Rocky Mountain Locust Identification Guide
Learn the identifying traits of the Rocky Mountain Locust, a historically famous swarming grasshopper with long wings and powerful jumping hind legs.
Read the full Rocky Mountain Locust encyclopedia entry →
Key Visual Features
The Rocky Mountain Locust was a type of short-horned grasshopper, typically 1 to 1.5 inches long, with a robust, streamlined body built for both jumping and sustained flight.
- Body: Medium-sized and sturdy, generally yellowish-brown to olive in color, with darker mottling along the back and sides that helped it blend into grassland vegetation.
- Wings: Long, narrow forewings extending well past the tip of the abdomen, paired with membranous hindwings used for strong, sustained flight during swarming phases.
- Hind legs: Large and muscular, adapted for powerful jumps, with the classic grasshopper leg shape featuring an enlarged femur.
- Antennae: Short and thickened compared to katydids or crickets, a hallmark of short-horned grasshoppers.
- Head: Broad with large compound eyes positioned to give a wide field of view.
Where and When You'd See It
Historically, the Rocky Mountain Locust inhabited grasslands and river valleys of the Rocky Mountain region and Great Plains of North America, breeding in mountain valleys and periodically forming enormous migratory swarms across the plains during the warmer months, roughly from late spring through summer. It is now considered extinct, with the last confirmed sightings in the early 20th century, so any grasshopper-like insect encountered today in this region would belong to a different, closely related species rather than the true Rocky Mountain Locust.
Similar-Looking Bugs
Because the species is extinct, modern identification relies on comparison with related grasshoppers:
- Migratory grasshopper – A closely related living species with a similar body shape and coloring, often used as the closest modern reference point.
- Differential grasshopper – Larger and heavier-bodied, with a herringbone pattern on the hind legs not present on the Rocky Mountain Locust.
- Two-striped grasshopper – Distinguished by pale stripes running down the back, a marking absent in the Rocky Mountain Locust's more mottled pattern.
- Common field grasshoppers – General short-horned grasshoppers share the overall body plan but vary in color pattern, wing length, and size.
Quick ID Checklist
- Medium-sized, yellowish-brown body with mottled markings
- Long forewings extending past the abdomen tip
- Short, thickened antennae typical of short-horned grasshoppers
- Large, muscular hind legs built for jumping
- Historically associated with massive swarming migrations across the Great Plains
Frequently asked questions
Can the Rocky Mountain Locust still be found today?
No, the species is considered extinct, with the last verified specimens collected in the early 1900s, so modern sightings are attributed to closely related grasshopper species.
How did the Rocky Mountain Locust differ from a typical grasshopper?
It shared the general short-horned grasshopper body plan, with mottled yellowish-brown coloring and thickened antennae, but was distinguished historically by its long flight wings and tendency to form massive migratory swarms.
What modern species is most often compared to the Rocky Mountain Locust?
The migratory grasshopper is considered its closest living relative and is often used as a visual reference for body shape and coloring.
What time of year were Rocky Mountain Locust swarms historically observed?
Swarms were most commonly reported during the late spring and summer months, when locusts migrated in large numbers from mountain breeding grounds onto the plains.