ClassX Video Lessons Just add water: The garden insect that can turn into a plague – Jeffrey A. Lockwood
Imagine a massive swarm of insects stretching as far as you can see, with no leader or plan, just a mission to eat, breed, and move on. These are desert locusts, known for forming huge swarms that can destroy farms and pastures, leaving them barren. But here’s the thing: desert locusts aren’t always this destructive. Most of the time, they’re as harmless as regular grasshoppers.
So, what turns these ordinary insects into a crop-devouring plague? It all starts with their eggs, which are laid in the damp soil of deserts from North Africa to South Asia. During dry weather, these locusts live alone, munching on plants, growing wings, and eventually dying. However, when heavy rains come, everything changes.
Rain brings more plants for young locusts to eat, causing them to gather in large groups. As they bump into each other, their leg hairs get stimulated, releasing a hormone that makes them stick together even more. These crowded locusts produce waste that contains a pheromone, further transforming them. Their diet changes to include toxic plants, and they develop bright patterns to warn predators that they’re now poisonous. Small groups merge into massive bands, devouring all plant life in their path.
In about a month, these locusts grow 50 times their original size. Once fully grown, they take flight as a swarm. These swarms are so large that they were once thought to be a different species. A typical swarm has more locusts than there are people on Earth, covering hundreds of square kilometers. They can eat as much food in a day as a city of millions and travel up to 150 kilometers daily.
These swarms can even cross oceans. In 1988, a swarm crossed the Atlantic Ocean, likely resting on rafts made of their dead kin. On land, they look for moist soil to lay eggs, passing their swarming behavior to the next generation. Although an individual locust lives only three months, a plague can last up to a decade.
Desert locusts are particularly dangerous because they live in some of the world’s poorest countries, where many people rely on farming for food. By eating crops and pastures, these insects threaten the livelihoods of millions.
Thankfully, locust plagues don’t last forever. When the rains stop, vegetation becomes scarce, and conditions for laying eggs decline. As swarms die off, new locusts spread out, preventing them from forming swarms. Humans can help too. Researchers use satellite images to spot potential locust hotspots and alert local governments. While many countries use insecticides, some have found success with fungal diseases that kill locusts but are safe for people and the environment.
Unfortunately, modern practices can make things worse. Fields with a single crop are like a feast for locusts, and unpredictable weather from climate change makes swarms harder to predict. To prevent solitary locusts from becoming destructive swarms, we need to reduce carbon emissions, rethink agriculture, and reconsider our consumption habits.
Using craft materials, create a model that represents the life cycle of a desert locust. Include stages such as egg, nymph, solitary adult, and swarming adult. This will help you visualize how environmental changes impact their transformation.
In groups, simulate a locust swarm in the classroom. Assign roles such as locusts, farmers, and researchers. Discuss how each group is affected by the swarm and brainstorm solutions to mitigate the impact on agriculture.
Research different methods used to control locust swarms, such as insecticides, biological controls, and satellite monitoring. Present your findings to the class, highlighting the pros and cons of each method.
Participate in a debate about the role of climate change in locust swarming behavior. Prepare arguments for and against the idea that climate change exacerbates locust plagues, using evidence from the article and additional research.
Design a farm layout that could resist locust damage. Consider crop diversity, planting techniques, and natural barriers. Share your design with the class and explain how it could help prevent locust swarms from devastating crops.
The ravenous swarm stretches as far as the eye can see. It has no commanding general or strategic plan; its only goals are to eat, breed, and move on—a relentless advance that transforms pastures and farms into barren wastelands. These are desert locusts—infamous among their locust cousins for their massive swarms and capacity for destruction. But these insects aren’t always so insatiable. In fact, most of the time, desert locusts are no more dangerous than garden-variety grasshoppers.
So what does it take to turn these harmless insects into a crop-consuming plague? Desert locust eggs are laid in the damp depths of desert soil, in arid regions stretching from North Africa to South Asia. During the dry weather typical in these ecosystems, desert locusts live a solitary lifestyle. Adolescent hoppers will spend a few weeks foraging for plants before growing wings, reproducing, and dying.
However, when a region receives an abundance of rain, the scene is set for a startling transformation. Increased moisture supports more vegetation for newly hatched hoppers to eat, leading large groups to feed in close proximity. The frequent contact stimulates their leg hairs, triggering the release of a hormone that causes them to actively cluster even closer. Gluttonous crowds of locusts produce large amounts of waste, which carries a pheromone that furthers their transformation. The hopper’s diet shifts to include plants with toxic alkaloids. Soon, the locusts take on a striking pattern that warns predators of their newly poisonous nature. Smaller groups merge into bands of millions, which consume virtually all plant life in a kilometer-wide swath.
Roughly every week, they shed and expand their exoskeletons, growing to roughly 50 times their hatching weight in just one month. Finally, the metamorphosis is complete. The adults beat their translucent wings and take flight as a full-fledged locust swarm. In this gregarious phase, these long-winged, brightly colored creatures appear so different from their solitary counterparts that they were long thought to be a separate species. A typical swarm contains more locusts than there are humans on the planet, covering hundreds of square kilometers in a dense cloud. At these numbers, desert locusts easily overwhelm their predators. A large swarm can match the daily food intake of a city of millions, and flying with the wind, the insect invasion can travel up to 150 kilometers a day.
This living tornado can also cross large bodies of water. In 1988, a swarm even managed to traverse the Atlantic Ocean. The locusts likely formed rafts to rest at night before fueling up in the morning with a nourishing breakfast of their dead kin. While flying over land, they seek out moist soil to lay eggs. Swarming mothers transfer their gregarious condition to their offspring, making it likely that the next generation will form another swarm. This means that while an individual desert locust lives only three months, a plague can last up to a decade.
The potential for a years-long plague isn’t unique to desert locusts, but the region they inhabit makes the prospect particularly deadly. Their habitat spans some of the world’s poorest countries, largely populated by people who grow their own food. By consuming crops and pastures, these insects directly endanger a significant portion of humanity.
Fortunately, a desert locust plague doesn’t last forever. When a wet period ends, vegetation becomes scarce and egg-laying conditions decline. As existing swarms die off, new hatchlings spread out in search of food, creating enough distance to prevent solitary locusts from transforming. Human intervention can also help. Researchers use satellite imagery to identify regions at risk of becoming locust hotspots and alert local governments. While most countries fight back with chemical insecticides, some regions have found success using fungal diseases that are lethal to locusts but safe for people and the environment.
Unfortunately, other modern practices are exacerbating the threat. Fields densely packed with a single crop are like a table set for locusts. Erratic weather caused by climate change makes swarms harder to predict. If we plan to discourage solitary locusts from becoming catastrophic crowds, humans need to cut carbon emissions, rethink our agriculture, and generally reconsider our own consumption patterns.
Locusts – Locusts are a type of grasshopper that can form large groups and cause significant damage to crops. – During the summer, the locusts invaded the fields, destroying the farmers’ crops.
Swarm – A swarm is a large group of insects moving together, often causing destruction. – The swarm of bees moved quickly across the garden, pollinating the flowers.
Eggs – Eggs are the reproductive bodies laid by female animals, from which offspring develop. – The frog laid her eggs in the pond, where they would hatch into tadpoles.
Soil – Soil is the upper layer of earth in which plants grow, composed of organic and inorganic materials. – The rich soil in the valley was perfect for growing vegetables.
Plants – Plants are living organisms that typically grow in soil and use sunlight to make their food through photosynthesis. – The plants in the greenhouse thrived due to the controlled environment.
Pheromone – A pheromone is a chemical substance released by animals that influences the behavior of others of the same species. – Ants use pheromones to communicate and find their way back to the nest.
Diet – Diet refers to the kinds of food that an organism regularly consumes. – The panda’s diet mainly consists of bamboo, which it eats for most of the day.
Crops – Crops are cultivated plants grown on a large scale for food or other uses. – The farmer rotated his crops each season to maintain soil fertility.
Climate – Climate is the long-term pattern of weather conditions in a particular area. – The tropical climate of the region supports a diverse range of wildlife.
Emissions – Emissions are substances, often gases, released into the atmosphere from various sources. – Reducing carbon emissions is crucial to combating climate change.
