Las Vegas Grasshopper Invasion: Causes, Impacts, and Lessons from an Unusual Swarm
An in-depth look at the 2019 Las Vegas grasshopper invasion, exploring its environmental origins, community impact, and what it can teach us about urban ecology.
In the summer of 2019, Las Vegas experienced an event that seemed almost apocalyptic: enormous swarms of grasshoppers descended on the city, filling the air, plastering buildings, and blocking out neon lights famous worldwide. While grasshopper swarms are hardly new to the Western United States, the scale, location, and timing of the 2019 Las Vegas invasion made it a unique ecological phenomenon—as well as a captivating mystery to scientists and the public alike.
Grasshoppers in Las Vegas: The Spectacle Unfolds
Residents and visitors to Las Vegas in July 2019 witnessed a mass migration of pallid-winged grasshoppers so dense that their bodies appeared as clouds over the famous Strip. Locals described the city as being under insect siege: grasshoppers swarmed through the air at night, drawn to the city’s ultraviolet-rich lights, splattering windshields, clogging doorways, and leaving thick carpets of insect remains.
- Hotels and casinos turned off some signs to avoid attracting more bugs
- Neon-lit attractions reportedly disappeared behind waves of insects
- Many tourists and residents were surprised, disgusted, or amazed by the sudden presence of so many grasshoppers
The event was so dramatic it made international headlines, with many likening the scenes to a biblical plague—except this one posed no threat to human health or safety, only inconvenience and awe.
Understanding the Swarm: What Caused the 2019 Invasion?
The sudden explosion of grasshoppers prompted scientists to dig deeper into what caused this extraordinary event. In reality, a combination of ecological and climatic factors converged to bring about this migration.
A Perfect Storm of Weather and Ecology
- Wet Winters: The 2018–2019 winter in Nevada was unusually wet and cool. Abundant rainfall promoted explosive growth of desert vegetation, offering food and habitat for grasshopper nymphs.
- Rapid Plant Growth: Lush springtime growth provided grasshoppers ample food during early development, resulting in higher survival rates and greater population density.
- Dry Summer: As spring turned to summer, the desert vegetation started to dry out, forcing grasshoppers to look for greener plants and new food sources—often found in urban areas with irrigated vegetation.
- Attraction to Urban Lights: Pallid-winged grasshoppers are highly attracted to bright, ultraviolet lights—and Las Vegas boasts some of the world’s most dazzling and UV-rich displays.
Why Las Vegas?
The widespread use of UV-spectrum lighting in Las Vegas’s outdoor signage and architecture acted as a magnet for grasshoppers. When these insects took flight during their migration, they naturally gravitated toward the brightest sources, clustering in swarms around the downtown and the Strip.
| Contributing Factor | Description | Local Effect |
|---|---|---|
| Increased Rainfall | Wet winter led to lush plant growth | More grasshopper eggs survived |
| Drying Desert | Vegetation dried, insects searched for new food | Grasshoppers moved into the city |
| Vegas City Lights | High intensity and UV light attracted swarming insects | Mass congregations downtown and on the Strip |
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Impact on the City: Inconvenience, Wonder, and Ecological Lessons
While the Las Vegas grasshopper invasion was visually spectacular and often a nuisance, it barely impacted public health or safety. The bugs did not bite, sting, or transmit disease, and they left just as abruptly as they had arrived.
Community and Tourist Reactions
- Nuisance Factor: Masses of grasshoppers forced some businesses to turn off outdoor lights, regularly clean up dead insects, and address customer complaints about unpleasant encounters.
- Media Sensation: The event became a viral topic, with videos and images shared across social media and mainstream news, some exaggerating the threat and danger.
- Scientific Curiosity: Many scientists and educators saw the event as a rare opportunity to discuss desert ecology, insect migrations, and the effects of human-altered landscapes on wildlife.
How Long Did the Grasshoppers Stay?
The invasion was short-lived. Experts, such as state entomologist Jeff Knight, explained that these kinds of grasshopper explosions typically last only a couple of weeks. The bugs were seeking food and were temporarily drawn in by city lights, but would soon either die off or migrate onward as conditions changed. There is generally only one generation per year for these grasshoppers, which further limits how long they persist in such numbers.
Ecological Impact: More Than a Nuisance?
Despite the drama, grasshoppers posed no real threat to the city’s infrastructure, agriculture, or native wildlife. Their biggest impact was as a seasonal food resource for local predators, such as birds, reptiles, and small mammals, who benefited greatly from the sudden bounty.
- The grasshoppers did some limited damage to backyard gardens and turf, including golf courses, especially at the city’s edges.
- Pets and humans were generally unaffected, though pets that ingested large quantities of bugs could experience mild digestive issues.
- Wildlife, including coyotes, foxes, and birds, enjoyed a boost in available insect protein.
Entomologists also highlighted that urban ecosystems often put people in closer contact with natural events like insect migrations, especially when city designs incorporate enticing features, such as bright nighttime lighting and lush landscaping.
The Science of Desert Insect Swarms
Events like the Las Vegas grasshopper invasion are not unique in the Earth’s history, but their manifestation in modern urban settings is increasingly visible due to the ways human development attracts and concentrates mobile species.
Natural Boom-and-Bust
- Desert insects display cyclical population explosions following favorable weather, especially wet periods that enable mass hatching and juvenile survival.
- When food becomes scarce or habitat overcrowded, many grasshoppers and related insects enter a migratory phase, flying en masse to new areas.
Urban Influence on Swarms
- Cities offer persistent green areas, watered lawns, and gardens that serve as food oases for migrating insects.
- Bright, UV-rich artificial lighting attracts nocturnal and crepuscular (twilight-active) insects from miles around.
The intersection of natural insect population cycles and the specific features of Las Vegas’s urban landscape produced 2019’s extraordinary spectacle.
Why Do Grasshoppers Swarm?
Most grasshoppers are not normally gregarious, but certain environmental triggers, such as crowding, scarcity of resources, and suitable weather, can cause them to form large migratory groups. These swarming behaviors serve several functions:
- Enable escape from depleted habitats
- Increase access to new food sources
- Facilitate mating by bringing individuals together
Unlike the infamous desert locust swarms of Africa and Asia—which devastate crops and threaten food security—North American grasshopper swarms like those seen in Las Vegas rarely last long or cause major agricultural destruction.
Lessons Learned: Living with Nature in a Changing Climate
While the Las Vegas grasshopper invasion faded after a few weeks, it left behind key lessons for urban planners, residents, and environmentalists.
- Preparedness: Understanding how unusual weather can create opportunities for sudden wildlife events is essential. By keeping track of seasonal insect patterns and drivers—especially in rapidly changing climates—cities can improve readiness for odd but harmless natural surges.
- Sustainable Lighting: The event highlighted the power of artificial lighting not just in drawing insects but in influencing animal behavior more broadly. Shifting to less UV-intensive lighting or using motion sensors may reduce unwanted insect congregations and conserve energy.
- Appreciation for Biodiversity: Rather than viewing the invasion solely as a nuisance, scientists and some citizens saw an opportunity to appreciate wildlife events as reminders of our coexistence with nature—even in places as urbanized as Las Vegas.
How to Respond to Future Invasions
No chemical controls or large-scale eradication were deployed, as grasshoppers didn’t pose a real danger and were destined to leave on their own. Local advice for residents included:
- Turn off unnecessary outdoor lights to reduce attraction
- Seal windows and doors to limit entry into buildings
- Tolerate or clean up the harmless insects as needed, understanding the event would not last
Frequently Asked Questions (FAQs)
Are grasshopper invasions like this dangerous?
No. Grasshoppers in these swarms typically do not bite, sting, or carry disease.
They are considered harmless to humans, pets, and structures.
How long do grasshopper invasions usually last?
Usually only a couple weeks. Once the environmental triggers subside (less city light activity, more food out of town, lifecycle progression), the swarm dissipates.
Are grasshoppers attracted to any kind of lights?
They are mostly attracted to bright lights, especially those rich in ultraviolet (UV) wavelengths. Classic Las Vegas signage, loaded with UV, is particularly alluring to them.
Do grasshopper swarms happen every year?
No. These events tend to be cyclical, driven by unusual weather patterns. Years with especially wet winters followed by hot, dry summers make them more likely, but such conditions are rare.
What benefits, if any, do grasshopper invasions bring?
They provide a valuable food source for local wildlife, contribute to nutrient cycling, and can help control certain invasive weeds through their feeding.
Conclusion: Embracing the Surprise of Nature
The sudden grasshopper invasion of Las Vegas in 2019 was a vivid example of how natural cycles and human environments can intersect in surprising ways. Although disruptive in the short term, the event offered a rare chance for scientific observation and public fascination. As unusual weather becomes more common with climate change and cities continue to expand, similar spectacles—and the lessons they offer—may become part of the urban experience for communities far beyond Las Vegas.
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