How Do Froghoppers Jump So High?
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Froghoppers, also called spittle bugs, are true bugs, and they are among the strongest jumpers in the animal kingdom. The question of how do froghoppers jump so high has a short answer: their hind legs are launched by a catapult-like elastic mechanism rather than by muscle power alone. Slow muscle contraction loads springy parts of the thorax, and those parts then release the energy suddenly. This article explains each stage, the parts involved, and what the research sources do not settle.
Quick answer
- The BMC Biology paper calls the froghopper “The fastest of the insect jumpers” and says it “uses a catapult-like elastic mechanism.”
- Muscles load the springs slowly: “energy, generated by the slow contraction of muscles, is released suddenly to power rapid and synchronous movements of the hind legs.”
- Most of the stored energy sits in the hard cuticle: “the energy storage is primarily in the chitinous cuticle of the pleural arches,” while the resilin itself “could only store 1% to 2% of the energy required for jumping.”
What makes a froghopper a champion jumper
The eLife paper places froghoppers among the best jumpers in insects. It states that “The champion jumping insects, as judged by their take-off velocities, all use a catapult mechanism and belong to two groups of the true bugs (Hemiptera), the closely related planthoppers (Fulgoroidea) and froghoppers or spittle bugs (Cercopoidea).” The same paper gives the scale of the effort: “They achieve these remarkable velocities by accelerating their bodies in about 1 ms and in so doing experience forces that can reach 700 g; most humans pass out with forces 100 times less.”
Timing matters as much as force. The BMC Biology paper explains the basic limit on muscle output: “A muscle can either contract rapidly and generate limited energy, or it can contract slowly to generate its maximal energy.” It adds that “The balance between these two extremes sets a functional limit to the amount of power (energy/time) that a muscle can generate.”
The two-stage energy budget
The eLife abstract describes the sequence in two stages. First, “Energy to power jumping was generated by slow contractions of hind leg depressor muscles and then stored by bending specialised elements of the thoracic skeleton.” Second, “The energy is then released suddenly, by mechanisms that are not yet fully understood, to generate rapid propulsive movements of the hind legs.”
The BMC Biology authors state the general principle in one sentence: “Animals that use movements demanding both high speed and power have to overcome these limitations by slowly deforming elastic structures to maximise the energy stored, and then deliver this stored energy by rapid recoil.” The froghopper follows the same pattern. Muscles work slowly to bend parts of the skeleton, and those parts then return the energy quickly.
The same principle appears in other arthropods. The BMC Biology paper says: “Arthropods often use deformation of their exoskeleton as an elastic energy store, particularly when generating fast and powerful predatory strikes or when jumping.”
Where the energy is stored
The BMC Biology paper locates the key movement: “The key movements of the hind legs of froghoppers in jumping occur at the joints between the coxae and trochantera.” It then names the driving muscles: “The depression movements of the trochantera that propel a jump are generated by a pair of large and complex depressor muscles, each of which consists of four parts.” These muscles provide the slow loading phase described above.
The stored energy sits in the pleural arches. The BMC Biology paper says that “Thus, the pleural arches associated with the hind legs appear to be possible sites where energy could be stored for jumping in froghoppers.” The eLife paper describes what happens before a jump: the paired trochanteral depressor muscles “contract before a jump but the hind legs remain stationary in their fully cocked (levated) positions.” The next step bends the arches: “This action pulls on the trochantera with the result that the pleural arches are bent and their curvature increased.”
Release follows that loading. As the jump is released, “the pleural arches unfurl and both coxae move backwards rapidly as a unit.”
Why resilin matters, and why it is not the main store
Resilin is a rubber-like protein inside the composite structure. The BMC Biology paper describes its molecular build: “Resilin consists of coiled peptide chains linked together in a stable, isotropic, three-dimensional network by the fluorescent amino acids, dityrosine and trityrosine.” It also says that “Resilin is mechanically highly deformable and shows almost perfect elastic recovery.”
The division of labour is stated directly: “Muscle contractions bend the chitinous cuticle with little deformation and therefore, store the energy needed for jumping, while the resilin rapidly returns its stored energy and thus restores the body to its original shape after a jump and allows repeated jumping.”
The paper concludes that “The composite structure therefore, combines the stiffness of the chitinous cuticle with the elasticity of resilin.” The energy numbers support that split. “Calculations showed that the resilin itself could only store 1% to 2% of the energy required for jumping.” By contrast, “The stiffer cuticular parts of the pleural arches could, however, easily meet all the energy storage needs.”
Locusts show a related design in a different structure. The BMC Biology paper says: “Locusts jump rapidly and powerfully by co-contracting the flexor and extensor tibiae muscles of their enlarged hind legs for a sustained period.” In the same passage, “Approximately 50% of the required energy is stored by bending two cuticular semi-lunar processes at the femoro-tibial joint of each hind leg.”
How the two legs are synchronised
The mechanism needs both hind legs to move together. The BMC Biology paper describes the froghopper’s movement as “rapid and synchronous movements of the hind legs.” The eLife paper explains what happens without that timing: “Without this synchrony, the body will spin with little accompanying forward movement, as much of the mechanical energy acts to rotate the body.”
Predictability matters as well. The eLife paper says that “The insects must also ensure that the starting point for the movements is always the same so that they can perform jumps with predictable outcomes.” Before each jump, the legs are set in place: “Before a jump, the hind legs are moved into their fully levated position so that the coxae are located anteriorly within the metathorax.”
The pre-jump loading does not move the legs. In the eLife paper’s words, “The large trochanteral depressor muscles then contract without moving the hind legs, resulting in the pleural arches being bent.” The legs stay put while the spring is charged, and then the release sends them forward.
Scale of the movement
The BMC Biology paper compares a stimulated movement with a natural one. Stimulating one muscle “results in a distortion and forward movement of the posterior part of a pleural arch by 40 μm, but in natural jumping, the movement is at least 100 μm.” The natural movement is therefore at least two and a half times the stimulated one.
The eLife paper adds a structural point about the energy path. It describes the three parts it studied as the core of the jump, and it poses a question about the mechanics: “how do the muscles and their mechanical advantages change during jumping movements?” Its answer on the lever arm is that “The images showed that the lever arm of the power-producing muscle changed in magnitude during jumping, but at all joint angles would cause depression, suggesting a mechanism by which the stored energy is released.”
Why nymphs do not jump
The nymphs make a useful contrast. The eLife paper says: “By contrast, the nymphs of froghoppers do not jump and instead live a rather restricted life either underground, or on plant leaves, surrounding themselves with a protective froth which they make by blowing air into their urine.”
The resilin signal also differs between stages. The BMC Biology paper says “No other structures in the thorax or hind legs show this blue fluorescence and it is not found in larvae which do not jump.”
How researchers see the resilin
Resilin is colourless to the eye but can be seen under the right light. The BMC Biology paper says: “Resilin is colourless but can be revealed by exploiting its fluorescent properties accorded to it by its two tyrosine components.” The paper also notes that “Dityrosine, trityrosine and resilin each emit a uniform blue fluorescence when excited by ultraviolet (UV) light.”
The BMC Biology paper states that the froghopper’s structures are “built of chitinous cuticle and the rubber-like protein, resilin, which fluoresces bright blue when illuminated with ultra-violet light.”
What the 3D scans added
The eLife study used imaging to map the jumping hardware. Its authors wrote that they “reconstructed from confocal scans the 3-D structure of three elements of the jumping mechanism to address three questions.” The first question asks about the stored energy: “what is the structure of the thorax that enables the energy generated by the muscle contractions to be stored and power a jump?”
The eLife paper also compares several species. It reports that the authors “analysed different species of planthoppers and froghoppers to seek common features or differences in” their jumping structures. The broader point is that the catapult design is shared across the two groups, which is why the paper treats them together.
For a related topic on insects and plants, see how to attract native bees, or the wider guide to attracting pollinators to a garden.
How we chose
The two sources are peer-reviewed research articles from PubMed Central. Burrows and colleagues published “Resilin and chitinous cuticle form a composite structure for energy storage in jumping by froghopper insects” in BMC Biology in 2008. Siwanowicz and Burrows published “Three dimensional reconstruction of energy stores for jumping in planthoppers and froghoppers from confocal laser scanning microscopy” in eLife in 2017. Neither source is a retail page, and every claim in this article is tied to a quote from one of them.
What we could not verify
Two research papers cover the mechanism, so the points below rest on those two papers alone.
What the sources do not say
The release step is not fully explained. The eLife paper says the energy is released “by mechanisms that are not yet fully understood.” The explanation of the sudden release therefore stays open in these sources.
The sources also give only part of the energy budget. The BMC Biology paper quantifies the resilin share as “1% to 2%,” and it reports that the cuticle “could, however, easily meet all the energy storage needs.” Neither source adds a single full breakdown of how muscle work, cuticle storage and resilin storage add up for one jump.
The sources do not give one number for every froghopper species. The eLife paper studied “different species of planthoppers and froghoppers,” so its figures describe the species it examined, not the whole group.
Frequently asked questions
How fast do froghoppers take off?
The eLife paper says froghoppers achieve their velocities “by accelerating their bodies in about 1 ms.” The source gives take-off speeds only for their best jumps, so no single speed applies to every jump.
Do froghopper nymphs jump?
No. The eLife paper says “the nymphs of froghoppers do not jump,” and the BMC Biology paper says the blue fluorescence “is not found in larvae which do not jump.”
Is resilin the main energy store?
No, according to the BMC Biology paper. It says “the energy storage is primarily in the chitinous cuticle of the pleural arches,” and that “the resilin itself could only store 1% to 2% of the energy required for jumping.”
What is resilin?
The BMC Biology paper describes it as “the rubber-like protein,” built from “coiled peptide chains linked together in a stable, isotropic, three-dimensional network” with a high degree of elastic recovery.
Why do both hind legs have to move together?
The eLife paper explains that “Without this synchrony, the body will spin with little accompanying forward movement, as much of the mechanical energy acts to rotate the body.”
Sources
- Burrows M, Shaw SR, Sutton GP. “Resilin and chitinous cuticle form a composite structure for energy storage in jumping by froghopper insects.” BMC Biology. 2008. https://pmc.ncbi.nlm.nih.gov/articles/PMC2584104/
- Siwanowicz I, Burrows M. “Three dimensional reconstruction of energy stores for jumping in planthoppers and froghoppers from confocal laser scanning microscopy.” eLife. 2017. https://pmc.ncbi.nlm.nih.gov/articles/PMC5479696/
