Locusts are a type of short-horned grasshopper that can undergo a transformation from a solitary existence to forming highly destructive swarms. Unlike typical grasshoppers that remain individual, locusts possess the ability to change their behavior, physiology, and appearance in response to specific environmental conditions, leading to their gregarious phase. This article explores the dietary habits of these insects, detailing what they consume, how they feed, and the significant impact their feeding has on ecosystems and human populations.
What Locusts Primarily Consume
Locusts are herbivores, consuming a wide range of plant materials. Their diet primarily consists of soft greens, grasses, and foliage. Preferred food sources include economically important cereal crops such as wheat, corn, barley, rice, sorghum, and oats. Beyond grains, they also feed on leafy vegetables like spinach, tomatoes, beets, onions, carrots, and potatoes, along with fruits like apples and pumpkins.
As generalist feeders, locusts can consume nearly any green plant available. They eat leaves, stems, flowers, seeds, and even the bark of plants. While they prefer certain vegetation, they will consume drier grasses or greenery when lush food sources become scarce. Although their diet is almost exclusively plant-based, in extreme conditions where water is limited, locusts have been observed resorting to cannibalism for survival.
How Locusts Devour Vegetation
Locusts possess specialized chewing mouthparts, called mandibles, expertly designed for processing plant material. Their mandibles are robust, hardened structures shaped like pincers, with sharp cutting surfaces and grinding surfaces. These mandibles move sideways, efficiently cutting and pulverizing tough plant fibers. Accessory mouthparts, including maxillae and a hypopharynx, assist in manipulating food for digestion.
An adult Desert Locust can consume approximately its own body weight in fresh food each day (around 2 grams). While this individual consumption seems small, it scales dramatically in swarms. A small swarm, spanning one square kilometer, can contain between 40 million and 80 million locusts. Such a swarm can collectively consume the same amount of food in a single day as about 35,000 people. Larger swarms can be immense; for instance, a swarm in Kenya in 2020, covering 2,400 square kilometers, consumed up to 1.8 million metric tons of green vegetation daily, equivalent to feeding 81 million people.
The Broader Impact of Their Feeding
The voracious appetite and dietary flexibility of locusts, especially in their swarming phase, make them one of the most destructive migratory pests globally. Their ability to consume vast quantities of vegetation has severe consequences for agriculture. Locust swarms destroy crops, pastures, and fodder, leaving behind barren landscapes.
This widespread destruction leads to food shortages and increased food prices, impacting food security in affected regions. Areas with fragile food systems, such as parts of Africa and Asia, are vulnerable to these infestations. The economic repercussions are substantial, as livelihoods are shattered and regional economies can be crippled by crop damage. Locust outbreaks are becoming more frequent and intense, with climate change contributing to conditions that favor their breeding and spread. The financial burden of managing these plagues is immense; for example, controlling the 2003-2005 locust plague cost over $450 million and resulted in an estimated $2.5 billion in crop damage.