Migratory Locust

Dr. Jekyll and Mr. Hyde

Migratory locusts are rightfully feared. They can aggregate into swarms of one billion individuals and destroy all vegetation in their path. The biggest swarm observed probably consisted of 12.5 billion grasshoppers! A swarm can cover an area of several hundred square kilometres and travel over hundred km in one day.

Appearance and characteristics

They do not always swarms. They occur in two variants. One brown and red that is swarming and one green that is more or less solitary and stationary.

When a population of stationary migratory locusts increase in numbers so much that they begin to bump into each other, the half-grown nymphs begin to aggregate into dense "gangs" and pass into the swarm phase. This is controlled by pheromones that are the fragrances that grasshoppers use to communicate with each other.

Because they do not have wings yet, the nymphs walks instead. After just over two miles, depending on the terrain, the wings develop and they begin their adult swarming life.

An adult migratory locust lives only a couple of months, but it may take several years before the whole swarm decreases in number and the locusts return to the solitary, stationary phase again. Even though migratory locusts are flying in swarms of up to a billion grasshoppers, they never collide with each other. This is possible because the locust has two big facet eyes and three simple ocellus eyes.

If something approaches from within a very narrow section of the front field of vision, a signal is sent flash-fast toa special, very large brain cell that manages the information. When the flying locust has perceived the object, it only takes 0.111 seconds for it to swerve. 0.065 seconds goes for visual impression processing and 0.050 seconds for the wing stroke.

To handle the fast turn, it uses both the head, wings, back and legs.

Feeding and catching

A migratory locust eats plants corresponding to its own weight every day. Although it only weighs a few grams, a swarm of one billion of them eats a thousand tons a day! No wonder the farmers fear them.