Sight &

smell

Brain

CNS

touch

Hair

Foot

The release

of serotonin is caused by stimulation of the leg hairs, as well as the sight and smell of other locusts.

Dendrite

Femur

Sensory

neuron

Signal

to CNS

Gregarious

nymphs

Pearl millet

Pennisetum

glaucum

Flying swarm

Flying

gregarious

adult

Solitary vs. gregarious brain

Frontal view

Optic lobe

(sight)

Midbrain

(general processing)

Antennal lobe (smell)

Antenna

Brain

Eye

FEMUR

Extensor muscle

(jumping)

Flexor muscle

(bending)

Solitary femur

18% greater volume

By Taylor Maggiacomo

and Kaya Lee Berne

Visualize a swarm of 70 billion flying insects, covering 460 square miles—about 1.5 times the size of New York City—and devouring more than 300 million pounds of crops in one day. That’s how big a single swarm can get. Plagues, made up of multiple swarms, are referenced in the Bible and the Quran. Of the thousands of grasshopper species, only 22 can be described as locusts. They’re distinguished by their ability to transform from a solitary state—actively avoiding other locusts—into a social, or “gregarious,” state in which masses of them darken the sky, ravage the land, and terrorize inhabitants.

the life of a locust

Locusts move through several phases before maturing into flying adults. At any point in that process they can turn gregarious—if conditions are right. Transformations in their behavior and physical traits can eventually be reversed, or they can persist and be passed on to offspring.

Desert locust

Schistocerca gregaria

relative size

Egg

10-65 days

Nonflying nymph

24-95 days

Solitary

Gregarious

Flying adult

2.5-5 months

Gregarious

Solitary

Development of a plague

1

An unintentional gathering

Always in search of food, solitary locusts are forced together during dry spells, when vegetation dies off and leaves minimal areas of green within the desert.

2

Sudden transformation

Within hours of crowding, a boost of serotonin in the central nervous system (CNS) spurs behavioral changes such as rapid movements, sociability, increased self-grooming, and a more varied appetite.

3

Breeding and feeding frenzy

Returning rains provide moist breeding grounds. New generations form groups that forage in unison. Once their wings grow, the herds become flying swarms in search of more food and habitat.

A toxic new look

Swarming locusts turn bright yellow—a warning to birds, reptiles, and other predators that they may be unappetizing or poisonous.

4

Flying apocalypse

Although uncommon, a major plague begins when swarms, often traveling 30 to 60 miles a day, develop over multiple regions. Without intervention, plagues can last years, until natural die-off occurs.

Altered anatomy

The switch to the gregarious state includes physical changes such as a larger brain and shorter legs.

Brain boost

Transition to the gregarious phase causes the brain—especially the midbrain—to grow larger, perhaps for more complex information processing.

Increased endurance

Offspring of gregarious locusts develop smaller femurs. Their hops are shorter but use less energy to cover the same distance.

where swarms occur

The species with the most economic impact, the desert locust, threatens one-fifth of Earth’s land area and one-tenth of the global population. Over 60 countries are susceptible to swarms. Locusts in the solitary phase occupy and breed in smaller regions. The last major plague, from 1986 to 1989, hit North Africa and the Middle East. Many swarms died while crossing the Atlantic; some reached the Caribbean.

Desert locust

Schistocerca gregaria

Preventing a plague

Weather patterns and historical locust records help experts predict where swarms might form. Once identified, an area is sprayed with chemicals to kill locusts before they can gather.

Riley D. Champine, NGM Staff. SOURCES: Stephen Rogers, University of Cambridge; STEPHEN J. SIMPSON, UNIVERSITY OF SYDNEY; Keith Cressman, FAO Desert Locust Information Service

Sight &

smell

Brain

CNS

touch

Hair

Foot

Dendrite

The release of serotonin is caused by stimulation of the leg hairs, as well as the sight and smell of other locusts.

Femur

Sensory

neuron

Signal

to CNS

Gregarious

nymphs

A toxic new look

Swarming locusts turn bright yellow—a warning

to birds, reptiles, and other predators that they may be unappetizing or poisonous.

Pearl millet

Pennisetum

glaucum

Flying swarm

Flying

gregarious

adult

Solitary vs. gregarious brain

Frontal view

Optic lobe

(sight)

Midbrain

(general processing)

Antennal lobe (smell)

Antenna

Brain

Eye

FEMUR

Extensor muscle

(jumping)

Flexor muscle

(bending)

Solitary femur

18% greater volume

By Taylor Maggiacomo and Kaya Lee Berne

Visualize a swarm of 70 billion flying insects, covering 460 square miles—about 1.5 times the size of New York City—and devouring more than 300 million pounds of crops in one day. That’s how big a single swarm can get. Plagues, made up of multiple swarms, are referenced in the Bible and the Quran. Of the thousands of grasshopper species, only 22 can be described as locusts. They’re distinguished by their ability to transform from a solitary state—actively avoiding other locusts—into a social, or “gregarious,” state in which masses of them darken the sky, ravage the land, and terrorize inhabitants.

the life of a locust

Locusts move through several phases before maturing into flying adults. At any point in that process they can turn gregarious—if conditions are right. Transformations in their behavior and physical traits can eventually be reversed, or they can persist and be passed on to offspring.

Desert locust

Schistocerca gregaria

relative size

Egg

10-65 days

Solitary

Gregarious

Nonflying nymph

24-95 days

Flying adult

2.5-5 months

Development of a plague

1

An unintentional gathering

Always in search of food, solitary locusts are forced together during dry spells, when vegetation dies off and leaves minimal areas of green within the desert.

2

Sudden transformation

Within hours of crowding, a boost of serotonin in the central nervous system (CNS) spurs behavioral changes such as rapid movements, sociability, increased self-grooming, and a more varied appetite.

3

Breeding and feeding frenzy

Returning rains provide moist breeding grounds. New generations form groups that forage in unison. Once their wings grow, the herds become flying swarms in search of more food and habitat.

4

Flying apocalypse

Although uncommon, a major plague begins when swarms, often traveling 30 to 60 miles a day, develop over multiple regions. Without intervention, plagues can last years, until natural die-off occurs.

Altered anatomy

The switch to the gregarious state includes physical changes such as a larger brain and shorter legs.

Brain boost

Transition to the gregarious phase causes the brain—especially the midbrain—to grow larger, perhaps for more complex information processing.

Increased endurance

Offspring of gregarious locusts develop smaller femurs. Their hops are shorter but use less energy to cover the same distance.

where swarms occur

The species with the most economic impact, the desert locust, threatens one-fifth of Earth’s land area and one-tenth of the global population. Over 60 countries are susceptible to swarms. Locusts in the solitary phase occupy and breed in smaller regions. The last major plague, from 1986 to 1989, hit North Africa and the Middle East. Many swarms died while crossing the Atlantic; some reached the Caribbean.

Desert locust

Schistocerca gregaria

Preventing a plague

Weather patterns and historical locust records help experts predict where swarms might form. Once identified, an area is sprayed with chemicals to kill locusts before they can gather.

Riley D. Champine, NGM Staff. SOURCES: Stephen Rogers, University of Cambridge;

STEPHEN J. SIMPSON, UNIVERSITY OF SYDNEY; Keith Cressman, FAO Desert Locust Information Service