Grasshoppers are overwhelmingly herbivores, but calling them strict herbivores would be wrong. The vast majority of their diet consists of plant material, and their mouthparts, gut bacteria, and detoxification chemistry are all built around processing leaves, stems, and grasses. Yet researchers have repeatedly documented grasshoppers scavenging dead insects, feeding on mammal carcasses, and even cannibalizing each other. The honest label for many species is “primarily herbivorous with opportunistic omnivory,” a feeding strategy that turns out to be far more sophisticated than simply munching whatever greenery is nearby.
Plants Are the Foundation
As a group, grasshoppers in the family Acrididae range from species that eat only one or two plant types to broad generalists that feed on dozens. Most fall somewhere in between, eating a moderate variety of plants rather than being truly picky or truly indiscriminate.1PubMed. Feeding patterns in grasshoppers (Orthoptera: Acrididae): Factors influencing diet specialization Within that range, evolutionary lineage matters. Grasshoppers in the subfamily Gomphocerinae lean heavily toward grasses, while those in the Melanoplinae prefer broadleaf plants called forbs, and the band-winged grasshoppers of the Oedipodinae show less clear-cut preferences.1PubMed. Feeding patterns in grasshoppers (Orthoptera: Acrididae): Factors influencing diet specialization
Their protein and amino acid needs are met primarily by soluble leaf protein, much like other chewing, plant-eating insects.2ScienceDirect. Nutrition and the protein economy in grasshoppers and locusts This is worth noting because it means grasshoppers do not need animal protein the way truly omnivorous insects do. Plants supply what they require under normal conditions, and the entire digestive system is tuned to that reality.
When Grasshoppers Eat Other Animals
Despite being built for a plant diet, many grasshopper species will readily eat dead insects, including other grasshoppers. In experiments in southwestern Montana, researchers placed grasshopper carcasses in the field and watched how quickly live grasshoppers found them. At one site, grasshoppers began feeding on the cadavers within an average of five minutes. At a second site, the average was just under fourteen minutes.3Environmental Entomology. Scavenging Behavior of Grasshoppers (Orthoptera: Acrididae): Feeding and Thermal Responses to Newly Available Resources That speed suggests grasshopper scavenging is not some rare, accidental behavior. These insects seem primed to take advantage of animal protein when it appears.
Some species go further. The horse lubber grasshopper, Taeniopoda eques, was documented feeding on the carcass of a mammal over multiple visits. Researchers observed one to eight adults on the body during each visit, with females far outnumbering males. The females were actively scraping dried tissue from bones, consuming hair and dried hide, and even entering the body cavity to feed inside it.4Journal of Orthoptera Research. Necrophagy in Grasshoppers: Taeniopoda eques Feeds on Mammal Carrion No other grasshopper species in the area were seen on the carcass, making this behavior appear species-specific rather than universal, but it demonstrates how far from “strict herbivore” some grasshoppers can stray.
Cannibalism Under Crowding
The most dramatic departure from herbivory occurs during locust swarms. Migratory locusts, which are essentially grasshoppers that shift into a swarming phase, engage in widespread cannibalism when populations are dense. This behavior is common enough that the locusts have evolved a chemical countermeasure: under crowded conditions, they produce a compound called phenylacetonitrile that deters other locusts from eating them. Both the rate of cannibalism and the amount of this anti-cannibalism pheromone scale with population density.5PubMed. A chemical defense deters cannibalism in migratory locusts
The existence of a dedicated chemical defense against being eaten by your own kind tells you that cannibalism is not a freak occurrence. It is frequent enough that natural selection has shaped a response. In locust biology, the fear of being eaten from behind by the individual marching next to you is thought to be one of the forces that keeps swarms moving forward. Individuals that stop or slow down get bitten. So while the label “herbivore” applies to a locust sitting alone in a field nibbling a grass blade, it barely captures what happens when millions of them converge.
Active Nutrient Balancing
One of the more striking findings about grasshopper feeding is that they do not just eat whatever they land on. They actively select foods to balance their intake of protein and carbohydrate. When offered a choice between synthetic foods with different nutrient ratios, both generalist and specialist grasshopper species composed a balanced diet, mixing the available options to hit a target ratio. The generalist species selected more protein than the grass specialist did, while carbohydrate intake was similar.6PubMed. Nutrient balancing in grasshoppers: behavioural and physiological correlates of dietary breadth
This balancing act extends to populations in the wild. Alaskan populations of the lesser migratory grasshopper, Melanoplus sanguinipes, consistently self-selected a diet centered on a protein-to-carbohydrate ratio of about 0.90.7Physiological Entomology. Discriminating tastes: self‐selection of macronutrients in two populations of grasshoppers When confined to a nutritionally imbalanced food with no alternatives, grasshoppers adjusted how much they ate to minimize both excesses and deficits.6PubMed. Nutrient balancing in grasshoppers: behavioural and physiological correlates of dietary breadth Even closely related grasshopper species living in the same habitat and eating the same plant species will consume protein and carbohydrate in different absolute amounts and ratios, occupying distinct nutritional niches.8PubMed Central. Coexisting generalist herbivores occupy unique nutritional feeding niches
This sophisticated nutrient regulation helps explain the scavenging behavior. If a grasshopper’s current plant diet is low in protein, a dead insect is a concentrated protein source. Rather than eating more low-quality plant material, a quick bite of a carcass can correct the balance. The scavenging is not random desperation; it fits into a broader strategy of nutrient management.
How They Digest All That Plant Material
Breaking down cellulose, the tough structural material in plant cell walls, is one of the hardest challenges for any herbivore. Grasshoppers appear to manage it through a combination of their own enzymes and help from gut bacteria, though the exact division of labor is still being worked out. Some Acrididae species produce their own cellulase enzymes capable of breaking down plant cell walls, but gut microbes clearly play a significant role as well.9PeerJ. Diversity of the gut microbiome in three grasshopper species using 16S rRNA and determination of cellulose digestibility
Studies of gut bacteria across multiple grasshopper species have found that specific bacterial groups correlate with how efficiently the grasshopper digests cellulose and hemicellulose. The bacterium Pantoea, for instance, showed a significant positive correlation with cellulose digestibility.10PubMed Central. Microbial gut diversity in four grasshopper species and its correlation with cellulose digestibility Other bacteria identified in grasshopper guts, including Corynebacterium, Glutamicibacter, and Clavibacter, have known abilities to hydrolyze hemicellulose or produce cellulase.9PeerJ. Diversity of the gut microbiome in three grasshopper species using 16S rRNA and determination of cellulose digestibility The picture that emerges is of a digestive system that relies on both intrinsic enzymes and a microbial community working together, though researchers note there is no direct evidence yet that grasshoppers depend entirely on gut microbes for cellulose breakdown.
The composition of these gut bacterial communities is influenced by both what the grasshopper eats and where it falls on the evolutionary tree. Feeding habit has a stronger effect than family-level taxonomy, but at broader taxonomic scales, evolutionary relationships dominate. Grasshoppers in the suborder Caelifera (short-horned grasshoppers) harbor gut communities that look distinctly different from those of Ensifera (crickets and katydids), even when the two groups eat similar diets.11PLOS ONE. Gut bacterial communities across 12 Ensifera (Orthoptera) at different feeding habits and its prediction for the insect with contrasting feeding habits
Coping with Plant Toxins
Plants do not passively accept being eaten. They produce a wide array of defensive chemicals, and grasshoppers that eat many different plant species need ways to handle that chemical barrage. When the grasshopper Oedaleus asiaticus was exposed to diets high in plant secondary compounds, it ramped up the activity of several key detoxification enzymes, including cytochrome P450s, glutathione-S-transferase, and carboxylesterase. The more toxic the diet, the higher the enzyme activity.12PubMed Central. Biology, physiology and gene expression of grasshopper Oedaleus asiaticus exposed to diet stress from plant secondary compounds These enzymes are part of a general-purpose detox toolkit shared across many insect groups, but their flexibility is what allows a generalist grasshopper to eat plants from multiple families without being poisoned.
Grasshoppers also use smell to evaluate potential food. Studies of three alpine grasshopper species in New Zealand found that their antennae were highly sensitive to fatty-acid-derived aldehydes and a specific alcohol, chemicals that plants release when they are damaged. All three species and both sexes responded similarly, with no species-specific preferences. The researchers suggested that these generalist grasshoppers may be tuning in to the smell of damaged plants in general rather than tracking down specific plant species by their unique scent.13Chemoecology. Food plant odor perception in three sympatric alpine grasshopper species (Orthoptera: Acrididae: Catantopinae) in Aotearoa New Zealand There is an interesting irony here: a plant’s wound signals, meant to recruit predators of herbivores or warn neighboring plants, may actually serve as a dinner bell for nearby grasshoppers.
How Rising CO2 Is Changing the Menu
As atmospheric carbon dioxide rises, plant chemistry shifts. Leaves grown under elevated CO2 tend to accumulate more carbon-based compounds (starches, structural fibers) while their nitrogen content drops. For a grasshopper, this means the food is getting bulkier and less nutritious. The expectation was that grasshoppers would simply eat more to compensate, but the reality is more complicated.
When Melanoplus sanguinipes was fed a C3 grass grown under elevated CO2, it did not significantly increase its consumption rate despite the lower nutritional quality. Instead, it appeared to use internal, post-ingestive mechanisms to maintain its growth rate.14PubMed. Performance of a generalist grasshopper on a C3 and a C4 grass: compensation for the effects of elevated CO2 on plant nutritional quality In other words, the grasshopper extracted what it needed more efficiently rather than just eating a bigger pile. A study on the alpine grasshopper Miramella alpina found that CO2-induced changes in leaf water, nitrogen, and starch content did alter feeding behavior, growth, and reproduction, and that males and females responded differently in their choice of which plant species to eat more of.15PubMed. Growth and reproduction of the alpine grasshopper Miramella alpina feeding on CO2-enriched dwarf shrubs at treeline
Plant defensive chemistry adds another wrinkle. When sagebrush was grown under different CO2 concentrations, leaf nitrogen declined as expected, but the presence of sagebrush’s chemical defenses limited how much grasshoppers could increase their feeding to compensate. Leaf nitrogen was a positive factor in grasshopper growth, yet compensatory consumption was apparently capped by plant toxins.16PubMed. Sagebrush and grasshopper responses to atmospheric carbon dioxide concentration The upshot is that climate change will not uniformly make grasshoppers eat more or less. The outcome depends on the specific plant, its defensive chemistry, and the grasshopper species involved.
Grasshoppers as Nutrient Recyclers
The sheer volume of plant material grasshoppers consume gives them an outsized role in nutrient cycling, especially in grassland ecosystems. Over a five-year experiment, grasshoppers sped up nitrogen cycling by changing both the amount and the decomposition rate of plant litter. The result was an increase in total plant abundance of up to roughly 18%, with the gains going disproportionately to plant species that compete well when nitrogen is more available.17PubMed Central. Insect herbivory accelerates nutrient cycling and increases plant production This is a counterintuitive finding: an herbivore eating plants actually increased overall plant production by speeding up the return of nutrients to the soil.
In nitrogen-limited grasslands, heavy grasshopper herbivory amplified the availability of nutrients belowground almost immediately, triggering intense competition between plants and soil microorganisms. That competition accelerated nitrogen cycling and effectively retained the extra carbon and nitrogen released by the herbivory, preventing nutrient loss from the system.18Ecosphere. Grasshopper herbivory immediately affects element cycling but not export rates in an N‐limited grassland system Grasshoppers are not just consumers in the ecosystem. Through their frass (excrement), their selective feeding that shifts plant community composition, and the partially chewed litter they leave behind, they function as accelerators of the nutrient cycle.
Why They Are Also Agricultural Pests
The same voracious, flexible herbivory that makes grasshoppers ecologically important also makes them devastating to crops. Acridid grasshoppers frequently damage millions of hectares of western rangeland and cropland in North America alone.19PubMed Central. Control of Pest Grasshoppers in North America Their generalist feeding habits mean they do not limit themselves to wild grasses when wheat, alfalfa, or other crops are available, and locust outbreaks in other parts of the world can strip entire regions of vegetation within days.
Control strategies have historically relied on broad-spectrum insecticides, but current research focuses on targeted bait formulations and biological control agents that might reduce collateral damage to other insects.19PubMed Central. Control of Pest Grasshoppers in North America The challenge is that grasshopper outbreaks tend to be episodic and geographically vast, making localized interventions hard to scale. Understanding what drives grasshoppers to shift from background-level feeding to crop-devastating densities remains one of the bigger open questions in pest entomology.
Mouthparts and the Question of Diet-Driven Evolution
You might expect that grasshoppers specializing on tough grasses would have evolved measurably different jaw mechanics from those that eat soft forbs, but the relationship is surprisingly weak. A study examining bite force transmission and mandible shape across grasshoppers, crickets, and their relatives found that dietary categories had a statistically significant relationship with jaw mechanics, but the explanatory power was very low.20Evolution. Bite force transmission and mandible shape in grasshoppers, crickets, and allies is not driven by dietary niches In plain terms, knowing what a grasshopper eats tells you very little about the shape or mechanical advantage of its jaws. Evolutionary relationships and body size explain the jaw differences better than feeding habits do.
This finding fits with the broader picture of grasshoppers as flexible feeders. Rather than evolving highly specialized mouthparts for a narrow diet, most grasshoppers retain a generalized chewing apparatus that works adequately on a range of food types. That generality is part of what allows them to shift between plant species, scavenge animal material when available, and adjust their diet in response to nutritional needs or environmental change. The hardware is versatile, and the sophistication lies in the software: the sensory systems, detoxification pathways, and nutrient-balancing behaviors that let a generalized set of jaws deal with a complicated and variable world.