Cicadas and locusts are distinct insect species, often confused due to their periodic large-scale appearances and the sounds they produce. Despite common misconceptions, these insects belong to different biological classifications and exhibit unique characteristics. Understanding their differences clarifies their roles in ecosystems and dispels long-standing inaccuracies.
Not the Same: A Clear Distinction
Cicadas and locusts are not the same insect. They belong to entirely different scientific orders. Cicadas are classified under the order Hemiptera, which includes “true bugs” like aphids and leafhoppers. In contrast, locusts are a type of grasshopper, falling within the order Orthoptera.
This taxonomic difference means they are as unrelated as a butterfly is to a beetle. While both can emerge in large numbers and create considerable noise, their biological makeup and life strategies set them apart.
How Cicadas and Locusts Differ
Cicadas and locusts display numerous distinguishing features in their diet, life cycles, sound production, physical appearance, and behaviors. These differences highlight their unique adaptations and ecological impacts.
Cicadas primarily feed on plant fluids using piercing-sucking mouthparts. Nymphs feed on root fluids underground, while adults consume sap from twigs and woody shrubs. In contrast, locusts are herbivores with chewing mouthparts, consuming leaves and other plant tissue above ground.
Cicadas are known for their prolonged nymphal stage, spending years underground, often 13 or 17 years for periodical cicadas. During this time, they develop through multiple instars. After emerging as adults, cicadas typically live for only a few weeks to a couple of months.
Locusts have a shorter, more direct life cycle involving egg, nymph (hopper), and adult stages. Their lifespan is typically a few months to less than a year, with nymphs developing through five to six instars over 4 to 8 weeks.
Male cicadas produce loud, distinct songs using specialized organs called tymbals. These membranes vibrate rapidly, creating a continuous buzzing or singing sound, amplified by their hollow abdomen. This sound attracts mates, and some cicada species can produce sounds exceeding 100 decibels.
Locusts generate sound through stridulation, rubbing body parts together. This produces softer chirping or buzzing sounds for communication and mate attraction.
Physically, cicadas have stocky bodies, measuring ¾ to 1½ inches long, with prominent eyes, often bright red in periodical cicadas. They possess two pairs of clear, membranous wings, held tent-like over their bodies. Locusts have more slender bodies, measuring 1 to 2 inches, with large hind legs adapted for jumping. Their wings are leathery forewings protecting delicate hind wings, and their eyes are brown or green.
Behaviorally, cicadas are not considered agricultural pests; their feeding on tree sap causes minimal harm to mature trees. They emerge in large numbers, synchronously, but they do not swarm. Locusts, however, are known for forming destructive swarms, consisting of billions of individuals, traveling long distances and devastating crops. A single locust swarm can consume hundreds of tons of vegetation daily, a threat to food security and agriculture.
Understanding the Misconception
The common confusion between cicadas and locusts stems from historical misidentification and linguistic overlap. Early European settlers encountered periodical cicadas emerging in massive numbers, reminiscent of biblical plagues. They often mislabeled the cicadas as “locusts,” a term for destructive swarms.
Biblical references to “locusts” describe a type of grasshopper known for voracious appetite and crop devastation. This reinforced the association of large insect populations with the term “locust.” For instance, the “seventeen-year locust” is a historical misnomer for periodical cicadas. This inaccurate terminology persisted through generations. The sheer number and loud emergence of cicadas simply evoked the destructive, swarming behavior of true locusts.