Locusts do not have larvae in the way beetles or butterflies do. Because locusts undergo incomplete metamorphosis, their immature stages are called nymphs, or more commonly “hoppers.” These wingless juveniles hatch from eggs laid in soil, pass through five or sometimes six molting stages called instars, and gradually develop into the winged adults capable of long-distance flight. The hopper stage is where much of the biological drama unfolds, because it is during these weeks on the ground that a solitary, inconspicuous grasshopper can transform into part of a marching, crop-devouring swarm.
Why “Locust Larvae” Is the Wrong Term, and What to Call Them Instead
Insects that undergo complete metamorphosis, like moths or flies, have a distinct larval stage (caterpillar, maggot) that looks nothing like the adult. Locusts skip that step entirely. A newly hatched locust already resembles a tiny adult, just without functional wings. Each time the nymph outgrows its exoskeleton, it sheds the old cuticle in a process called molting and enters a new instar, slightly larger and with more developed wing buds. The standard path for desert locusts and migratory locusts is five nymphal instars, but that number is not fixed. In desert locusts, smaller hatchlings and females are far more likely to undergo an extra molt: roughly 13.5 percent of males add a sixth instar compared with about 46.5 percent of females, and the probability climbs sharply when the hatchling’s body weight is low at birth.
1PLOS ONE. Extra Molting and Selection on Nymphal Growth in the Desert LocustMolting itself depends on precise timing of protein production in the cuticle. In migratory locusts, key cuticular proteins stay at low levels through most of a nymphal instar and then spike toward the end, signaling the body to prepare the new exoskeleton underneath the old one.
2PubMed. Cuticular protein LmTwdl1 is involved in molt development of the migratory locustFrom Egg to Hopper
Female locusts lay egg pods in moist soil, depositing dozens of eggs surrounded by a frothy secretion that hardens into a protective sheath. The eggs can sit dormant through dry spells, but once conditions are right, temperature governs when they hatch. Lab experiments simulating outdoor conditions show that rising soil temperature in the morning is the main trigger for hatching, which helps explain why locusts in different seasons tend to emerge at similar times of day.
3Physiological Entomology. The hatching time of Locusta migratoria under outdoor conditions: role of temperature and adaptive significanceA freshly hatched locust nymph is a pale, soft-bodied creature only a few millimeters long. Within minutes its cuticle begins to harden and darken. Over the next few weeks it will molt repeatedly, roughly doubling in size at each instar. By the third instar, the hind legs are already powerful enough to be studied for their jumping mechanics, which researchers have modeled as a torsional-spring system at the knee joint.
4PubMed Central. Impact of Different Developmental Instars on Locusta migratoria Jumping PerformanceHow Crowding Flips the Switch
The defining feature of a locust, as opposed to an ordinary grasshopper, is its ability to switch between two dramatically different behavioral states. In the solitary phase, nymphs are cryptic, avoid one another, and eat conservatively. In the gregarious phase, they actively seek each other out, form dense marching bands, and become voracious. Many grasshopper species share bits of this color and behavior plasticity: a phylogenetic analysis of one major subfamily found that the capacity for phase-like color change evolved multiple times and that the underlying physiological machinery is ancient rather than a recent innovation.
5PubMed. Phylogeny of bird-grasshopper subfamily Cyrtacanthacridinae (Orthoptera: Acrididae) and the evolution of locust phase polyphenismWhat triggers the switch in individual nymphs? The answer is surprisingly specific. Researchers systematically stimulated eleven different body regions on solitary desert locust nymphs and found that only one produced a significant shift toward gregarious behavior: the outer surface of the hind leg. Touching other body parts did nothing. The conclusion is that when environmental conditions concentrate solitary locusts into a smaller area, repeated bumping against one another’s hind legs is the sensory event that seeds swarming behavior.
6PubMed Central. Gregarious behavior in desert locusts is evoked by touching their back legsEarly work on the neurochemistry of phase change pointed to serotonin as a key player, but the picture has grown more complicated. Injecting serotonin directly into solitary desert locust nymphs did not trigger the expected behavioral shift or color change in at least one careful study, suggesting the pathway is more nuanced than a single neurotransmitter flipping a switch.
7PubMed. Behavioral phase shift in nymphs of the desert locust, Schistocerca gregaria: special attention to attraction/avoidance behaviors and the role of serotoninChemical Signals That Pull Nymphs Together
Once a few nymphs begin transitioning toward the gregarious phase, chemical signals accelerate the process. Nymphs of crowded desert locusts aggregate strongly in response to volatile chemicals released from their own feces and from the feces of young adults, though they ignore volatiles from older adult droppings.
8PubMed. Fecal volatiles as part of the aggregation pheromone complex of the desert locust, Schistocerca gregaria (Forskal) (Orthoptera: Acrididae)A more recently identified compound, 4-vinylanisole (4VA), acts through a specific olfactory receptor called OR35. Modeling work shows that when this receptor is functional, 4VA-driven attraction helps nymphs cluster together during the early, chemically driven phase of gregarization, especially when visual contact is limited. If a large proportion of individuals lack functional OR35, spatial clustering breaks down and the swarm fails to coalesce. Once visual sensing takes over at higher densities, the chemical signal matters less.
9Ecological Modelling. Modeling and analysis of locust hoppers dynamics under olfactory receptor 35 deficiencyGut bacteria also contribute to the chemical ecology. Bacteria living in and on locusts have been shown to participate in producing some of the attractant volatiles that help hold swarms together, adding a microbial dimension to the aggregation puzzle.
10PubMed. Locust Bacterial Symbionts: An UpdateColor, Shape, and the Power of Sight
Gregarious nymphs look strikingly different from solitary ones. Desert locust nymphs at low densities show a green or brown coloring that blends into vegetation and soil. At high densities they develop bold black patterning on a yellow or orange background, making them conspicuous.
11PubMed. The mechanism controlling phenotypic plasticity of body color in the desert locust: some recent progressWhat’s remarkable is that this transformation does not require physical contact. In an experiment where a single solitary nymph was placed in a cup where it could see other locusts in an adjacent cup but never touch them, the visual stimulus alone was enough to induce black patterning. The more locusts the isolated nymph could see, the darker it became. When it could see five or ten neighbors, its body proportions also shifted: the ratio of hind femur length to head width moved toward values typical of fully gregarious individuals.
12PubMed. Do desert locust hoppers develop gregarious characteristics by watching a video?The hormonal side of this color change involves at least two players. Both juvenile hormone and a neuropeptide called corazonin are needed for nymphs to express the green coloration of the solitary phase.
13Applied Entomology and Zoology. Corazonin and locust phase polyphenism When corazonin was injected into isolated-reared migratory locust nymphs, their body proportions shifted toward the gregarious form, the first demonstration that this peptide affects not just color but overall body shape.
14Journal of Insect Physiology. The dark-color inducing neuropeptide, [His7]-corazonin, causes a shift in morphometic characteristics towards the gregarious phase in isolated-reared (solitarious) Locusta migratoriaMarching Bands, Cannibalism, and Thermoregulation
Before they can fly, gregarious nymphs travel in dense marching bands that can stretch for kilometers across open ground. These bands move with an eerie coordination that looks organized from above but is driven by a less elegant mechanism: cannibalism. Nymphs in a marching band tend to bite those around them and risk being bitten themselves. When researchers surgically reduced nymphs’ ability to sense others approaching from behind, individuals were less likely to start moving, the proportion of moving locusts in the group dropped dramatically, and cannibalism increased. Blocking the rear visual field had a similar dampening effect. The picture that emerges is one of a “forced march” where each locust keeps moving partly to avoid being eaten by the one behind it, creating an autocatalytic feedback loop that sustains the band’s forward motion.
15PubMed. Collective motion and cannibalism in locust migratory bandsTemperature is the other major governor of marching activity. In the South American migratory locust, hopper body temperatures exceeded air temperature in the morning as the nymphs basked and group-basked before beginning to move. Sustained marching occurred at body temperatures near 40°C. When ground temperatures exceeded 50°C, nymphs switched to thermoregulatory behaviors: jumping, “stilting” (standing tall on extended legs to lift the body off the hot ground), seeking shade, or perching on vegetation.
16PubMed. Band movement and thermoregulation in Schistocerca cancellataHow Diet Changes with Phase
Solitary and gregarious nymphs do not just look different; they eat differently. Solitary nymphs are picky eaters. When offered food containing the plant alkaloid hyoscyamine, solitary nymphs rejected it and had shorter feeding bouts on first contact. Gregarious nymphs, by contrast, ate the alkaloid-containing food as readily as the control diet, showing no discrimination at all. Nymphs in a transitional state between solitary and gregarious actually preferred the alkaloid-laced food.
17Journal of Orthoptera Research. Diet breadth and anti-predator strategies in desert locusts and other OrthopteransThis broadening of diet makes ecological sense. A marching band of millions of nymphs cannot afford to be selective; they strip the landscape of whatever vegetation is available. But it comes at a cost when the food itself is toxic or nutritionally poor. When locusts were fed artificial diets containing elevated zinc concentrations, they ate more slowly on the high-zinc food, took longer to complete the fourth instar, and gained less body mass even though total food consumption stayed roughly the same.
18Functional Ecology. Metal hyperaccumulation in plants: mechanisms of defence against insect herbivoresMothers Shape the Next Generation
Phase is not just determined by a nymph’s own experience. Female desert locusts adjust the developmental trajectory of their offspring based on how much crowding the mother herself has experienced. A mother who has been crowded produces offspring that are smaller, come from larger clutches (more eggs per pod), and are more likely to hatch with dark, gregarious-type coloring. When isolated females were exposed to crowded conditions by housing them with just four males, they produced smaller clutches of larger eggs and fewer green hatchlings.
19PubMed. Epigenetic transmission of phase in the desert locust, Schistocerca gregaria: determining the stage sensitive to crowding for the maternal determination of progeny characteristicsThe mother appears to encode a kind of memory of both how recently and how intensely she was crowded, and this memory gets written into the eggs she produces. The result is that swarm conditions can be transmitted across generations even before the hatchlings encounter a single neighbor.
20PubMed. Maternal effects on phase characteristics in the desert locust, Schistocerca gregaria: a review of current understandingControlling Hoppers Before They Get Wings
From a pest management perspective, the hopper stage is the most critical window for intervention. Wingless nymphs are confined to the ground, concentrated in bands, and not yet capable of the hundred-kilometer daily flights that make adult swarms so devastating. Kill them now or face a flying army later.
One widely used tool is diflubenzuron, an insect growth regulator that disrupts the formation of chitin, the structural component of the exoskeleton. When nymphs ingest diflubenzuron, the next molt goes catastrophically wrong: the new cuticle fails to form properly, leading to death, physical deformities like lost limbs, lethargy, and cessation of feeding.
21Journal of Orthoptera Research. A literature review and new observations on the use of diflubenzuron for control of locusts and grasshoppers throughout the worldThe appeal of growth regulators over broad-spectrum insecticides is that they are more targeted. Because they act on the molting process, they primarily affect immature insects and have a lower immediate impact on organisms that do not molt. The downside is timing: the insecticide has to be applied and ingested before the next molt, and it does not kill adults that have already completed their final molt. This makes surveillance and early detection of hopper bands critical. Once the hoppers fledge into adults and take flight, the control window has closed.
Locusts as Food
For all the damage locust hopper bands inflict on crops, humans in many cultures have turned the equation around and eaten the locusts themselves. This is not just a survival strategy. Locust powder is rich in protein, essential amino acids, minerals, and polyunsaturated fatty acids. Safety testing in rats found no signs of acute toxicity even at doses of 20 grams per kilogram of body weight, and sub-chronic feeding trials lasting up to 90 days at dietary concentrations of 1 and 3 percent locust powder showed no significant biochemical or blood-related toxic effects.
22PubMed. Nutritional and safety evaluation of locust (Caelifera) powder as a novel food materialHarvesting locusts for food also raises an interesting ecological tension. In regions where locust swarms periodically devastate agriculture, the same insects represent an abundant, freely available protein source. Traditional harvesting methods, including netting hopper bands at dawn when they are still cold and sluggish, take advantage of the very thermoregulatory behavior that makes bands stationary in the early morning. Whether large-scale locust harvesting could ever serve as a meaningful form of population control alongside its nutritional benefits remains an open question, but the nutritional profile alone makes a strong case for not letting all that protein go to waste.