Difference between a Locust and a Cicada

March 22, 2017 by Editorial Team

Many years ago, colonists called cicadas “locusts” based on the biblical story about the “plague of locusts.” When they found cicadas, they did not know how to classify them yet, so they used their religious background to identify them instead. This confusion is still evident these days. Although locusts and cicadas are not even remotely related, many people still interchange them. So what is the difference between a locust and a cicada? This will be discussed in this article.

Descriptions

Locust vs Cicada
A locust

Locusts are not a specific species of insect. The term “locust” actually refers to a state of grasshoppers. Those that can be considered locusts are short-horned grasshoppers that belong to the family Acrididae. They have chewing mouthparts, two pairs of wings (one narrow and the other wide), long hind legs they use for jumping, and they can grow up to 2.8 inches (7 cm). The males make a sound by vibrating their hind legs against their forewings.

Grasshoppers become “locusts” when they swarm in large numbers and feed on crops and other plants. This happens after consecutive rainy days, as these grasshoppers swarm and hunt for food. The increased movement in their hind legs activates the serotonin in their brains, a hormone that triggers them to change color to a much darker one and breed abundantly. This hormone also causes them to become sociable and nomadic when their population becomes too dense. When there is no food left, they swarm and travel together up to 100 miles to find more to eat.

Locusts are considered pests. Although they don’t bite or sting, they feed on crops and can cause much loss in agriculture. In some countries, locusts are eaten (originally as a way of controlling their population) but they have eventually become an exotic delicacy.

cicada
A cicada

On the other hand, cicadas are insects that belong to the order Hemiptera. They have stout bodies, short antennae, and large eyes. They also have long transparent wings with conspicuous veins and three pairs of legs that are all of the same lengths. Cicadas have proboscis in their mouths, a tool they use to suck plant juices for their nourishment. Both male and female cicadas have tymbals (drum-like membranes below their abdomen) but only males use them to produce sounds as loud as 120 decibels to signal mating or to keep predators away.

In general, there are two types of cicadas: annual and periodical cicadas. Annual cicadas are green and can grow up to 2 inches in length. They emerge late in the summer every year and can live up to 5 years. Periodical cicadas are dark-colored cicadas that emerge during the spring. They are the ones often mistaken for locusts because they emerge together in large numbers. They spend most of their lives underground to starve their predators, feeding on the xylem of the plants to live. They come out only after 13 years or 17 years. Millions of them become active all at the same time, which can be mistaken for a “swarm.”

Cicadas are not pests and they do not destroy plants (although sometimes they cause a small amount of damage to young trees). They are harmless to humans; they do not bite or sting. Some species, however, mistake a human for a tree, so they may poke them with their proboscis. Although they are not pests, cicadas can be annoying to people, especially when they make deafening sounds. The sounds they make can be as loud as 120 decibels which may require people to wear earplugs.

Once a cicada meets its mate, the female slits a branch where she deposits her eggs. Once the eggs hatch, the nymphs dwell underground and feed on the xylem of trees, such as oak, cypress, willow, and maple.

In some areas, cicadas are eaten and are served as a local delicacy.

Locust vs Cicada

What, then, is the difference between a locust and a cicada?

The term “locust” is actually not a specific species of insect. Locusts are just grasshoppers that are in their “swarming” phase. They are short-horned insects that belong to the family Acrididae. Cicadas, however, belong to the order Hemiptera. Locusts have chewing mouthparts, two pairs of wings, long hind legs they use for jumping, and they can grow up to 2.8 inches (7 cm). Cicadas have stout bodies, short antennae, and large eyes. They also have long transparent wings with conspicuous veins and three pairs of legs that are all of the same length. They have proboscis in their mouths, which is a tool they use to suck plant juices for their nourishment. Both male and female cicadas have tymbals. Grasshoppers become locusts when they change their color and behavior (they breed abundantly and become sociable and nomadic) due to the production of serotonin in their brains, a reaction triggered by an increased activity in their hind legs. They feed on vegetation and are nomadic. Cicadas, however, are always cicadas. They spend most of their lives underground and feed on plant sap to survive.

Also, it is important to note that cicadas do not swarm. Only locusts have this “swarming” behavior when they fly together to hunt for food. Cicadas may look like they swarm, but they actually just emerge in large groups. Additionally, locusts destroy plants but cicadas do not. Cicadas, however, slit branches to deposit their eggs. They can also be annoying especially if they make loud sounds and if they mistakenly poke humans with their proboscis.

Both insects can produce sounds. Male locusts make a sound by vibrating their hind legs against their forewings, whereas male cicadas make a sound by using the drum-like membranes below their abdomen (called tymbals).

Comparison Chart

LocustCicada
Does not refer to a specific species of insect but a state of grasshoppers that belong to the family AcrididaeAn insect that belongs to the order Hemiptera
Has chewing mouthparts, two pairs of wings (one narrow and the other wide), long hind legs for jumping, and short horns; can grow up to 2.8 inchesHas a stout body, short antennae, large eyes, long transparent wings with conspicuous veins, three pairs of legs of the same length, proboscis in its mouth, and tymbals below its abdomen; can be green or black
Male locusts make a sound by vibrating their hind legs against their forewingsMale cicadas make a sound by using the drum-like membranes below their abdomen (called tymbals)
Feed on cropsFeed on the xylem of plants
Breeds abundantly, is gregarious, and becomes nomadic when the population becomes too dense; swarms and travels with each other up to 100 miles to find foodDwells underground; in order to starve its predators, it emerges together with the others after a number of years
Does not bite or sting; eats crops and destroys plants; considered a pestDoes not destroy plants; does not bite or sting although it may mistakenly poke a human with its proboscis; makes loud sounds (up to 120 decibels) which can be annoying
Locusts swarm to find food and move to different placesCicadas do not swarm; they emerge in large numbers