The Desert Locust is one of about a dozen species of short-horned grasshoppers (Acridoidea).  In response to environmental factors it can quickly form dense swarms of adults or bands of hoppers (young wingless locusts).

They have the ability to change their behaviour and habits, and can migrate over large distances.

During quiet periods, known as recessions, Desert Locusts are usually found only in the semi-arid and arid deserts of Africa, the Near East and South-West Asia that receive less than 200 mm of rain annually. This is an area of about 16 million km2, consisting of some 30 countries, ranging from Mauritania through the Sahara and Arabian Peninsula into western India.

When weather and habitat conditions are right for reproduction, multiple generations of locusts can be born and form swarms that invade countries that don’t usually have locust problems. This area can reach from the Mediterranean in the north to Nigeria and Tanzania in the south.

During plagues, the term for the worst level of locust infestation, Desert Locusts can spread over or into 60 countries and cover an area as large as 29 million km2  or 20 percent of Earth’s land surface. In plagues like these, the pest can pose a threat to the livelihoods of 10 percent of the world's population.

For more information on the extent of the 2020 Desert Locust upsurge that has affected East Africa, the Arabian Peninsula and Red Sea area, and Southwest Asia, see below.

Click here for up- to-date information on the global situation.

Desert Locusts can eat massive quantities of vegetation – wild plants, shrubs, trees and grass. These resources are critical for the health and survival of millions of pastoralist people in Africa, whose animals depend on them for forage. But also, food crops and fruit trees. The locusts, in effect, steal food from people's mouths and from the livestock they depend on to survive. This can badly erode the food security of communities and leave people stripped of household assets like seeds or animals. For more on locusts’ consumptive capacity, see below.

Locusts do not attack people or animals. There is no evidence to suggest that they carry diseases that could harm humans.

The swarms can be anything from under one km2 to several hundred km2. There can be from 40 million to 80 million adult locusts in each square kilometre of a swarm.

An adult Desert Locust can consume roughly its own weight, about 2 grams, in food every day. A 1 km2-sized swarm of 40 million Desert Locust could eat the same amount of food in one day as about 35 000 people. This is based on a person eating an average of 2.3 kg of food per day, according to the USDA.

To provide some perspective: A swarm the size of Paris could eat the same amount of food in one day as half the population of France; one the size of New York City could consume in one day the same as everyone in New York and California combined; one the size of Rome can eat the same amount of food as everybody in Kenya; one the size of Sydney (Australia), the same amount of food in one day as all of Australia eats in 1.5 hours.

Desert Locusts are polyphagous and feed on leaves, shoots, flowers, fruit, seeds, stems and bark. Nearly all crops and plants are on the menu, including maize, sorghum, barley, rice, sugarcane, cotton, fruit trees, vegetables, pasture grasses and weeds.

Desert Locusts can multiply 20-fold with each new generation every three months. That means that in half a year, a group of locusts can grow 400 times in number and within a year there can be 160 000 times as many as at the outset.

Desert Locust females lay eggs in an egg pod primarily in sandy soils at a depth of 10 to 15 centimetres below the surface. A solitary female lays about 95-158 eggs whereas a gregarious female lays usually less than 80 eggs in an egg pod. Females can lay at least three times in their lifetime, usually at intervals of about 6 to 11 days. Up to 1 000 egg pods have been found in one square metre.

Desert Locusts usually fly with the wind at a speed of about 16-19 km/h. Swarms take off about 2 hours after sunrise, fly during the day, and settle just before sunset. They can travel up to 130 to 150km or more in a day. Locusts can stay in the air for long periods. For example, locusts regularly cross the Red Sea -- a distance of 300 km.

As Desert Locusts increase in number and become more crowded, they change their behaviour from that of acting as an individual (solitarious) insect to that as acting as part of a group (gregarious). The appearance of the locust also changes: solitary adults are brown, whereas gregarious adults are pink (immature) and yellow (mature). Solitary Desert Locust adults usually fly at night, whereas gregarious adults (swarms) fly during the day. Up until 1921, it was thought that the Desert Locust was actually two different species for this reason.

At the moment, the situation in East Africa is not at plague level. It is an upsurge, which is one level before a plague . But it could become a plague if control operations are not adequate and weather favourable to breeding and further spread to other countries occurs.

Desert Locust infestations are identified in a sequence of increasing severity: recession (calm); outbreak; upsurge; plague (maximum intensity and scope). The rankings depend on the magnitude and geographical scale of the infestations.

An outbreak occurs when locusts rapidly increase in number and form groups, bands and swarms in an area of about 50 km by 50 km in one part of a country.

An upsurge usually occurs when locusts are able to breed uncontrolled for several successive seasons. This causes the formation of further hopper bands and adult swarms. This generally affects an entire region.

A plague is defined as a period of one or more years of widespread and heavy infestations, the majority of which occur as bands or swarms. A major plague exists when two or more regions are affected simultaneously.

The last time Somalia and Ethiopia saw an upsurge comparable to the current one (2020) was 25 years ago. Kenya and Uganda have not seen an upsurge at this scale for 75 years. Plagues tend to occur intermittently, rather than at specific intervals. Plagues of Locusts have been reported since Pharaonic times in ancient Egypt, but more recently in 1926-1934, 1940-1948, 1949-1963, 1967-1969 and 1986-1989.

Over the course of 2020 and 2021, the upsurge affected countries in East Africa, the Near East, and Southwest Asia. Precise estimates of the area of land that were or that remain infested are difficult to come by because the areas are vast, many are remote, and some are insecure and not easily surveyed. In addition, the swarms are constantly shifting from place to place

Since January 2020, millions of hectares of land have been surveyed in the countries covered by FAO’s East Africa and Yemen Desert Locust appeal since January 2020, and millions of hectares have been treated for infestations.

For the most up to date information, see the response dashboard as well as recent progress reports, here.

FAO operates a centralised Desert Locust information service to provide updates to all affected countries and give timely warnings and forecasts to those countries at risk of invasion. All locust-affected countries transmit data to FAO, which in turn analyses this information together with weather and habitat data and satellite imagery. FAO can then assess the ongoing locust situation, provide forecasts up to six weeks in advance, and issue ad-hoc warnings. Since 1978, FAO prepares monthly bulletins and periodic updates summarizing the situation, forecasting migration, and breeding on a country-by-country basis.

FAO also provides training, undertakes field assessment missions, and coordinates survey and control operations, as well as assistance during locust upsurges and plagues.

With over seven decades of experience in detecting, reporting and managing desert locust infestations, and five decades in preventing and responding to humanitarian emergencies, FAO has been working closely with affected countries, procuring materiel, providing crucial technical and coordination support.

Since January 2020, remarkable progress has been made to counter the upsurge.

Owing to strong capacities in Southwest Asia, the upsurge was contained and the situation there is now calm.

Scaled-up and sustained action in Eastern Africa has so far prevented a major humanitarian crisis and averted a further infestation in Western Africa. Over one million hectares of land have been surveyed and controlled in East Africa and Yemen, with over a half a trillion locusts killed. This aved 1.52 million tons of cereal from destruction.

For more, see FAO’s October 2020 progress report.

As of the first quarter of 2021, the most affected countries are Ethiopia, Kenya, Somalia, and Yemen.

Over the course of this upsurge that started in late 2019, a number of countries were affected, including: Djibouti, Eritrea, India, Iran, Kuwait, Nepal, Saudi Arabia, South Sudan, Sudan, Uganda and Tanzania. Western Africa was at one point at risk of invasion, but that invasion was averted.

Right now, the situation is calming and further spread of the upsurge seems unlikely. Click here for up- to-date information on the global situation.

Media accounts (during 2020) sometimes misreported the presence of Desert Locusts or confused Desert Locusts with other species. Sightings in Botswana, Namibia and South Africa have been of different species that do not present the same threat. Governments in these countries are capable of dealing with those other species. There is no Desert Locust risk to China, which lies outside the natural range of Desert Locust. China does experience Asian Migratory Locust swarms and is well equipped to deal with them.

Click here for up- to-date information on the global situation.

Media accounts (in early 2020) have sometimes misreported the presence of Desert Locusts or confused Desert Locusts with other species. Sightings in Botswana, Namibia and South Africa have been of different species that do not present the same threat. Governments in these countries are capable of dealing with those other species. There is no Desert Locust risk to China, which lies outside the natural range of Desert Locust. China does experience Asian Migratory Locust swarms and is well equipped to deal with them. Nepal did see a brief incursion of Desert Locust earlier this year, but locusts did not find optimal conditions there and moved back into India. As of August, there is no major threat in Nepal.

Also refer to “Which countries are being most affected by the current Desert Locust upsurge?” above, and click here for the latest information on the global situation.

Locust survey and control are primarily the responsibility of national Ministries of Agriculture in affected countries. There is a regional locust control organization in Eastern Africa that assists with aerial operations. During times of outbreaks and plagues, external assistance from the donor community and other international organizations like FAO is usually required.

FAO encourages only properly trained and equipped teams to undertake control operations against Desert Locusts, and not communities or farmers. FAO provides comprehensive training on all aspects of locust control. Whenever possible, FAO actively encourages countries to use biopesticide, especially in sensitive areas such as near water bodies, national parks, grazing areas with animals, and in habitations.

There are three types of commonly accepted standard practices in locust control:

• Conventional pesticides
• Biopesticides
• Insect growth regulators

At present the primary method of controlling Desert Locust swarms and hopper bands is with mainly organophosphate chemicals applied in small concentrated doses, referred to as ultra-low volume (ULV) formulation. This is done with vehicle-mounted and aerial sprayers and to a lesser extent by knapsack and hand-held sprayers. It is important to carry out effective control methods, such as spraying, early enough to curtail the surge in population.

Currently, 10 chemical pesticides (plus one biopesticide) have been recommended for use against Desert Locust by an FAO-convened body known as The Pesticide Referee Group. This is an independent body of experts that advises FAO on the efficacy and environmental impact of different pesticides in locust controls, based on current science. All uses of pesticides recommended for use by the Group are fully subject to national legislation, regulation and registration in the countries where they are used. 

There are alternatives to chemical pesticide that can be effective. When possible, FAO encourages countries to use them (see biopesticide, below).

Chemical pesticides used in locust control can pose risks to human and animal health.

None of the pesticides present major or long-lasting health risks to humans, unless exposure is severe – which is unlikely if proper measures are taken before, during, and after control campaigns.

The Ultra-Low Volume amounts (typically, one litre per hectare) used in the spraying are not likely to lead to causes of severe operator exposure.

None of the chemical pesticides being used in East Africa are harmful to crops. Some do pose low to medium risk to mammals, including domestic livestock and fish. Most present high risks to honeybees and other beneficial species.

Risks can be managed, using adequate precautionary measures and proper control measures.

The pesticides that governments are using in East Africa do break down in the environment, albeit at different rates of “biodegradation”.  Because they break down, these pesticides are not what are known as “persistent pollutants” that can build up in the environment and become concentrated in predators in the local food chain (bioamplification). 

See below for more on managing risks to humans, animals and the environment.

FAO and a range of partners working on Desert Locust management – including governments, and organization like the World Health Organization and the UN Environment Programme – have developed standard operating protocols to guide the planning and execution of control campaigns so that these responses are safe for human, animal and crop health.

Only substances that are legally registered and approved for locust control by national authorities are used. Governments typically adhere to internationally agreed standards when establishing their national rules. Banned pesticides are never used.

Thanks to precise targeting and close monitoring, control operation apply pesticides in the safest possible way. Spraying must be applied to the locust itself and not generally to vegetation. In the process, control officers carefully avoid inhabited areas, beehives and grazing animals. TO minimize negative environmental impacts blanket spraying is avoided.

Control team apply the minimum volume of pesticide possible and give as much attention to safety as to the control operation itself.

Only well-trained and properly equipped teams undertake control operations, not farmers.

Ground and aerial control operations always abide by appropriate precautions, including the use of protective clothing and masks and correct application protocols.

National, regional and local authorities inform communities in advance about control locations and what precautions they should take. At a minimum, livestock are moved out of areas marked for spraying until authorities say otherwise. Communities are advised to avoid going to treatment zones as spectators and to stay indoors if possible.

After the pesticide is applied, people and animals are not allowed to enter the area for a predetermined period of time. These so-called withholding periods are well-established by national authorities and communicated to communities.

As a precaution, people are warned not to eat treated locusts or animals that may have consumed them. Children are told never to touch dead locusts.

A partnership involving FAO, other UN agencies, and regional NGOs has prepared range of community information material in various local language on safety and best practices to support these efforts  (e.g., posters, radio announcements, booklets, text messages, etc.). These have been widely disseminated.

People in several countries collect locusts for food using large nets and other means. Locusts are usually stir-fried, roasted or boiled and eaten immediately or dried and eaten later. During periods of increased locust activity, piles of dead locusts can be found in the markets of many locust-affected countries and they are sometimes used as animal feed, too.

Locusts that have been killed by pesticides should under no circumstances be consumed, because they may still contain traces of pesticides.

In the context of the ongoing locust upsurge and the control campaign in East Africa, no one should eat any locusts, living or dead. Pesticide does not always kill the locusts immediately.

Even if these safety issues were not a factor, suggestions like catching locusts in nets as a potential source of food is not a realistic solution. One of the swarms spotted in Kenya in January 2020 covered an area of 40 km by 60 km (2400 square km.)

There are methods, but they are not the first tool of choice when swarms are of this magnitude. The best way to control the current upsurge in East Africa is through effective aerial and ground spraying of chemical pesticides – but biopesticides do have a role to play (learn more, here).

Extensive research is in progress on biological control and other means of non-chemical control of locusts. The current focus is primarily on pathogens and insect growth regulators. Thus far, control by natural predators and parasites is limited since locusts can quickly migrate away from most natural enemies. Although giant nets, flamethrowers, lasers and huge vacuums have been proposed in the past, these are viable options for locust control.

Bio-pesticides present an ecologically acceptable and safe, low-toxicity alternative to conventional pesticides in Desert Locust control. The active ingredient is a microorganism, an entomopathogenic fungus Metarhizium acridum. It triggers an epidemic disease among the treated insects.

When spores of the Metarhizium acridum fungus come into contact with the locust exoskeleton, they germinate on the cuticle and penetrate inside by pressure and enzymatic action. The fungus then multiplies inside the insect. The locusts are weakened and reduce feeding in three to four days, and die from seven days onwards. Under certain circumstances, the fungus can continue to produce spores in and on the dead locusts, which thus become a new source of contamination. Maximum mortality occurs two to three weeks after treatment. Both hoppers and adult locusts are susceptible to the bio-pesticide.

The viral Metarhizium acridum fungus is highly specific to locusts and grasshoppers. This means that it kills only these insects and does not negatively affect honeybees and other beneficial arthropods. It is not toxic to humans or animals such as birds, fish, reptiles, amphibians.

Due to the excellent ecotoxicological profile of Metarhizium acridum, it is a great fit for treating locusts in ecologically sensitive zones, such as nature reserves, wetlands or other areas with water bodies. The bio-pesticide is an appropriate tool for the preventive strategy to control the Desert Locust, particularly when it is necessary to treat initial, small groups of hoppers to prevent them from forming dense and huge hopper bands.

The bio-pesticide requires standard Personal Protective Equipment (usually, a face mask and long-sleeved shirt are sufficient) and can be applied with the same ULV spraying equipment as the chemical pesticides.

There are many reasons why it is difficult to successfully combat the Desert Locust. Some of these are:

1. the extremely large area (16 - 30 million km2) within which locusts can be found;
2. the remoteness and difficult access of such areas;
3. the insecurity or lack of safety (such as land mines) in some areas;
4. the limited resources for Locust monitoring and control in some of the affected countries;
5. the undeveloped basic infrastructure (roads, communications, water and food) in many countries;
6. the difficulty in maintaining a sufficient number of trained staff and functioning resources during the long periods of recession in which there is little or no locust activity;
7. political relations among affected countries;
8. the difficulty in organizing and implementing control operations in which the pesticide must be applied directly onto the Locusts;
9. the difficulty in predicting outbreaks given their lack of periodicity and the uncertainty of rainfall in Locust areas; and
10. the lack of reliable forecasts and advanced warning of cyclone and other severe weather that often trigger to Desert Locust outbreaks and upsurges.

Satellites used to monitor the weather and environment cannot detect individual locusts or swarms. Highly sophisticated satellites used by the military can, but these images are not available for civilian use. (And it is unlikely that national and international locust organizations would be able to interpret the hundreds of images that such satellites would produce daily).

Still, satellites play an important role in locust forecasting and control> this is because they provide data on weather, ground cover and soil moisture that help scientists and governments identify areas where locusts might go to lay their eggs, find food and shelter. This information can then be used to guide survey and control operations.

Dedicated locust teams, supplemented by additional field staff, use one of the eLocust3 tools developed by FAO to record their observations while in the field during survey and control operations: eLocust3 (a rugged tablet connected to a satellite antenna), eLocust3g (a handheld GPS satellite communicator), eLocust3m (a mobile app) or eLocust3w (a web form). The data are sent in real or near-real time to the country’s national locust centre where it is validated and sent to the Desert Locust Information Service at FAO Headquarters. From there, the data are made available to public on the Locust Hub (https://locust-hub-hqfao.hub.arcgis.com). These data are the foundation for the global Desert Locust early warning system and are used for planning and implementing control operations in affected countries and for analysis and forecasting by FAO.

FAO is researching and developing both rotary and fixed-wing drone solutions for surveys and – potentially – treatment. Typical commercial drones are not likely to be robust or useful enough for long-distance locust operations. Therefore, FAO is testing purpose-built fixed-wing drones for long-distance surveys of up to about 100 km. They can collect data on the location of green vegetation and process this imagery as a map. Camera-equipped rotary drones are also in development to map vegetation in hard-to-reach sites and with their ability to hover in place, they offer control teams the option to identify locust concentrations from the air. FAO is also testing ways to use rotary drones for small, targeted spray operations. For more information, click here.

No. Early warning and prevention works best in frontline countries. The East African countries currently affected by Desert Locusts do not belong to this category, meaning they don’t usually experience locust outbreaks. The situation in East Africa is the result of a series of extraordinary and severe weather events, which made the outbreak and upsurge unpreventable. This includes two cyclones in a remote part of the Arabian Peninsula in 2018 that enabled locust to breed freely and for multiple generations to be born. This was followed by severe rains in Yemen, Iran, and on the India-Pakistan where locusts usually travel. Finally, just when weather was drying out, the Horn of Africa experienced a cyclone in December 2019, which allowed locusts to stay and breed two generations. This tipped the scale into an upsurge.

When the populations and swarms of locusts are as large as they are right now in East Africa, large-scale application of pesticide by aerial and ground crews is simply the only way to get their numbers under control.

FAO had to overcome some supply chain challenges in the early days of COVID-19 but is now focusing on training control officers in new ways and adapting anti-locust operations to the new operational context:

To avoid operational delays, FAO, diversified the sources of its control products in the early days of COVID-19. This meant prioritizing batch deliveries over bulk procurements to spread risk across the supply chain.

Trainings have also been adjusted. FAO is now delivering many trainings remotely and using video tools for situations where group gatherings are not permitted. Some in-person classes, such as locust scout training, have been decreased in size and the frequency of sessions increased. 

Finally, some governments have imposed curfews that reduce the number of hours that the teams can operate. Still, control operations continue, with additional health and safety protocols in place. Most FAO experts deployed to help locust affected countries were already in place before COVID-related restrictions came into effect. FAO and governments are focusing on sourcing expertise and manpower from within affected countries and help governments build national and local capacities.

Importantly, regardless of the demands of COVID-19, the international community has not disengaged.