The desert locust has been described by Food and Agriculture Organization as one of the most destructive pest in the world. The breed has capability of going from a solitarious form to gregarious form, hence developing characteristics of group behavior and acting in unison, a process referred to gregarisation. This is triggered by physical contact and inclination to disperse together and find food.
Desert locust invasions are not new. They have been recurring in different periods, in different parts of the world since 1860. The periods include:1860-1867, 1869-1881,1888-1910, 1912-1919, 1926-1935, 1940-1947, 1949-1962 and 1987-1989. The last invasions were  followed by local upsurges in 1992 to1994 and 1997 to1998, and the recent one we are facing. The current invasion originated from the Arabian Peninsula during 2018-2019, resulting to three generations of breed that was unnoticed and not controlled. This resulted in the swarm spreading from middle eastern countries to the Horn of Africa.
A one km² size swarm caries roughly 40 million locusts, that can consume in a day food equivalent to that of 35,000 people, 20 camels or 6 elephants. Also, a mature one can feed its own weight in fresh food a day, which on average is two grams per day. The desert locust can survive and spread due to its ability to adapt to different environmental conditions and change to be part of other harmless insects. Together they form a swarm that move from continents and seas causing destruction.
Desert locusts in Eastern African countries and the Horn of Africa is a threat to food security. It is estimated that the locusts have caused great damage to the neighboring countries such as Ethiopia and Somali. On average, 110,000 hectares in the Horn of Africa have been affected by the latest locust invasion, with 70,000 and 65,000 hectares of crops having been destroyed in Somali and Ethiopia, respectively.
Kenya Situation Analysis
Kenya experienced the desert locust invasion since 28 December 2019 which, according to FAO, is the worst invasion in seventy years. The locusts invaded the country through Somalia and Ethiopia borders, using the Wajir and El Wak routes. As of February 2020, they had spread to counties such as Mandera, Marsabit, Garissa, Samburu, Laikipia, Machakos, Turkana, Tharaka Nithi, Tana River, Wajir, Isiolo, Meru, Embu, Kitui, and Baringo with spread to other counties expected to increase.
Figure 1: The movement of locusts in Kenya
Figure 2: A resident of Taiboto in Isiolo County warding off desert locusts (January 11, 2020)
Source: Nation Media Group
The locusts spread has been attributed to different factors, among them the change in climate due to global warming, according to Food and Agriculture Organization. Cyclones in May 2018 in the Southern Arabian Pensula caused heavy rainfall which provided a conducive environment for locust breeding in Yemen. Since there was no sufficient mechanism to control the locusts, this allowed the spread of the three generations of breeding to migrate through Saudi Arabia, Iran and to the Horn of Africa before invading Kenya.
The locusts are also able to breed faster within a short life. It takes approximately two weeks for the locusts to reach sexual maturity. Adult locusts usually group into swarms of thousands. Inadequate finances to control the spread, and poor disaster preparation is another factor that has greatly contributed to the spread of the pests. This has resulted in the government being overwhelmed by the vastness and inaccessibility of the areas affected by the pests.
A coordinated approach using various measures can be applied, whether small or large scale, to control the spread of the desert locusts in the country. Individual farmers can take the initiative of preparing the pesticides in advance which they can spray once pests hit their farms. Therefore, given that the swarm moves at high speed, it would be good to pre-empty any attempt to spread further at any given time. Spraying chemicals mainly organ-phosphate over the farm, either using a tractor sprayer or a plane, will buy valuable time. Natural predators and parasites control has limitation considering that the they can quickly move away from natural enemies. Birds and some communities eat the locusts; however, this method is not effective in reducing the spread of locusts over large areas. The other way of controlling the spread is by early monitoring mapping and destroying the hatching sites. This is possible since their movements can be tracked using GPS radio.
It is important that the Government increases surveillance and mapping of the locust spread guided by weather forecast and likelihood of locust invasion outbreak by using the latest technology such as GPS and drones in tracking their movement.
By: Bonface Munene and Simeon Tunje
 Michel Lecoq – Desert Locust Threat to Agricultural Development and Food Security and FAO/International Role in its Control