eggs in Ethiopia and Kenya. Hatching occurs in NE Somalia. Other swarms move into interior of Yemen and Saudi Arabia.
● FEBRUARY: Swarms continue in Kenya, a few reach Uganda and South Sudan, groups reach Tanzania. Widespread hatching and bands in Kenya. Other swarms reach both sides of Persian Gulf.
● MARCH: widespread hatching causes a new generation of swarms to form in Ethiopia and Kenya. A few swarms invade Uganda and South Sudan. Widespread swarm laying and hatching in southern Iran.
● APRIL: More swarms form, mature and lay eggs in Ethiopia, Kenya, Somalia, and Yemen. Second-generation hopper bands form in Iran and Pakistan.
● MAY: Another generation of hatching and band formation in Ethiopia, Kenya, Somalia, and Yemen. Second-generation swarms form in Iran and Pakistan, and migrate to Indo-Pakistan, continuing to northern India.
● JUNE: Second-generation swarms form in NW Kenya and swarms form in Ethiopia, Somalia, and Yemen. Spring-bred swarms continue to move to Rajasthan and northern states of India.
● JULY: More swarms form in NW Kenya, Ethiopia, Somalia, and Yemen. Some swarms move N to Ethiopia, other swarms move from Yemen to NE Ethiopia. First-generation laying, hatching and band formation occurs along Indo-Pakistan border.
● AUGUST: Swarms mature and lay in NE Ethiopia, some swarms invade Eritrea and breed; immature swarms persist in NW Kenya and N Somalia; bands and swarms continue in Yemen interior, some swarms move to SW Saudi Arabia.
● SEPTEMBER: Widespread hatching and band formation in NE Ethiopia and Yemen, immature swarms persist in N Somalia, N Kenya. Swarms arrive in E Sudan and lay. SW Asia returns to calm.
● OCTOBER: Numerous swarms form in Ethiopia and move E; swarms mature and lay in NE Somalia and move S; breeding declines in Yemen interior but bands and swarms form on Red Sea coast; bands form in E Sudan, Eritrea, Saudi Arabia.
● NOVEMBER: Widespread breeding in E Ethiopia and C Somalia cause bands and swarms; cyclone Gati in NE Somalia allow extension of breeding to N; Red Sea coast breeding with bands and swarms in Sudan, Eritrea, Saudi Arabia.
● DECEMBER: More swarms form in E Ethiopia and C Somalia that move to S Ethiopia and NE Kenya (21 December); breeding in N Somalia and Red Sea coast continues.
2021
● JANUARY: Numerous swarms continue to invade S Ethiopia and N+C Kenya and a few to NE Tanzania; swarms move to NE Ethiopia and Eritrea; swarms move from Yemen to Saudi Arabia; more breeding in N Somalia and Red Sea coast, primarily Saudi Arabia.
● FEBRUARY: Swarms remain immature and decline in Kenya and Ethiopia; a few swarms in NE Tanzania; more swarms form in N Somalia; swarms form on Saudi Arabia Red Sea coast and move inland to spring breeding areas and lay.
● MARCH: Swarms continue to decline due to control operations and poor rains in the Horn of Africa as upsurge eases; laying, hatching and band formation in Saudi Arabia interior; a few swarms migrate to SW Iran via Kuwait.
● APRIL: Swarms end in Kenya but rains in Ethiopia and NW Somalia all swarms to mature; mature groups & swarmlets move N from Saudi Arabia to Iraq, Jordan, Syria, Lebanon, Israel and Sinai (Egypt).
● MAY: Hatching and bands form in E Ethiopia and N Somalia; immature adult groups form in C Saudi Arabia and a few move S; local hatching and few bands in Iraq, Jordan, Lebanon, Syria.
● JUNE: Swarms start to form at mid-month in NW Somalia and some in E Ethiopia and Djibouti; a few swarms from N Saudi Arabia reach N Yemen.
● JULY: Limited swarms arrive in NE Ethiopia with good rains; swarms decline in NW Somalia.
● AUGUST: Breeding likely in NE Ethiopia but conflict prevents operations; remnant swarms in N Somalia; breeding and few bands in Yemen.
● SEPTEMBER: Hopper bands and immature swarms form in Afar, SE Tigray, E Amhara but surveys and control not possible due to conflict; few spring-bred swarms persist in N Somalia; new swarms form in Yemen interior.
● OCTOBER: Few small mature groups and swarms from N Ethiopia move to Eritrea coast and lay; hatching and bands form in NE Somalia; small-scale breeding with few hopper bands on coast in S Yemen; summer-bred hoppers and adult form groups in N Sudan.
Source: Food and Agriculture Organization of the United Nations