Locusts are short-horned grasshoppers that undergo a physiological and behavioral shift, known as phase polyphenism, allowing them to form massive, highly mobile swarms. This capacity to transition from a solitary, relatively harmless state to a gregarious, devastating pest is what defines a locust. A single swarm can comprise billions of individuals, posing an enormous threat to agriculture and food security across continents.
The Natural Diet of Locusts
Locusts are generalist herbivores, but their feeding preferences center on vegetation that supports their high-energy lifestyle. They primarily consume the leaves and tender tissues of plants, preferring monocotyledonous species. This includes grasses and cereal crops like maize, wheat, rice, and millet, which are often the first targets of a newly formed swarm.
The volume of food they consume is directly tied to their destructive potential and migratory behavior. An adult locust can consume plant matter equivalent to its own body weight, about two grams, every day. This rapid consumption rate fuels their high metabolic demands, especially during the migratory phase. Locusts also derive the majority of their necessary moisture from the plants they eat, driving them to relentlessly pursue fresh, green vegetation.
Nutrient Ratios and Swarm Formation
The switch from the solitary phase to the gregarious, swarming phase is triggered by both crowding and diet quality. High density, often caused by drought followed by rapid vegetation growth, leads to physical contact, primarily on the hind legs. This tactile stimulation increases serotonin levels in the locust’s central nervous system, initiating the behavioral and physiological changes associated with swarming.
This shift is linked to nutrition, specifically the ratio of protein to carbohydrates (P:C) in their diet. Migratory locusts perform best on carbohydrate-biased diets, which provides the high energy needed for sustained flight and migration. When resources become depleted or unbalanced, nutritional stress, particularly a protein deficiency, triggers aggressive, swarming behavior. This deficiency can even lead to cannibalism as individuals pursue the needed protein, contributing to the rapid, collective movement of the swarm.
Feeding Mechanics and Consumption Rate
Consumption is enabled by specialized mouthparts designed for processing tough plant material at a high volume. Locusts possess powerful mandibles that rapidly cut and shear off foliage. The efficiency of these mandibles is enhanced by deposits of zinc (Zn) on their cutting edges, which increases the hardness and wear resistance of the cuticle.
This zinc-enriched armor is necessary because the plants they consume, particularly grasses, contain abrasive silica microparticles called phytoliths as a defense mechanism. The robust, hardened mandibles allow them to overcome this defense and maintain a continuous, high rate of feeding. This efficiency, combined with the sheer numbers in a swarm, explains why 80 million adults per square kilometer can consume up to 160 tons of vegetation daily, devastating an agricultural area in a matter of hours.
Diet Requirements for Captive Locusts
For those keeping locusts as feeder insects, providing a proper diet ensures high nutritional value for the pets consuming them. Captive locusts thrive on a steady supply of fresh, pesticide-free vegetation, which provides both food and hydration. Appropriate food sources include fresh grasses, leafy greens like cabbage and dandelion, and vegetables such as carrots and lettuce.
Hydration is provided indirectly through these fresh foods, as traditional water dishes pose a drowning risk. To supplement moisture, breeders often use commercially available bug gels or moist cotton wool, allowing the insects to drink droplets safely. The practice of “gut-loading” is a common strategy where the insects are fed a diet rich in beneficial nutrients, such as calcium and Vitamin E, just before being fed to a reptile to maximize the nutritional benefit passed on to the pet.