Grasshoppers are often simplified as mere "grass-eaters," but this description barely scratches the surface of one of the most successful and ancient groups of herbivorous insects on Earth. Belonging to the suborder Caelifera, these insects have been refining their dietary habits for approximately 250 million years, dating back to the early Triassic period. Understanding what grasshoppers eat requires looking beyond the blades of grass in a backyard and examining a complex world of botanical preferences, opportunistic scavenging, and specialized digestive mechanics.

While most of the 11,000 known species are predominantly phytophagous—meaning they feed on plant matter—their menu is remarkably broad. From cereal crops and garden vegetables to toxic weeds and even the occasional bit of animal matter, the grasshopper diet is a testament to their evolutionary resilience.

The Anatomy of an Ancient Chewer

To understand what grasshoppers eat, one must first look at how they eat. Grasshoppers possess a highly specialized chewing mouth apparatus that has remained largely unchanged for millions of years. Unlike insects with piercing-sucking mouthparts (like aphids or mosquitoes), grasshoppers are built for mechanical destruction.

Their mouth consists of several key structures: the mandibles, the maxillae, and the labrum. The mandibles are strong, tooth-like jaws that move horizontally to grind and cut through tough plant fibers. For many species, the shape of these mandibles varies depending on their primary food source; those that eat tough grasses often have blunter, more molar-like grinding surfaces, while those feeding on soft-leaved forbs (broadleaf plants) have sharper, more incisor-like edges.

Before the food even enters the mouth, grasshoppers use the taste buds located on their antennae and palps to receive chemical information about the plant's quality and toxicity. Once consumed, the food follows a specific path through a sophisticated digestive system. It first enters the crop, a storage organ where initial breakdown begins. From there, it moves to the gizzard, which uses muscular contractions and internal teeth to further pulverize the plant matter. The process continues through the gastric caeca and stomach, where enzymes extract nutrients before water is reabsorbed in the rectum. This efficient system allows some species to consume their own body weight in vegetation every single day.

Primary Food Sources: The Green Menu

The majority of grasshoppers are polyphagous, meaning they can utilize a wide variety of plant species. However, their preferences are rarely random. Their diet generally focuses on several key categories:

Grasses and Sedges

For many members of the subfamily Gomphocerinae, grasses are not just a preference but a requirement. These insects are common in rangelands and prairies, where they feed on native bunchgrasses and introduced turf. They are particularly fond of the tender, nitrogen-rich new growth that appears after rain. In agricultural settings, this translates to a love for cereals like wheat, barley, oats, and rye.

Forbs and Broadleaf Plants

Many grasshoppers, particularly those in the subfamily Melanoplinae (the spur-throated grasshoppers), prefer forbs over grasses. These are non-woody flowering plants that often contain higher levels of protein and water than dried grasses. Sunflowers, clover, alfalfa, and various legumes are highly relished. In garden environments, this is why they are often seen decimate lettuce, beans, and even the leaves of fruit trees.

Crops and Vegetables

When grasshopper populations reach high densities, they transition from natural vegetation to high-value agricultural crops. They are known to gnaw on the foliage of corn, soybeans, and peanuts. In some cases, they don't stop at the leaves; they may chew on immature pods, fruit skins, or even the bark of young twigs, leading to "girdling" wounds that can kill the branch.

Species-Specific Preferences

Not all grasshoppers eat the same things. In regions like the North American Great Plains, researchers have identified distinct dietary niches among the hundreds of coexisting species.

  • The Migratory Grasshopper (Melanoplus sanguinipes): This is one of the most versatile eaters. While it prefers weedy forbs, wheat, and barley, it is notoriously opportunistic. If its preferred green food vanishes, it will scavenge on ground litter, dried manure, or even dead insects to survive.
  • The Two-Striped Grasshopper (Melanoplus bivittatus): Often found in gardens and suburban settings, this species has a broader palate that includes trees and shrubs. It is particularly fond of legumes and sunflowers and is frequently the culprit behind damaged backyard vegetable patches.
  • The Clear-winged Grasshopper (Camnula pellucida): This species is a grass specialist. It rarely touches forbs or broadleaf plants, focusing almost exclusively on native and introduced grasses. This makes it a significant pest for cattle ranchers who rely on healthy pastureland.
  • The Differential Grasshopper (Melanoplus differentialis): This large species is commonly found in lush, moist areas. It is a major consumer of corn and ragweed, showing a high tolerance for plants that other insects might avoid.

The Surprising Side of the Diet: Scavenging and Cannibalism

While we categorize them as herbivores, many grasshoppers are technically omnivorous when conditions demand it. This behavior is often driven by a need for specific nutrients, particularly protein and salt, which may be lacking in a purely plant-based diet during drought periods.

Scavenging

It is not uncommon to see grasshoppers feeding on dead insects, including other grasshoppers. They are also known to consume animal feces (manure), which provides a concentrated source of nitrogen and minerals. This scavenging behavior is more prevalent in the later stages of their life cycle when they are producing eggs and require higher nutritional intake.

Cannibalism

In extreme cases, particularly during swarming events or severe food shortages, grasshoppers may turn on each other. If an individual is weakened, molting, or injured, its neighbors may seize the opportunity for a high-protein meal. This "forced" change in diet helps the population survive when the landscape has been stripped bare of every green leaf.

How Do Grasshoppers Drink?

One of the most frequent questions regarding grasshopper biology is whether they need a water source. In nature, grasshoppers rarely drink standing water from puddles or dewdrops. Instead, they obtain nearly all their hydration from the plants they consume.

Succulent leaves and grasses are often composed of 80% to 90% water. By consuming large quantities of this vegetation, the grasshopper remains sufficiently hydrated. This is why grasshopper populations tend to congregate in "greenbelts" or irrigated gardens during dry summers; the plants in these areas have higher water content, providing both food and moisture in one package. When a grasshopper is observed near a humid or marshy area, it is usually because the vegetation there is more nutritious and easier to digest, not necessarily because the insect is looking for a drink.

Factors Influencing Food Choice

A grasshopper’s diet is not static; it changes based on internal and external factors.

Life Cycle Stages

Nymphs, or "hoppers," have smaller mandibles and a more limited range of movement. They tend to stay close to where they hatched—usually in undisturbed, weedy areas like roadsides or fence rows. Their diet consists of tender young shoots that are easy to chew. As they undergo their five molts and grow larger, their diet expands to include tougher stalks and a wider variety of plant species.

Seasonal Availability

In early spring, grasshoppers focus on cool-season grasses and emerging weeds. As the summer progresses and these plants begin to dry out, the insects migrate toward late-blooming forbs and agricultural crops. In the fall, their feeding slows down as they focus on mating and egg-laying, but they may still consume dried plant litter to maintain energy levels.

Climate and Environment

Weather plays a significant role in what and how much grasshoppers eat. Warm, dry weather increases their metabolic rate, making them more voracious. Conversely, cool and wet weather can slow their digestion and make them more susceptible to fungal diseases that thrive in high humidity. In some ecological zones, grasshoppers even act as beneficial insects by consuming toxic weeds that would otherwise be harmful to livestock.

The Impact of Grasshopper Feeding on Ecosystems

While they are often viewed as pests, grasshoppers are vital components of their ecosystems. By consuming vast amounts of plant matter, they speed up the process of nutrient cycling. Their waste (frass) returns nitrogen and other minerals to the soil in a form that plants can easily reabsorb.

Furthermore, because they eat such a wide range of plants, they help prevent any single plant species from dominating an area, thereby promoting biodiversity. They are also a primary food source for a vast array of predators, including birds, spiders, rodents, and other insects. The energy they extract from plants is passed up the food chain, supporting the entire local wildlife population.

Identifying Grasshopper Damage in the Garden

For gardeners, recognizing what a grasshopper has been eating is the first step in management. Unlike the clean cuts of a caterpillar or the small holes of a beetle, grasshopper damage is usually characterized by large, ragged chew marks starting from the edge of the leaf and moving inward. In severe cases, they may leave only the central midrib of the leaf intact.

They are particularly attracted to gardens that are well-watered when the surrounding natural vegetation has turned brown. They are less fond of nitrogen-fixing plants like peas or sweet clover, often preferring to move past these in search of more succulent greens like lettuce or corn. Some gardeners have noted that they avoid plants with strong odors, such as garlic, which has led to the development of garlic-based repellents, though the effectiveness of these varies depending on the grasshopper species and the hunger level of the population.

Summary of the Grasshopper Diet

In essence, a grasshopper is a biological machine designed to convert plant biomass into energy with incredible efficiency. Their diet is a sophisticated balance of:

  1. Selection: Using sensory palps to find the most nutritious leaves.
  2. Mechanical Processing: Grinding tough fibers with specialized mandibles.
  3. Opportunism: Supplementing their diet with protein from scavenging when necessary.
  4. Hydration: Extracting every drop of moisture from the plants they consume.

Whether they are feeding on a single blade of prairie grass or a row of prize-winning vegetables, grasshoppers remain one of the most significant herbivores on the planet. Their ability to eat almost any green thing is why they have survived for 250 million years and why they continue to be a subject of fascination and frustration for humans today. Understanding the nuances of what they eat—and why—allows us to better appreciate their role in the natural world, even as we work to protect our crops from their impressive appetites.