FAQ Locust

How far and how fast can Desert Locusts migrate?

Desert Locusts usually fly with the wind at a speed of about 16-19 km/h depending on the wind. Swarms can travel about 5-130 km or more in a day. Locusts can stay in the air for long periods of time. For example, locusts regularly cross the Red Sea, a distance of 300 km. Solitary Desert Locust adults usually fly at night whereas gregarious adults (swarms) fly during the day.

Do swarms fly at night?

Occasionally during periods of unusually warm temperatures, swarms will fly during the early evening but rarely will they continue to fly during the entire night unless they happen to be over water (sea, ocean).

How big swarms and how many locusts are there in a swarm?

Locust swarms can vary from less than one square kilometre to several hundred square kilometres. There can be at least 40 million and sometimes as many as 80 million locust adults in each square kilometre of swarm.

What is the difference between hopper groups and bands?

One should carefully observe their behaviour and appearance. Groups will contain some hoppers that are starting to behave in the same manner but not all individuals will be doing this. Their colours are a mixture of those commonly associated with solitarious and gregarious individuals, that is, green with some black markings. On the other hand, bands consist of all or close to all of the locusts behaving in the same manner. Their appearance is distinctive hoppers in bands are either black (when young) or yellow with black markings.

What is the difference between adult groups and swarms?

One should carefully observe their behaviour and their appearance. Groups will contain adults that are starting to behave in the same manner but not all individuals will be doing this. Their colours are a mixture of those commonly associated with solitarious and gregarious individuals, that is, a pinkish (immature) or yellowish (mature) appearance. On the other hand, swarms consist of all or close to all of the adults behaving in the same manner. Their appearance is distinctive: pink for immature swarms and yellow for mature.

What is the relationship between locusts and ecology?

When conditions are favourable for reproduction, locust numbers increase and when they are not, numbers decrease either by natural mortality or through migration. For the Desert Locust, favourable conditions for breeding are (1) moist sandy or sand/clay soil to depths of 10-15 cm below the surface, (2) some bare areas for egg-laying, and (3) green vegetation for hopper development. Often favourable conditions may exist in the desert but there are no locusts present. Therefore, the presence of moist soil and green vegetation does not automatically mean that there are locusts around.

Why do locusts change their behaviour?

As Desert Locusts increase in number and become more crowded, they change their behaviour from that of acting as an individual (solitarious) insect to that as acting as part of a group (gregarious). The appearance of the locust also changes: solitary adults are brown whereas gregarious adults are pink (immature) and yellow (mature).

Why is it important to collect information on locust behaviour and who will use this?

By carefully observing the locust behaviour, the experienced Locust Field Officer can often see the first signs of the change in locust phase; that is, from solitarious to gregarious and vice versa. This can be seen by watching how the locusts behave individually and together; for example, are they starting to behave similarly concentrate or form groups? This is important in deciding which infestations are significant, which pose a threat and which should be controlled.

Will locusts lay eggs in areas of dense vegetation?

No. Locusts require bare ground for laying eggs. In areas of dense vegetation, there is often very little bare ground.

Do Desert Locusts have an overwintering stage?

No. But under cool, dry conditions, the development of any stage (egg, hopper, adult) will be longer.

Pages