Colorado Grasshoppers: Snap, Crackle, and Hop
Amazingly Diverse Colorado Grasshoppers
By Eric R Eaton:
As is the case with many categories of insects, grasshoppers suffer from the bad reputation of a few species. The vast majority are of little or no consequence to gardens, pasture, and range, while feeding countless other organisms. Their behavior can be literally colorful and loud.
Grasshoppers are defined here as those species described as “short-horned grasshoppers” for their short antennae, excluding the long-horned katydids and crickets. There are roughly 145 species in Colorado, ranging from pygmy grasshoppers in the family Tetrigidae, to the flightless heavyweight known as the Plains Lubber or “Homesteader,” in the family Romaleidae. Most grasshoppers are in the family Acrididae.
Band-winged grasshoppers are the most conspicuous, at least when flying. Yes, most grasshoppers have wings as adults, and either glide or fly. The Carolina Grasshopper is so well camouflaged that even when you know where one is sitting it is nearly impossible to see. Then it takes off. Broad black hindwings explode into view. The insect may easily be mistaken for a butterfly. Then it lands and disappears as the flying wings are folded like Japanese fans beneath the cryptic forewings.
Male band-winged locusts may perform flight displays for females. The Carolina grasshopper hovers. Most others flash their yellow, orange, red, or even blue hindwings in a noisy display called crepitation. How they generate the snapping or crackling sounds is still a mystery. Some species, like the Wrangler Grasshopper, found at higher elevations on scree, sustain their crepitation for a lengthy period, sounding like a secretary on a manual typewriter.
Males also display to each other in ground-based dances of dominance. Femur-tipping involves lifting the hind leg suddenly, exposing a pattern of black and white bands on the inside surface, and a hind tibia that may be yellow, bright orange, blue, or greenish.
Being cold-blooded, grasshoppers must regulate their body temperature behaviorally. In the cool morning, a grasshopper will bask by leaning into the sun and dropping its hind leg to expose its abdomen fully to the warming rays. By afternoon, the same insect is standing on tiptoe, maybe even lifting its feet alternately to avoid scorching on the hot sand, rocks, or soil.
Grasshoppers go through simple metamorphosis, immature stages resembling miniature adults but lacking a reproductive system, and wings in those species with winged adults. Female grasshoppers, after mating, deposit egg pods in the soil, telescoping their abdomens to reach deep into the ground. This is still the most vulnerable stage in the life cycle, as other insects, and vertebrate animals, can make a living on grasshopper eggs.
A case in point is the cautionary tale of the Rocky Mountain Locust, Melanoplus spretus. As colonialism spread westward, settlers encountered this insect in massive numbers. Swarms in 1874 and 1875 represent the greatest concentration of insects ever recorded in human history. The permanent home of the grasshopper was the intermountain valleys of Wyoming and northern Colorado. With the Gold Rush pushing settlements into this region, plowing for agriculture dug up the egg pods of the grasshopper. In a matter of a few years, there were no longer swarms dispersing to both sides of the Continental Divide. By 1902, the Rocky Mountain Locust was extinct. The whole, captivating story is told in the gripping book Locust, by Jeffrey Lockwood.
Locusts are not separate insects, but a special form of grasshopper that has deviated from a normally solitary phase. Triggered by crowding as nymphs, literally rubbing knees with each other, kentromorphism causes their bodies to metamorphose differently, eventually producing longer-winged adults that continue to be gregarious. These are the “teeth of the wind” found mostly in Africa, the Middle East, and southern Europe. Local weather patterns favorable to locust irruptions may or may not become more frequent with climate change. This applies to the general abundance or absence of grasshoppers in Colorado, too, where drier years usually mean more grasshoppers.
It may come as a shock to learn that grasshoppers are omnivores. They feed on their own road-killed dead, prey upon injured insects, and otherwise scavenge animal matter in addition to their usual consumption of plants. Many species are generalist feeders, but a few prefer broad-leaved plants to grasses, or specialize even more within the forbs category.
A surprising discovery was revealed recently. Grasshoppers in some places are not receiving certain key micronutrients in sufficient amounts to reproduce at a normal, healthy rate. Increasing levels of carbon dioxide in the atmosphere make plants grow faster, but the tradeoff is that levels of phosphorus, nitrogen, potassium, and sodium decrease.
It may be difficult to resist the urge to spray for grasshoppers on your property, but know that natural forces will eventually intervene; and we forget the capacity of (native) plants to rebound after defoliation. Remember that a healthy prairie, meadow, range, or yard has a good diversity of insects that snap, crackle, and hop.
Eric R. Eaton is principal author of the Kaufman Field Guide to Insects of North America and writes the blog “Bug Eric.”