Locusts: What to Know

Medically Reviewed by Poonam Sachdev on January 16, 2023
6 min read

Locusts have been agricultural pests for almost as long as humans have cultivated plants for food. They cause millions of dollars in crop damage every year. They can even create food insecurity problems and destroy entire livelihoods in certain regions of the world. 

There are many different species of locusts around the world, and they’re all capable of forming massive swarms of thousands to millions of individuals. Learn about the ones in your area so you can prepare for their devastating feeding frenzies.

Locusts are in the Orthoptera order, which also contains crickets, katydids, and other grasshoppers. Most locusts belong to the Acrididae family and are members of several different genera.

Scientists are still trying to determine the exact number of locust species in the world today. This is tricky because there are so many different varieties of these insects. For example, there are over 700 species of locusts — and other grasshoppers — living in Australia alone.

All species of locusts are short-horned grasshoppers that sometimes form large, hungry swarms. The swarms migrate together and devastate most of the plant life in their path.

Most locust species only form swarms when a lot of them are present in one spot. The high population density causes them to undergo both physical and behavioral changes that are more suitable for life in a swarm. This biological phenomenon is called polyphenism.

What do locusts look like? Members of each species of locust have their own average sizes and coloration patterns. Individuals within a species develop differently when they’re in a swarm than they do when surviving on their own. Their swarm forms are also known as their gregarious forms. 

For the most part, they resemble chunky grasshoppers with very strong wings. The wings typically don’t form until they reach the adult stage of their life cycle.

Examples of colors that you could see on a locust’s adult body include: 

  • Brown 
  • Green
  • Straw
  • Gray

Some adults also have distinct patterns on their bodies, like white stripes. Within a species, an individual's exact color can depend on whether it’s living by itself or in a swarm. 

Body sizes can range from 1.25 inches to over 2 inches long. In many species, the males are smaller than the females. 

What’s the locust's life cycle? Throughout their lifetime, locusts undergo incomplete metamorphosis. This means that they never form maggot-like pupae. Instead, young locusts — called nymphs — are mostly just smaller versions of their adult forms. 

All locust species hatch from eggs and then grow through a series of nymph stages, called instars. The exact number of instars depends on the locust species. Many have five separate instar stages. To grow larger, they molt between each stage.

Many species only survive for a single season, but others can last for a year or two. 

What do locusts eat? Locusts are herbivores. This means that they survive off of plants. The exact plants vary from one species to the next. but most enjoy surviving off of human crops including: 

Most species prefer plant leaves, but they can also eat flowers and other plant parts.

Examples of locust species are described below.

Locusta migratoria. Members of this species are commonly called migratory locusts. These are large, blocky locusts. Solitary adults take on green and brown tones. Their bodies are more straw-colored in their swarm form. This species mainly consumes grasses — like sorghum, wheat, and corn.  They thrive in a wide variety of agricultural areas around the globe.

Austracris guttulosa. The spur-throated locust is named after a distinct protrusion that you can find between its front legs. Adults are pale brown with white stripes. They feed on a wide variety of crops, but most people don’t consider them as problematic of a pest as other species.

Schistocerca gregaria. This species is also known as the desert locust. It’s one of the most devastating agricultural pests alive today. It’s threatened the livelihoods of millions of people throughout Africa, Asia, and the Middle East. Desert locusts have yellowish bodies with distinct black stripes.

Melanoplus spretus. This is the Rocky Mountain locust. A living example hasn’t been seen since 1902, so experts believe that they’re extinct. The species formed a final swarm in 1874 that was composed of over 12.4 trillion insects. Any crops that were growing in this swarm’s path were destroyed.

You can find different species of locusts living in most parts of the world. Many species particularly enjoy agricultural areas because these provide them with plenty of food to choose from.  

Swarms only form when certain environmental conditions are met. Researchers are still trying to understand exactly what conditions are required for swarming in every locust species.

When locusts swarm, they can appear and disappear very suddenly. In this case, the sign will be the large cloud of insects descending on your home or field. But by this time it’s too late.

Unique environmental conditions, like the amount of seasonal rainfall and the ambient temperature, can cause each species to swarm. Learn about the species that are most common in your area. Then figure out the environmental conditions that are likely to cause this species to swarm. Take more precautions in years that match these conditions than in years that don’t.

For the most part, locusts are only a major pest in the agricultural industry. For some, the economic impact of locusts can be devastating. Locust swarms can take out an entire season's worth of crops in a single feeding session. This can translate to 100 percent crop loss in the span of a few hours. 

A swarm won’t hesitate to devastate your backyard garden if they happen to be passing through. 

Do locusts bite? Locusts are capable of biting but aren’t known for biting humans. If you feel pain after interacting with a locust, it’s probably because they stabbed you with their strong legs or the sharp spurs that are found on some species.

Locusts shouldn’t cause you a lot of physical harm. You shouldn’t require treatment after interacting with locusts.

But you should always keep an eye out for signs of an allergic reaction if you’re bitten or stung by any type of insect. Get immediate medical attention if you start to experience any serious symptoms like difficulty breathing, swelling in your throat or face, and hives.

Managing locusts is a tricky problem that requires large-scale coordinated efforts. Multiple organizations are responsible for tracking their yearly movements and giving farmers early warnings when swarms start to form in any given area. 

The main way to manage them at present is with large amounts of commercial pesticides. But this practice can damage the environment in other serious ways. 

Researchers are currently exploring new ways to sustainably manage these pests. A lot of this involves understanding why swarms form in the first place so we can keep this from happening.

On the home garden front, you can keep plants safe by moving them indoors or covering them up when you know that a swarm is on the way.

Locusts have behaved as devastating pests for thousands of years. Humanity is still trying to figure out how to manage these problematic insects. But they’re also fascinating biological models. Learn about the types of locusts that are present in your area so you know to protect your plants when a swarm is on its way.