By Scott Solomon, Rice University
As desert locusts fly in search of food, they use their antennae to determine their flight speed. In fact, the desert locust’s flight speed holds the record for the fastest recorded flight speed of any insect at 20.5 miles per hour. But how do they achieve these remarkable speeds? Researchers at Oxford University tried to answer this question through a series of experiments.
High Speeds and Long Distances
Researchers at Oxford University used high-speed cameras to record the precise movements of desert locusts’ wings as they fly in a laboratory flight cage. By burning oil to create smoke, the way that the locust’s wing flaps affect the surrounding air becomes visible.
The researchers found that the impressive flying abilities of the desert locust are accomplished not only by the size and shape of the locust’s wings but also by the ways the wings bend and flex. By making their wing movements more efficient, desert locusts are not only able to fly at high speeds but also over long distances.
Migrating desert locusts regularly fly 90 miles or more in a single day, and swarms of locusts have even been documented crossing large areas of open water like the Red Sea, which is about 180 miles wide. In 1988, a swarm of locusts crossed the Atlantic Ocean from West Africa to the Caribbean, a distance of more than 3,000 miles!
This article comes directly from content in the video series Why Insects Matter: Earth’s Most Essential Species. Watch it now, on Wondrium.
Strong Wings Need Strong Legs
The wings are controlled by muscles in the thorax, the middle segment of an insect’s body. The main function of the thorax is locomotion. The thorax itself is divided into three segments. Most insects have two pairs of wings, with the front pair attached to the middle segment of the thorax, and the second pair of wings attached to the third thoracic segment, closest to the rear of the insect.
Each of the three segments of the thorax also has a pair of legs, giving insects six legs in total—one of the easiest ways to tell insects apart from other arthropods.
Locusts have enlarged hind legs with powerful muscles for jumping. The legs themselves are made up of five distinct segments.
The coxa, the segment of the leg that attaches to the thorax, is usually very small. The next segment is the trochanter, which is also small. The next two segments are the femur and the tibia, typically the longest segments of the leg. The final segment is the tarsus, which is made up of five sub-segments including two at the tip that act as claws that allow the insect to get a strong grip.
Strength in Numbers
Interestingly, the desert locust can switch back and forth between two different ‘phases’ that have physical and behavioral differences. In the solitary phase, the locusts are brown and green in color, making them blend into the background of the vegetation they consume. They move slowly, but their hind legs have long femurs that help them escape from predators.
As the name suggests, locusts in the solitary phase mostly keep to themselves but if the number of individuals in the population increases (for example, if rainy conditions lead to a sudden boom in food plants), the locusts can transform into their gregarious phase.
Gregarious phase locusts develop a bright yellow coloration with black bands that act as a warning to potential predators. Their femurs shrink, reducing their jumping distance and speed by about 25% according to one study. In the gregarious phase, desert locusts become attracted to other members of their species and form swarms of up to 80 million individuals.
Being part of a swarm makes it less likely that any one individual will be eaten by a predator, allowing them to divert energy away from the muscles needed for jumping and towards other needs, like flight muscles.
Breathing while Flying Fast
An insect’s abdomen houses many of the internal organs. The digestive, respiratory, waste management, endocrine, and reproductive systems are all housed mostly within the abdomen. The abdomen of the desert locust is elongated and subdivided into 11 segments.
Insects don’t have lungs. Small holes called spiracles form the entrance to the respiratory system, which provides oxygen to all the tissues of the body. Air enters the spiracles and travels through a system of branched tubes called tracheae which lead to each part of the body.
By contracting muscles in the abdomen, air sacs located along the trachea are compressed, pushing air through the respiratory system. The spiracles can be opened and closed independently, allowing air to enter some spiracles and exit others, creating a one-way path of airflow.
When locusts are flying, they contract their abdomens more rapidly, pumping more oxygen to their flight muscles.
Common Questions about the Miracle of the Desert Locust’s Flight
A desert locust’s flight speed is influenced by both the shape of the wings and its movement. The movement of the wings in the case of this insect is incredibly efficient, so much so that the desert locust holds the record for the fastest flight speed of any insect.
Being part of a swarm makes it less likely that any one individual will be eaten by a predator. This lets the desert locusts use more energy on their flight speed than on jumping and evading predators.
The desert locusts don’t have lungs. Small holes called spiracles form the entrance to the respiratory system, which provides oxygen to all the tissues of the body. Air enters the spiracles and travels through a system of branched tubes called tracheae which lead to each part of the body.
