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Madagascar, first locusts spotted

Madagascar, first locusts spotted


The helicopter took off to carry out an extensive aerial survey between Antananarivo and Majunga in Madagascar, stopping at Maevatanana to refuel. The objective of the survey was to determine the level of locust infestation on the western side of the Betsiboka plain.

First locusts spotted / premiers criquets repérés

With its survey team aboard, the helicopter had left Ivato airport barely an hour earlier when, from the corner of his eye, the scout noticed a moving silvery shimmer.

Doubt began to set in – could it be locusts?

Fully alert, the scout scanned the area to confirm what he thought he had seen. Once again, he saw the shimmer, so he asked the pilot to turn around and fly at a lower altitude.

It was indeed locusts, and more specifically, a small, 120 ha light flight (A light flight is composed of a low density (2 500 to 10 000 adult locusts/ha), loosely-grouped flying adult locusts). The helicopter landed in the middle of the flight and the turbine was switched off; villagers from the surrounding area began to congregate.

The locusts, of dark orange to wine-red colour, were everywhere - in the air, settled on tufts of dry grass, on the bare ground and in the rice fields slightly lower down.

The scout explained the reasons for his presence to the villagers and gathered information about the frequency of the locusts’ movements, the damage caused to crops, the date of the last rains, etc.

He then photographed the surrounding vegetation and the locusts, capturing a few of them. The state (very green, drying out or dry), nature (pastures, crops, shrubs, etc.) and the abundance of the vegetation are essential indicators to anticipate locust populations’ development accurately. Vegetation serves as a shelter for locusts but above all, it is their food source. The captured locusts will enable the surveyor to determine the phase (pigmentation, behaviour and morphology criteria) and the stage of the locusts’ development (young, able to breed -i.e. mature adults-, those that have already laid eggs or old). Both types of information are crucial to establish priorities for future anti-locust operations. 

Some of the locusts fly, collide with the surveyor and then land; others feast on the young, green rice shoots while others still continue their flight, carried by the wind; the stragglers will catch up with them a little further on and it will then be their turn to rest or eat. This is their customary way of flying in a group, known as a “rolling swarm” because there is always one part of the population in flight and another on the ground, eating or resting, which will then take flight as the first locusts alight. 

Then, after a little less than an hour observing the light flight and holding discussions with the villagers, the team sets off again to continue its survey, having noted the exact location of the locust population using GPS (GPS is a global positioning system that uses satellite triangulation).

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