What you should know about desert locusts and how to handle them

Tuesday January 14 2020

The desert locust, scientifically known as Schistocerca gregaria (Forskal), is a highly destructive agricultural pest across the globe. 


The swarms of desert locusts in Kenya are likely to have come from Somalia through Mandera and El Wak in December 2019. The swarms that entered the country were adult but immature, meaning, they were not ready to mate and lay eggs. But this could soon change.

While locusts and grasshoppers belong to the same group of insects called Acredidae, or the short-horned grasshoppers, they have significant differences. Grasshoppers have only one life form, while locusts have two distinct forms under natural conditions. Also, grasshoppers do not swarm or fly long distances.

Locusts can either lead a solitary life or a gregarious one. Solitary life is in areas of its known breeding sites and natural occurrence. During this phase, their population is low and, therefore, they do not pose a risk to agricultural or pasture land. They are usually brown in this phase. 



It’s in the gregarious phase that the locusts band to form swarms that can be devastating to crops and pasture. In this phase, the morphology, behaviour and life cycle change. 

The locusts enter the gregarious phase if there is sufficient rainfall that guarantees enough vegetation for the young ones, and the ground is moist for egg development. The insects then breed and grow their numbers. With the population being high, they change their behaviour and aggregate, eating and moving together en masse. 

The gregarious desert locust adults are pink in colour when not yet ready to mate and lay eggs (immature) but turn yellow when mature. 

To prevent them from progressing to the gregarious phase, measures are taken to reduce their numbers. This is why continuous monitoring is paramount. 


The life cycle of the locust consists of eggs, nymphs and adult. The eggs take about two weeks during favourable conditions to hatch into nymphs. Both nymphs and adults are feeders. 

However, the nymphs (also known as hoppers) do not have wings and become adults 30-40 days after hatching. 

The young adults take about three weeks before they are ready to mate and lay eggs. Adults live for three to five months.

Locust swarms can fly at a speed of more than 15km/h and can cover a distance of more than 100km a day, staying in the air as long as there is no green vegetation sighted. These swarms can be as large as 80 million individuals. Swarming occurs during the day. 

Since the insects prefer warm-hot areas, it’s expected that cold areas will not be affected.


The insects are not native to Kenya and, therefore, do not have breeding grounds in the country. However, Kenya’s neighbours, such as Ethiopia and Eritrea, have breeding grounds, which pose a threat. 

It is for this reason that Kenya is a member of the Desert Locust Control Organisation, which helps to monitor and advise the countries on locusts. 

It also helps in managing the breeding areas. The last locust plague in Kenya was in the 1970s. 

The following are some of the dos and don’ts when it comes to dealing with the locust problem. 

Considering their flight capability, it is advisable to report as quickly as possible any sighting of a swarm to the nearest county officer or national government officer, or place images in social groups. This will allow the government to respond in good time. 


The public is discouraged from sending old images or those copied from websites and passing them off as recent. This chase for “likes” may have devastating consequences. Control of the pests is highly dependent on correct reporting. 

Chemical control should be managed centrally; there’s no need for an individual farmer to use such means as it may not work. 

Making loud noises scares away the locusts and increases the rate at which they spread.

Unsprayed swarms can be a good source of food for humans and animals. Locusts have high protein content and unique nutritive elements. Innovative companies that make animal feeds would do well to harvest them as a cheap protein source.


Kenya has a number of advantages that will make it possible to successfully manage the plague: relative peace and roads to allow access to the swarms, good Internet and communication infrastructure that allows quick updates on incidents, and supportive institutions. 

Dr Kasina is the chairman, Entomological Society of Kenya.​