Cicadas and locusts are often confused, particularly when large numbers of insects emerge. Despite some superficial similarities, these insects are distinct, belonging to entirely different scientific classifications and exhibiting unique biological characteristics, life cycles, and behaviors. This common misconception stems partly from historical misnomers.
Understanding Cicadas
Cicadas are insects classified within the order Hemiptera, commonly known as “true bugs.” They primarily feed on plant fluids, with nymphs consuming xylem from plant roots underground and adults feeding on sap from young tree twigs. Cicadas do not chew leaves or destroy crops.
Their life cycle involves incomplete metamorphosis, progressing through egg, nymph, and adult stages. Cicada nymphs spend a considerable portion of their lives, from two to five years for annual species and up to 13 or 17 years for periodical cicadas, developing underground. Once mature, they emerge for a brief adult stage, typically lasting only a few weeks to reproduce. Male cicadas produce their characteristic loud sounds using specialized structures called tymbals, which are ribbed membranes on their abdomen that vibrate rapidly to attract mates. While their mass emergences can be striking, cicadas generally cause minimal damage, mostly limited to slight twig injury from egg-laying in young trees.
Understanding Locusts
Locusts are a type of grasshopper belonging to the order Orthoptera. These insects are known for their voracious appetites, consuming large quantities of vegetation, often including agricultural crops. Their life cycle involves incomplete metamorphosis, passing through egg, nymph, and adult stages, but their overall lifespan is much shorter, typically lasting only weeks to a few months for adults. Eggs are laid in the soil, and wingless nymphs emerge, molting several times before reaching adulthood.
A defining characteristic of locusts is their ability to undergo “phase polyphenism,” a transformation from a solitary existence to a gregarious, swarming form. This behavioral change is often triggered by specific environmental conditions, such as increased population density following periods of prolonged dry weather broken by rain, which leads to abundant vegetation. When these conditions are met, locusts aggregate into massive, migratory swarms that can cause widespread devastation to agricultural lands and natural ecosystems. This destructive swarming behavior sets them apart from most other grasshoppers.
Key Differences
The distinctions between cicadas and locusts begin with their taxonomic classification. Cicadas are members of the order Hemiptera, often referred to as “true bugs,” characterized by their piercing-sucking mouthparts. In contrast, locusts are a specific type of grasshopper within the order Orthoptera, known for their chewing mouthparts and powerful hind legs adapted for jumping. This means they are not closely related insects.
Their feeding habits also vary significantly. Cicadas feed on tree sap and root fluids, causing minimal damage. Locusts, however, are highly destructive herbivores that consume entire plants and crops. The method of sound production is another clear differentiator; male cicadas produce loud calls using specialized tymbals, while locusts create quieter chirping sounds through stridulation, rubbing their legs against their wings.
Behaviorally, cicadas emerge periodically in large numbers as a synchronized emergence rather than a migratory swarm. Locusts, conversely, form highly mobile and destructive swarms that migrate across vast regions. Their life cycles also differ; cicadas have prolonged nymphal stages lasting years underground, followed by a short adult life, whereas locusts have much shorter lifespans and reproduce rapidly. Physically, cicadas generally possess stout bodies, large, wide-set eyes, and clear, membranous wings. Locusts tend to have more slender, elongated bodies, prominent hind legs for jumping, and shorter antennae. The common confusion between these two insects, particularly in North America, often stems from early European settlers mistakenly calling periodical cicadas “locusts” due to their sudden, large-scale appearances, which evoked biblical accounts of locust plagues.