Why do grasshoppers fly in groups?

The Bible once described them as a pandemic of insects following the wind and cleaning everything in the Egyptian land. Now, scientists have found the right time when a chaotic flock of locusts became a unified, organized and sometimes awe-inspiring mass.

Photo: LiveScience When examining a group of desert grasshoppers, the researchers found that at low densities, the insects flew in disarray without any organization, each taking a separate path. But when the group density increased, locusts cornered into an orderly row, and began to fly in the same direction.

This finding could help control insects that damage crops or spread diseases.

The mechanisms behind this rapid transition from chaos to this order are also helpful in helping scientists understand how animals take advantage of group behavior in feeding and migrating. and flee the enemy.

" Collective movement is everywhere around us ," said lead researcher Jerom Buhl of the University of Sydney, Australia. " We are all familiar with the spectacle of conquering long lines of endless food, clouds of birds or fish that move in perfect harmony and even people at high hours. point at a subway station or at a roundabout ".

Previous theoretical models have shown that animals go through a transition from chaos to order when trying to line up with their neighbors.

Buhl and his colleagues decided to test this theory by dropping grasshoppers into a yard and filming the process they linked together to form groups. They found that when only a few of them gathered, they did not form a block. When the group increased to 10 to 25 members, grasshoppers began to get closer, but still did not move uniformly.

Only when the team dropped about 30 grasshoppers into the yard, the insects began to line up and fly in the same direction. They have reached the "critical point".

" The main benefit of this seems to be that they will be safer than flying alone, " said team member Stephen Simpson, also from the University of Sydney. " When the population density is so high that you cannot hide yourself forever, you will be safer in the eyes of the enemy if you join the crowd. Once you join the group, you must fly to the search path. food ".

Even so, the operation of locusts still carries a bit of mystery because they have no leader and each can only communicate with them right next to it. " Grasshoppers do not exhibit any communication behaviors when they flock. Perhaps, their main interaction is due to visual and physical contact - but this we will have to verify in the future. "Buhl said.

T. An