Locusts are invertebrates from swarm groups. The scientific name of locusts is Acrididae. They survive on a herbivores diet. Locusts migrate in swarms, with a speed of 16 to 19 km/hr depending on the wind speed. They can migrate thousands of kilometres within a week. In 1954, locusts migration from North-West Africa to the British Isles was recorded, as well as in 1988, they migrated over 5000 km within 10 days from West Africa to the Caribbean.
Life Cycle of Locusts:
They are paper pin-sized and have a life of several months. In this period female locusts can lay 80-158 eggs with the interval of 6-11 days. Solitary females may lay 95-158 eggs whereas, gregorian females can lay up to 80 eggs in one pod. There have been 1000 such pods found only in one square kilometre of area, one can imagine the speed of multiplication of locust population in a short period of time. Thus, the multiplication of locusts is a very fast process.
There are three stages of locusts life, 10-65 days in the egg, 24-95 days as a non-flying nymph that is hopper, and 2.5 to 5 months as an adult. Locusts can be solitary or gregarious depending on the environmental conditions. Locusts can change their behaviour as well as appearance. Generally having a solitary lifestyle, once the favourable environmental conditions start production of locusts rapidly, they change their behaviour to gregarious by staying in the locust crowd.
Migration of Locusts:
Locusts occur generally in the semi-arid and arid deserts of Africa, the near east and south-west Asia with less than 200 mm of annual rain. The specific occurrence of locusts has not been found yet. The first plague of locusts reported in ancient Egypt during pharaonic times. In this century desert locusts plague was reported in 1926-1934, 1940-1948, 1949-1963, 1967-1969, 1986-1989 and in 2020.
Harm and Control:
Locusts do not harm humans or animals; but they definitely have the capability to leave us at starvation, by eating enormous amounts of food from agricultural fields as well as by devastating crops and damaging agriculture fields. For example, A swarm the size of Paris eats the same amount of food in one day as half the population of France; and the size of Sydney (Australia) eats the same amount of food in one day as Australia eats in 1.5 hours.
It is difficult to control them due to the extremely large area of their appearance, the limited resources for locust monitoring and control, the difficulty in organizing and implementing control operations and most importantly the difficulty in predicting outbreaks as the lack of periodicity of such incidents and the uncertainty of rainfall in locust areas. The ministry of agriculture at individual locations can carry out locust control operations with organophosphate chemicals applied in small concentrated doses (referred to as ultra-low volume (ULV) formulation) by vehicle-mounted and aerial sprayers.