Am I hearing locusts or cicadas?

The intense, whirring drone filling the summer air often leaves people wondering if they are listening to the biblical scourge of locusts or the familiar seasonal chorus of cicadas. While both insects create significant noise, they are biologically distinct creatures whose presence signals very different things about the local ecosystem and the time of year. ^[2][10] Understanding the source of that sound requires looking past the volume and examining insect classification, physical characteristics, and typical behavior. ^[2]

# Sound Production

The most immediate confusion stems from the sheer volume these insects can generate. When you hear that characteristic, often deafening, buzzing sound during warm months, you are almost certainly listening to cicadas. ^[9][7] Male cicadas possess specialized organs called tymbals, which are ribbed membranes they rapidly vibrate using specialized muscles to produce their incredibly loud mating calls. ^[2] These sounds are designed to travel long distances to attract females. ^[2] Different species produce different sounds, ranging from a buzzing drone to a high-pitched whine. ^[9] For instance, some periodical cicadas produce sounds reaching close to 100 decibels. ^[8]

Locusts, which are certain migratory phases of specific grasshopper species, do make noise, but it's fundamentally different. ^[3] Locusts typically create sound through stridulation—rubbing body parts together, similar to crickets or common grasshoppers. ^[3] While this noise is audible, it generally lacks the sustained, overwhelming intensity associated with a massive cicada emergence. ^[3] If the noise sounds like a sustained, electrical hum or a deafening, vibrating roar that seems to come from the trees themselves, the culprit is the true bug, the cicada. ^[7][9] The sheer scale of a cicada emergence, sometimes involving billions of insects, amplifies this sound far beyond what a typical locust field-chirp would achieve. ^[5]

# Noise Purpose

It is interesting to observe why these sounds are made. The cicada's noise is overwhelmingly focused on reproduction; it is a declaration of readiness to mate. ^[2] Conversely, while locusts might vocalize, their primary destructive fame comes from their feeding and migratory behavior rather than an auditory display designed to saturate the airwaves. When evaluating the sound, consider the context: if it is peak summer and the sound is constant and booming, the goal is propagation, pointing directly to cicadas. ^[2][9]

# Insect Classification

The most crucial difference between a locust and a cicada lies in their scientific classification, which dictates almost everything about their life and behavior. ^[2][10]

Cicadas belong to the order Hemiptera, commonly known as "true bugs," which also includes aphids and leafhoppers. ^[2][10] A key feature of true bugs is their mouthpart structure—they possess piercing-sucking mouthparts used to feed on plant fluids, specifically xylem. ^[2]

Locusts, however, are members of the order Orthoptera, the same order as crickets and regular, non-swarming grasshoppers. ^[2][10] Locusts are characterized by their strong hind legs built for jumping and chewing mouthparts. ^[2]

This taxonomic division means they are not just different species; they are fundamentally different kinds of insects. ^[10]

Where are locusts found in the US?

# Physical Traits

Telling them apart visually is straightforward once you know what to look for, assuming you spot one outside of a swarm or emergence hole.

Cicadas generally possess:

• Large, prominent eyes set wide apart on the head. ^[2]
• Four membranous wings that are usually clear, though they may have darker veins. ^[2]
• Stout, robust bodies. ^[2]

Locusts look exactly like the grasshoppers they are, meaning they have:

• Eyes that are closer together relative to their body size. ^[2]
• Hind legs adapted for powerful jumping. ^[2]
• Bodies that are built more for leaping than for the lumbering, tree-clinging behavior of a newly emerged cicada.

If you see an insect sitting on a tree trunk making a loud noise but using its feet to cling rather than its legs to spring away when approached, you are dealing with a cicada. ^[2]

# Life Cycle Contrast

Their life cycles are dramatically different, especially concerning their underground phase.

Cicadas are famous for their long, subterranean nymph stages. ^[2] Depending on the species, these can be 13 or 17 years for periodical broods, emerging all at once in massive numbers to mate and die within a few weeks. ^[5] Annual cicadas emerge every year, but their nymph period is still several years long. ^[2] This long, synchronized emergence is what causes those massive, highly noticeable events in areas like Massachusetts. ^[5]

Locusts, being grasshoppers, do not have such extended, synchronized underground phases. While they have nymph stages, they typically mature much faster, often within a single growing season. ^[2] The characteristic "locust" behavior—swarming—is a density-dependent change in behavior and morphology (phase polyphenism) triggered by crowding, turning them from solitary grasshoppers into gregarious, migratory pests that devour vegetation. ^[2][10]

Where are locusts in the world?

# Ecological Impact

The ecological roles, and the resulting impact on human activity, are usually the final differentiators in a reader's mind.

Cicadas are overwhelmingly beneficial or benign. While the sheer number of newly emerged adults can stress young or otherwise unhealthy trees by causing leaf wilting due to feeding on xylem fluid, established, healthy trees generally suffer no lasting damage. ^[9][5] They are a huge, temporary food source for birds, mammals, and other predators. ^[9]

Locusts, when they swarm, are agricultural disasters. ^[2] Their feeding habits involve consuming vast amounts of vegetation, leading to crop destruction across wide regions. ^[2][10] Their impact is measured in economic loss and ecological devastation of plant life, not just a noisy summer week. ^[10] If you are worried about your vegetable garden being stripped bare overnight, the concern points toward a locust swarm, not a cicada emergence. ^[2]

For someone in a region that experiences periodical cicada hatches, recognizing the timing is a practical way to confirm identity. For example, if you are in an area known for Brood X or a similar event, the timing and location almost guarantee the massive noise is from the 17-year cicadas rather than a migratory locust event. ^[5]

If you find yourself analyzing the noise, consider this practical approach: If the sound peaked, lasted for only a few weeks, and then vanished, and you saw many empty exoskeletons on the ground or tree trunks, it was almost certainly a periodical cicada brood finishing its short adult life. ^[5][9] If the sound is present every summer, perhaps changing intensity slightly year to year, but without the synchronized massive emergence, you are hearing annual cicadas or perhaps common grasshoppers/crickets. ^[2] If, however, you observe highly mobile, large bands of insects rapidly defoliating fields, you have experienced the far rarer, region-specific phenomenon of a locust swarm. ^[2][10] The seasonal rhythm of noise—loud, brief, and cyclical—is the hallmark of the cicada. ^[5]