Locust vs. Cicada: What Is the Difference?
Locusts and cicadas are completely different insects. A locust is a short-horned grasshopper that may form swarms, while a cicada is a sap-feeding true bug known for its loud male song and, in some species, long underground juvenile life. The old nickname “17-year locust” for a periodical cicada is a misnomer.
What Kind of Insect Is a Locust?
A locust is a grasshopper in the order Orthoptera and family Acrididae. It has large hind legs built for jumping, short antennae compared with crickets and katydids, and chewing mouthparts. Only some grasshopper species are locusts in the strict sense, meaning they can change from a solitary form to a gregarious, swarm-forming form.
Locusts feed on plant tissue. In a dense band or swarm, they can chew through grasses, leaves, shoots, flowers, seeds, fruit, and crops. The scale of many insects feeding at once is what makes an outbreak damaging.
What Kind of Insect Is a Cicada?
A cicada belongs to the order Hemiptera, the true bugs. It has large compound eyes, clear veined wings, and a beak-like mouthpart used to take fluids from plants. It does not have the enlarged jumping legs or chewing mouthparts of a grasshopper.
Adult male cicadas make their familiar sound with structures called tymbals. The chorus is about attracting mates, not a locust swarm. University of Illinois Extension notes that cicadas are often mistaken for locusts, especially when many periodical cicadas emerge at once.
Why Are Cicadas Called Locusts?
The nickname has been used for generations because periodical cicadas can appear in huge numbers and their song is memorable. Their mass emergence may have reminded early observers of accounts of locust swarms. Similar abundance, however, does not make them close relatives.
University of Maryland Extension is direct on this point: 13-year and 17-year cicadas are not true locusts. Cicadas and locusts have different body plans, diets, life cycles, and insect orders. Calling a cicada a locust is common, but it is not scientifically accurate.
How Do Their Life Cycles Differ?
Locust eggs are laid in soil. Wingless young, called hoppers, hatch, molt several times, and become adults within a season or on a schedule shaped by their species and weather. Some species can build density quickly after good breeding conditions and then form bands or swarms.
Cicada young, called nymphs, hatch from eggs laid in twigs and then drop or move into the soil. They feed on fluids from tree roots for years. Periodical cicadas spend 13 or 17 years underground before a synchronized adult emergence; annual cicadas have overlapping generations and appear every summer.
How Do Their Diets Differ?
Locusts chew solid plant parts. Their eating can leave missing leaf tissue, clipped shoots, and stripped crops. Their broad diet and group feeding are central to their status as agricultural pests in outbreak regions.
Cicadas use a piercing-sucking mouthpart to take xylem fluid from woody plants. They are not leaf-chewing insects, and they do not form migratory plant-eating swarms. Adult cicadas may be a nuisance because of noise or because many emerge together, but their feeding pattern is not a locust’s feeding pattern.
How Do They Look Different?
Look at the legs and wings. A locust has conspicuously enlarged hind femurs for jumping and a grasshopper-shaped body. A cicada has a broad head, large eyes, clear roof-like wings, and legs made for clinging to bark rather than launching a long jump.
Color is less dependable. Locusts and cicadas can both be brown, green, or patterned. A periodical cicada often has a dark body, red eyes, and orange wing veins, but the most dependable clue is the combination of body shape, mouthparts, and behavior.
Do Cicadas Damage Crops Like Locusts?
No. Large cicada emergences can injure small trees when females cut slits in twigs to lay eggs, and young nursery plants may need protection. Established trees generally tolerate the damage better. Cicadas do not strip field crops and pasture in the way a locust band or swarm can.
True locust outbreaks matter because the insects move through vegetation as large populations of plant chewers. FAO identifies the Desert Locust as a major threat to crops and forage in affected regions. The ecological and agricultural questions are therefore quite different.
What Is the Simple Answer?
A locust is a grasshopper relative that chews plants and may swarm. A cicada is a sap-feeding true bug that sings, develops underground, and is sometimes given the inaccurate nickname locust.
For a closer look at the locust side of the comparison, see locust size, color, and behavior. The shared word in old folklore does not mean these insects share the same biology.
