Locusta migratoria (The migratory locust)
A polymorph insect.
They transform enormously behaviour and physically under the effect of overpopulation thus called polymorph insects.
There are two main phases:1.The solitary phase 2.The gregarious phase
As the density of the population increases the locust transforms progressively from solitary phase towards the gregarious phase with intermediate phases.
Solitaire = solitary phase -->> transiens congregans (intermediate form)-->> gregarious phase -->> transiens dissocians (intermediate form) -->> solitaire = solitary phase.
Pigmentation and size of the migratory locust
The pigmentation and size of the Desert locust vary according to its state: (gregarious or solitary or intermediate form) and of course its age: (larva, mature or immature adult).
The gregarious larvae have a yellow covering with black spots.
The solitary larvae are green or brown.
As an immature gregarious adult locust is pink, more or less darkened according to the temperature.
The solitary locust adult has a light brown covering.
Gregarious adults vary in size between 40 and 60 mm according to the sex.
They are smaller than the solitary adults.
Often confused with the desert locust, there some major differences between the migratory and desert locust.
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A Devasting Insect.
Locusts are highly mobile, and usually fly with the wind at a speed of about 15-20 km/h. Swarms can travel about 5-130 km or more in a day.
Locust swarms can vary from less than one square kilometre to several hundred square kilometres with 40 to 80 million locust per square kilometre.
An adult locust can consume its own weight (about 2 grams) in fresh food per day. For every million locusts, one tonne of food is eaten.
The migratory locust on video
Locusta migratoria video video Dive straight into a group of gregarious locusts, moving along with the classic Mozart tune, as a organised group in thirst for action. (picture on the right: still taken from the video Locusta migratoria produced by django media. Length 4min.
Still a major threat?
In Africa, the last serious widespread plague of Locusta m. migratorioides occurred from 1928 to 1942. Since then, environmental transformations have made the development of swarms from the migratory locust unlikely. However, the desert locust which is very similar to the African migratory locust remains a major threat.
Nevertheless potential outbreaks are constantly monitored as plagues can be devastating.
Locust survey and control are primarily the responsibility of the Ministry of Agriculture in locust affected countries and are operations undertaken by national locust units.
The Food and Agriculture Organization (FAO) of the United Nations provides information on the general locust situation to all interested countries and gives warnings and forecasts to those countries in danger of invasion.
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