Migratory grasshoppers are notorious agricultural pests capable of causing widespread crop damage, especially during outbreak years. These insects can travel long distances in search of food, consuming vast amounts of vegetation along the way.
While grasshoppers are a natural part of many ecosystems, population surges can lead to severe economic losses for farmers. Factors such as drought and favorable breeding conditions often contribute to outbreaks.
The High-Plains Nomad: Migratory Grasshoppers
The Migratory Grasshopper (Melanoplus sanguinipes) is arguably the most economically significant grasshopper species in North America. While many grasshoppers stay within a small radius of their hatching ground, this species is built for distance. During “outbreak years,” they can form massive swarms that travel hundreds of miles, devastating rangelands, wheat fields, and vegetable gardens across the Great Plains and the Western United States.
The “Generalist” Appetite
What makes the Migratory Grasshopper particularly dangerous is its lack of a specific host plant. They are true generalists that will consume almost any green vegetation in their path. Their feeding habits include:
- Defoliation: They consume the leaf tissue of cereal grains, alfalfa, and clover, often leaving only the toughest stems behind.
- Head Clipping: In wheat and barley, they are known to chew through the stem just below the grain head, causing the entire crop to drop to the ground before it can be harvested.
- Vegetable Shredding: In home gardens, they can decimate leafy greens, tomatoes, and even onions in a matter of hours during a peak migration.
Identification and the “Spine”
The Migratory Grasshopper is a medium-sized, brownish-yellow insect. To the untrained eye, it looks like many other “spur-throated” grasshoppers. However, it can be identified by the small, pointed prosternal spine between its front legs and the distinct black bands on its hind femurs. Their wings are long and powerful, extending well beyond the tip of the abdomen, which facilitates their long-distance flight.
U.S. Agricultural Management
In the U.S., large-scale management is often coordinated through RAATs (Reduced Agent and Area Treatments). This strategy involves spraying only strips of land, allowing the grasshoppers’ natural predators (like birds and robber flies) to survive in the untreated areas and help control the population. For the individual landowner, management strategies include:
- Tillage: Fall or early spring tilling can destroy the egg pods buried in the soil.
- Nosema locustae: A biological control (fungal spore) that infects and weakens grasshoppers without harming beneficial insects or mammals.
- Floating Row Covers: In garden settings, heavy-duty mesh is the only reliable physical barrier when a swarm arrives.
Identification
Grasshoppers are medium-sized insects with strong hind legs adapted for jumping. They vary in color but are often green or brown, allowing them to blend into vegetation.
Life Cycle
Eggs are laid in soil during late summer and hatch in spring. Nymphs resemble smaller versions of adults and gradually develop wings through successive molts.
Damage
Grasshoppers consume leaves, stems, and crops, often stripping plants bare. In large numbers, they can devastate entire fields.
Control
Control includes habitat management, biological controls such as fungal pathogens, and targeted insecticide use during early nymph stages.