Locusts vs Cicadas: Distinct Insects with Very Different Stories

Locusts and Cicadas: Understanding the Differences

Locusts and cicadas are two familiar, buzzing insects that often confuse lay observers. Although they look similar at a glance and both belong to the order Hemiptera, they are unrelated groups with striking differences in life cycles, behavior, and impact on ecosystems and humans. These differences are crucial for understanding their roles in nature and the potential implications for agriculture and biodiversity.

What They Are and Where They Fit

• Cicadas belong to the superfamily Cicadoidea within the order Hemiptera. They are best known for their loud mating calls and long underground nymph stages, with several species exhibiting periodic emergences every 13 or 17 years in some regions. This unique life cycle allows them to synchronize their emergence, creating a spectacle that attracts attention. Cicadas play roles as herbivores and prey for a variety of predators, and they can provide nutrient pulses to ecosystems when they emerge in large numbers. This nutrient influx can significantly benefit soil health and plant growth in the areas they inhabit.

• Locusts are a phase of certain grasshopper species (order Orthoptera) under environmental triggers that cause a dramatic change from solitary to gregarious, swarming behavior. Locust swarms can be vast and destructive, traveling long distances and consuming substantial amounts of vegetation, which has direct implications for agriculture and livelihoods in affected regions. These swarms can lead to severe food shortages and economic distress, particularly in regions that rely heavily on agriculture for sustenance and income.

Key Differences in Appearance and Life Cycles

• Appearance: Cicadas typically have stout bodies, prominent eyes, clear-veined wings, and a characteristically robust, buzzing presence. Their distinctive appearance makes them easily recognizable during the warmer months. Locusts resemble grasshoppers with more elongated bodies, strong hind legs for jumping, and wing forms that vary between species and seasonal phases. This adaptability in appearance allows locusts to thrive in various environments and conditions.

• Life cycle: Cicadas spend most of their lives underground as nymphs, feeding on sap from plant roots, before tunneling to the surface to molt into winged adults. The adult window can be brief but intensely active, centered on mating and egg-laying. This brief period is crucial for the continuation of their species. Locusts have nymphal stages that resemble miniature grasshoppers; under certain conditions, populations can breed rapidly, mature in weeks, and form swarms that march across landscapes. This rapid life cycle enables them to respond quickly to favorable environmental conditions.

Behavior and Ecological Impact

• Mating and communication: Cicadas produce loud, species-specific calls using specialized organs on the abdomen to attract mates. These calls can be so powerful and widespread that they drown out other sounds during peak emergence. This auditory display is vital for successful reproduction. Locusts communicate and maintain swarm cohesion through various signals, including sound production and density-dependent behaviors that synchronize movement and feeding. This communication is essential for the survival of swarming locusts as it helps them coordinate their actions during migrations.

• Ecological role and risk to humans: Cicadas mainly affect trees and shrubs by feeding on xylem and phloem juices; while heavy feeding can cause branch dieback, cicadas are not typically agricultural pests on a continental scale. Their role in ecosystems is generally beneficial, as they contribute to nutrient cycling. Locust swarms pose significant agricultural threats, capable of decimating crops and pastures, leading to food security concerns and economic losses in affected regions. The potential for locusts to cause widespread devastation necessitates careful monitoring and management strategies.

Common Misconceptions Clarified

• Not all loud insects are cicadas, and not all swarming insects are locusts. The term “locust” is a behavioral phase rather than a taxonomic group, while cicadas are a distinct lineage with a unique life history that includes long subterranean development. Understanding these distinctions helps clarify their ecological roles.

• Periodic cicadas are celebrated for their synchronized emergences and are a natural phenomenon rather than an agricultural menace, whereas locust outbreaks are feared for their potential to devastate farmland in a matter of weeks. This difference in perception is important for public awareness and education regarding these insects.

Illustrative Examples

• Periodical cicadas in North America emerge in massive broods after 13 or 17 years, providing a burst of biomass that supports predators and enriches soil with their exuviae after they molt to adults. This phenomenon creates a unique ecological event that benefits various species in the ecosystem.

• Desert locust swarms in parts of Africa and the Middle East can number in the billions when conditions align, moving across continents and consuming crops and grasses in their path. The sheer scale of these swarms can lead to humanitarian crises in the regions affected.

Why Understanding the Distinction Matters

• For gardeners and homeowners, cicadas are generally a temporary, seasonal presence with limited long-term damage, while recognizing locust swarms helps communities prepare for possible agricultural impacts and coordinate management strategies with authorities. This knowledge can be crucial for crop planning and pest management.

• For educators and students, the contrast between cicada life cycles and locust swarming behavior provides a clear case study in how climate, weather, and ecosystem structure influence insect population dynamics. This understanding can foster greater appreciation for biodiversity and the complexities of ecological interactions.

Quick Reference at a Glance

For readers seeking deeper dives, consult authoritative field guides on Hemiptera and Orthoptera, agricultural extension resources on locust management, and entomology texts that explain cicada life cycles and periodicity. These resources can provide valuable insights into the fascinating world of these insects and their ecological significance.