Locust swarms were seen to have emerged in many places of Rajasthan & Uttar Pradesh. But what are these locust swarms? Have they caused damage earlier in India? Here is a detailed explainer. Over the past few days there are reports of emergence of swarms of locusts in India, especially in different places of Rajasthan, Uttar Pradesh, with possible spread to Gujarat and other states. With the country already reeling due to the impact of COVID-19 and the lockdown, the potential damage that can be caused by locust swarms has added to the apprehension and panic among public. However, the emergence of locust swarms is not a new phenomenon and India has a history of regular occurrence of the locusts. In this story we take a look at the type of locusts, their emergence and distribution, economic impact and other details relating to the locusts. Desert Locust is one of the four species found in India The locust swarms that are currently being reported in India belong to the species of Desert Locust (Scientific Name: Schistocerca gregaria). Locusts are short-horned grasshoppers whose behaviour includes : In certain circumstances, the locusts are capable of forming swarms i.e. congregation of adults as well as hopper bands (congregation of nymphs/immature insects). This ability to form large swarms and migrate at rapid rates over large areas along with their gregarious feeding habit makes them a threat to crops and other vegetation. There are 10 important species of locusts, whose details are below. Out of these, four species are found in India – Desert Locust, Migratory Locust, Bombay Locust & Tree Locust. Desert locusts in gregarious condition form Swarms. As highlighted earlier, locusts are a type of grasshoppers. The life cycle of Locusts consists of three stages : (1) Eggs (2) Hopper (3) Adult. The eggs are laid in pods in moist sandy soil at a depth of 10 cm. The rate of development of eggs depends on soil moisture and temperature. The incubation period is 10-12 days with an optimum temperature between 32-35 °C. No development of egg takes place below 15°C. In most cases, these grasshoppers are solitary creatures. However, certain circumstances like scarcity of food or drought conditions drive them to form groups. Once the population of the group increases, they tend to become gregarious i.e. tendency to form large groups to hunt or eat together. As per experts, Locusts tend to become gregarious when they constantly touch each other on the hind legs and release a chemical called serotonin. These gregarious locusts start co-ordinating their movements and form swarms. There are three forms of swarms identified : There are marked changes observed in the locusts in terms of their behaviour as well as their appearance, once they enter this gregarious phase. As per UN’s Food and Agriculture Organization (FAO), locusts have the ability to multiply nearly 20-fold in span of 3 months when the conditions become favourable, like good rains. In general, there are three breeding seasons for locusts: India has only one breeding season i.e. Summer breeding, meanwhile Pakistan has both spring and summer. Desert Locusts are transboundary pests ranging from Northwest Africa to Indian Subcontinent As per government information, parts of around 64 countries come under the area covered by desert locusts i.e. around 30 million sq. kms. The Geographical extent includes: They inhabit a broad range belt of Arid and Semi-arid region from Atlantic Ocean to North West India, during their quiet period. The Scheduled Desert Area in India encompasses 16 districts across the states of Rajasthan, Gujarat and Haryana. This covers a total area of around 2.05 lakh sq. kms. Current Locust Swarming has its origins in East Africa The size of the locust swarms being seen in India currently are larger compared to recent years. The locusts generally arrive in India during their Summer breeding season i.e. July-October. The current swarm of locusts entering India is attributed to the spate of heavy cyclones and rainfall over the past two years due to climate change. The arid regions of Arabian Peninsula and East Africa are among the typical regions where the desert locusts reside. The Horn of Africa region experienced heavy rains in 2018, which followed a phase of severe drought in previous years. This resulted in severe floods in countries like Kenya, Somalia and Ethiopia. The resultant wet climate created conditions favourable for breeding of the locust. Even the hitherto, dormant eggs were re-awakened, and this has resulted in near 8,000-fold increase in the locust numbers and reaching swarm levels by early 2019. These then moved to Iran, Yemen, Saudi Arabia and into Pakistan. Here, newer swarms were formed. Eventually they landed in India.