Flying swarm
Flying adult
2.5-5 months
Nonflying
nymph
24-95 days
Egg
10-65 days
MAJOR
LIFE CYCLE
STAGES
relative size
SOLITARY
NYMPH
actual size
CNS
Brain
SIGHT &
SMELL
TOUCH Thoracic ganglia
serotonin
released
Nerve
Sensory
neuron
Dendrite
Signal
to CNS
FEMUR
FOOT Hair
EXPLORE | DECODER
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.
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.
1
2
The release of serotonin is
caused by stimulation of the
leg hairs, as well as the sight
and smell of other locusts.
BY TAYLOR MAGGIACOMO
HOW TO SET OFF A
PLAGUE OF LOCUSTS
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. In 2004 a million Malians faced famine after locusts consumed
90 percent of their country’s cereal crops. Changes in locusts’ behaviors
and physical traits can eventually be reversed if locusts get isolated, or
they can persist and be passed on to offspring. —KAYA LEE BERNE
Preventing a plague
Weather patterns and histori-
cal locust records help experts
predict where swarms might
form. Once identified, an area
is sprayed with chemicals to kill
locusts before they can gather.
28 NATIONAL GEOGRAPHIC