Are Grasshoppers Omnivores? Diet Range, Gut Limits, and Crop Impact

Yes, grasshoppers are omnivores, but nearly all of them are omnivores at the margins. Roughly 12,000 described species in the suborder Caelifera build their bodies from plant tissue, and most generalists also eat animal matter when they encounter it: insect eggs, carrion, dung, and dead or weakened grasshoppers. A few species scavenge habitually, and locusts turn cannibalistic when crowded. The label is accurate but imprecise, because proportions decide the ecology. For most grasshoppers, meat is a supplement measured in single-digit percentages, not a staple.

Diet Range: Are Grasshoppers Omnivores or Mostly Herbivores?

An animal counts as omnivorous when it feeds at more than one trophic level, and grasshoppers clear that bar easily. Crop dissections, gut smears, and DNA metabarcoding of gut contents routinely turn up animal material beside plant fragments. The proportions swing enormously between species and between seasons.

In generalist pest species such as the migratory grasshopper, Melanoplus sanguinipes, plant tissue typically makes up 90 percent or more of intake by mass. Animal matter appears in most samples at low single-digit percentages, rising after rain, during crowding, or when foliage quality drops. Habitual scavengers such as the horse lubber, Taeniopoda eques, run far higher, with reported animal shares reaching a third or more of gut contents in some populations. No grasshopper is a strict carnivore; obligate meat-eating has never been documented in Caelifera.

Diet breadth follows the same spectrum. A mixed generalist may sample 30 to 50 plant species across a season, switching as nitrogen content changes. A specialist may eat one or two. That flexibility is the real story behind grasshopper omnivory, because it lets a population persist when its preferred host senesces.

Those shares are rough literature ranges, not fixed constants, because sampling methods differ and soft tissue digests faster than cuticle. In plain terms: a grasshopper is a plant eater that keeps a standing invitation to eat meat.

Gut Limits: Mouthparts, pH, and Protein Balance

The anatomy explains both why omnivory is possible and why it stays capped. Grasshopper mouthparts are built for shearing and grinding, not for killing. Paired mandibles carry incisor cusps that cut and molar cusps that crush, and they work sideways like scissors. They handle grass blades, seed heads, and thin insect cuticle well. They are poor tools for subduing anything that can run.

Behind the mouth, the tract is a fast pipeline rather than a fermentation vat. A crop stores food, a chitinous proventriculus grinds it, and the midgut absorbs it with help from six pairs of gastric caeca. The midgut sits near neutral to mildly alkaline, around pH 7 to 8. Roughly 100 to 250 Malpighian tubules handle waste and water balance.

Cellulose digestion sets the ceiling. Grasshoppers produce their own cellulase, a rare trick among insects, but the enzyme is an endoglucanase that cannot fully break crystalline cellulose. Hindgut microbes help, yet net digestibility of cellulose lands near 30 to 50 percent. Food therefore moves through in roughly 4 to 12 hours, and the insect must keep eating almost continuously.

The body weight figure makes the pressure concrete. A late-instar nymph or adult eats roughly 0.8 to 2 times its own body weight in fresh foliage each day. Mature grass carries only about 8 to 12 percent protein by dry mass, while insect carcasses run near 60 percent. That gap is why a grasshopper that finds a dead cricket has found a protein concentrate.

Regulation of protein against carbohydrate ties the whole system together. Work using the geometric framework, developed by Stephen Simpson and David Raubenheimer, shows grasshoppers defend an intake target and adjust feeding when nutrients drift. Foliage grown at elevated carbon dioxide, around 600 to 800 parts per million, often carries 10 to 15 percent less protein per gram. Grasshoppers respond by eating more, and in some conditions by taking more animal matter.

Sodium adds a second non-obvious driver. Inland foliage can hold under 0.05 percent sodium by dry mass, while animal tissue holds roughly an order of magnitude more. Field experiments led by Michael Kaspari in the 2010s found that grasshoppers on low-sodium soils ate more insect prey, and grew faster where sodium was added. In plain terms: meat is a protein and mineral supplement that becomes worth chasing when plants are dilute.

Crop Impact: Consumption Rates and Thresholds

Because intake is high and continuous, moderate densities translate into real forage loss. Reported losses on infested rangeland acres during outbreak years run 20 to 50 percent of available forage. That figure is why managers count insects instead of waiting for visible defoliation.

The density thresholds used in the western United States are the same number expressed for different land values. The USDA Animal and Plant Health Inspection Service treats 8 grasshoppers per square yard as the action point where forage is valuable, 16 per square yard on moderate pasture, and 30 or more per square yard where control costs exceed the forage at risk. The three figures differ because the economics differ, not because the biology changes.

Field crops get less tolerance. Seedlings of wheat, barley, and alfalfa can be clipped at the soil line before they establish, so any density that threatens a stand matters more than the rangeland numbers suggest. Grasshoppers also feed on developing soybean and pulse pods, which turns a leaf-level nuisance into a yield problem. Margins, ditch banks, and headlands are the usual invasion routes into a field.

Locust swarms scale the arithmetic into a different category. Densities can reach 80 million insects per square kilometer, roughly 200 million per square mile. A swarm of about 40 million desert locusts eats as much food in one day as 35,000 people, per the Food and Agriculture Organization. The largest swarms strip on the order of 100,000 metric tons of vegetation daily.

A rough comparison makes the individual numbers tangible. One million adult grasshoppers weigh about 1,000 to 2,000 pounds. If each eats its body weight in fresh foliage daily, and fresh foliage is roughly 25 percent dry matter, that population removes 250 to 500 pounds of dry forage daily. A mature cow eats about 25 pounds of dry matter daily, so the swarm matches 10 to 20 cows. This is arithmetic, not a field measurement, but it shows why thresholds sit in the single digits per square yard.

The Outbreak Timeline: From Egg Pod to Swarm

The time course matters for control, because each stage has a different vulnerability. Development speeds up with heat, so the ranges below assume warm soil and air at roughly 77 to 86 degrees Fahrenheit. Cooler conditions stretch every row.

Misconceptions That Persist About Grasshopper Diets

The most common error is treating locusts as a separate kind of animal. Locusts are grasshoppers in the family Acrididae, and the desert locust is a grasshopper that switches phase under crowding. Solitary and gregarious forms differ in color, shape, and behavior, not in species.

The second error involves Mormon crickets. They swarm, they scavenge animal matter, and they are frequently blamed on grasshoppers, but they belong to the katydid family Tettigoniidae. Records that mix the two inflate how carnivorous grasshoppers appear.

A third misconception assumes omnivory implies hunting. Most animal matter taken by grasshoppers is already dead: roadkill fragments, dried insects, dung, egg masses, and injured nymphs. Active pursuit of healthy prey is rare and mostly limited to crowding conditions.

People also assume grasshoppers have a termite-style fermentation chamber. They do not. Their strategy is rapid passage and high volume, which is why they favor young, nitrogen-rich growth over mature stems. Finally, the pest label is applied far too broadly: a few dozen species cause nearly all economic damage, while thousands of others never reach a density worth noticing.

What to Actually Do

Scout before treating. Take 10 to 20 sweep-net sweeps at five to ten points across a field, or use a square-foot frame on rangeland, and record nymphs separately from adults. Nymphs in the second to fourth instar are the most cost-effective target, because they cannot fly and consume less before control begins.

Protect the enemies you already have. Robber flies, ground beetles, spiders, birds, and blister beetle larvae all take grasshoppers or their eggs. Leaving a 3 to 5 foot unmowed border and avoiding unnecessary tillage keeps those populations in place. Adult blister beetles are also pollinators, so identification matters before any spray decision.

Use pathogens where the label allows. The microsporidian Nosema locustae is registered in the United States for grasshopper nymphs and works slowly, over weeks. Metarhizium acridum products are registered in parts of Africa and Australia for locust control but not in the United States. Both fail in cool weather, so timing matters more than dose.

Reduce egg-laying habitat in fall. Tall, undisturbed grass and firm soil are preferred oviposition sites, so mowing or light surface disturbance in late summer lowers next spring's hatch. Row cover on seedlings buys time in gardens where chemical control is undesirable.

• Do not spray broad-spectrum insecticide during bloom, or on days with wind above about 10 miles per hour.
• Do not treat rangeland below the threshold for your forage value, whether that is 8, 16, or 30 grasshoppers per square yard.
• Do not expect a single application to stop a gregarious locust swarm, which can reinvade within days.
• Do not rely on Nosema locustae as a knock-down; it acts over weeks, not hours.
• Do not wipe out blister beetles, robber flies, or spiders while treating grasshoppers.

Limits of the Evidence That Remain

Diet data are thin relative to the diversity involved. Intensive feeding studies exist for a small fraction of the roughly 12,000 described grasshopper species, and most of those studies come from agricultural pests in North America and Europe. Tropical and desert species are badly underrepresented.

Method bias cuts in a predictable direction. Soft animal tissue digests quickly, so gut content analysis undercounts meat, while tough plant cuticle persists and overstates plant material. DNA metabarcoding detects more animal DNA but quantifies it poorly, and it can pick up prey DNA from inside a consumed predator.

Laboratory trials inflate carnivory potential. A caged grasshopper will eat meat it could never catch in the field, and the absence of predators removes the cost of foraging in the open. Field estimates are lower for that reason.

The sodium and carbon dioxide links are promising but not settled. Sodium-driven omnivory has experimental support in a handful of systems, and protein dilution under elevated carbon dioxide varies with plant species and nitrogen supply. Both are active research areas, not established rules. In plain terms: the omnivore label is solid, but the exact share of meat in a wild grasshopper's diet remains an estimate with wide error bars.