Review author: “ZooVita”
Locusts are beneficial in countries where they are eaten. Dry crushed locusts are added to the diet of farm animals as protein food; the larvae and dead insects fertilize the fields. But the harm from the actions of an insect is not comparable to these positive aspects.
Characteristics of locusts
The insects belong to the order Orthoptera, from the family of true locusts. The body is in the shape of an elongated oval, at one end of which is the head, at the other - the ovipositor. The length can be 8 cm. The head tapers towards the oral apparatus.
In the photo of the locust you can see simple and compound eyes, with antennae extending upward from them. Two of the six legs are directed forward in the direction of movement, two pairs support the body from contact with the ground. The last two pairs are curved with joints in the opposite direction, extending above the surface of the body.
The folded wings lie along the body. They are capable of transporting insects over a distance of over 100 km per day. The respiratory organs are located along the chest and abdomen. The hearing organs are located between the chest and abdomen.
Insects make characteristic sounds when the barbs from the thighs of the hind legs rub against the elytra. The coloring performs protective functions and depends on the habitat. The transition from one phase to another changes color.
Morphology
Adult insect
The body is rusty brown or light brown in color with dark or light yellow spots. The antennae are reddish, longer than the head and chest combined. On the chest there are two clearly visible white or pale yellow stripes in the shape of the letter "X". The elytra are longer than the abdomen, extend far beyond the tibia of the hind legs, almost transparent, with dark brown to black spots and veins. The length of males is 20–28 mm, females - 28–30 mm. The eyes are relatively small. The femurs of the front legs are thickened and fawn; the thighs of the hind legs are fawn, with three clearly distinguishable black spots on top. The tibiae of the hind legs are red, gray at the base with a yellow ring.
Male, Kazakhstan
The body of the gregarious form is yellowish, the hind thighs have faintly visible dark spots and stripes, often without them at all. The wings are longer. Individuals of the solitary phase are grayish-brown, the hind femurs have bright dark spots, and the wings are shorter.
Female, La Palma (Canary Islands)
Egg
It looks like rye grain, pale yellow in color. The eggs are located in a cylindrical ootheca with a flat lid, 20–30 mm long. Each contains 14–40 eggs, arranged in 4 rows.
Larva
Outwardly it resembles an adult insect. Initially white and wingless, gradually becoming gray or brownish-black. Starting from the second instar, characteristic stripes in the form of the letter “X” appear. At the third instar, the rudiments of wings appear, at the fourth instar the nymph becomes olive-red, and at the fifth instar it acquires the color characteristic of an adult insect.
Fourth instar larva, near Birlik, South Kazakhstan region
Types of locusts
Depending on the habitat, morphological differences in locusts have formed. The environment has influenced the color, size and behavior of insects, and species diversity is enormous.
Asian locust
It has almost transparent wings, cloudy, indistinct color, with thin veins. There are green specimens, brown and gray in color. The color on the thighs and legs is of a darker shade. Females reach 6 cm, males are smaller. They have taken root in Asia, Europe, and southern Russia.
Moroccan locust
It is colored in shades of brown. Covered with small specks. There are patterns on the back. It prefers the hot and dry climate of Africa. It reaches 2 cm in length.
Italian locust
Mostly dark shades of brown, varying on different parts of the body, with black splashes. Females grow to 4 cm. Males are smaller. Flocks are common in countries near the Mediterranean Sea, Europe and Siberia.
Desert Locust
Gray-yellow in color with brown wings, the insect hides in nature with an abundance of sand. It has taken root near the desert in northern Africa. Large specimens can reach a length of 8 cm.
Siberian filly
Nondescript colors of green and brown shades predominate. Reaches a length of 3 cm. Selects mountainous surfaces of the Caucasus, Mongolia, and Siberia for living.
Rainbow Locust
Like the entire population of Madagascar, she is unusual and extraordinary. In order not to attract attention, it has a bright color, a combination of blue, red, yellow colors. Poisonous. Can grow up to 7 cm.
Blue-winged filly
Small specimens up to 2.5 cm, with a brown body and blue wings. For living it chooses steppe and forest-steppe lands.
Egyptian filly
The color is light shades of gray and green. Habitat: North Africa and European countries. Grows up to 7 cm.
Meaning for humans
A polyphagous pest that damages the leaves of many crops, in particular cereals (wheat, corn, barley, millet), legumes (alfalfa, clover), tobacco, sugar beets, various vegetables and melons. Young plants are completely eaten. On ripening plants (cereals, cotton), the stems are often chewed, as a result of which damaged crops take on the appearance of being mown down or damaged by hail.
Until the second half of the 20th century, it posed a serious threat to agriculture in Mediterranean countries, Central Asia and even Central Europe. Regular outbreaks of the herd form led to the destruction of cultural plantings. As of the 1990s, the situation has changed. Thus, in France, the range of the insect has narrowed significantly to a small steppe zone in the south; the appearance of a gregarious form is unlikely. In Hungary, the last outbreak was recorded in 1948-1949, the number of the species is low. But in southern Spain, natural reservoirs of the Moroccan locust are still large, which led to outbreaks in 1983 and 1992. In Crimea, a number of outbreaks were recorded in the 1920s, after which, under anthropogenic pressure, the number of the species became so low that it was even proposed to include the species in the Red Book. However, the number in Central Asia and North Africa remains high. In 2016-2018, outbreaks of the gregarious form were observed in the North Caucasus, from where the locusts spread to the Krasnodar Territory and even to the Crimea.
Migration of larvae, Dagestan
Life cycle of locusts
There are 2 phases that affect lifestyle, significantly different from each other. The way to distinguish locusts in phases is to distinguish the morphological characteristics of the insects.
In the single phase it takes on a protective color, mainly shades of green. The insect lives on green plants, feeding on leaves. Locusts are divided into females and males. Insects spend their time inactive; all life stages pass alone.
This stage signifies the comfortable existence of the locust. There is enough food.
Insects of the gregarious phase exist together. Each individual has a bright color. Adults fly. They behave actively, there are no anatomical differences based on gender. Unfavorable conditions have arisen in the existence of insects, individuals are mobilized to search for food. Insects lay offspring.
Locust lifestyle
The new generation stays in a pack and has new external characteristics. A large locust appears, its wings capable of moving it a considerable distance. Fillies turn into locusts under the influence of factors: the need for protection from predatory relatives and lack of protein food.
The insect is diurnal. The diet includes only plant foods. Cannibalism occurs when there is an existential threat.
Locusts adapt to life in any conditions except harsh cold climates. The presence of bodies of water is not a prerequisite.
Locust breeding
The insect is oviparous, buries its offspring in leaves on the surface of the ground or in the soil. Requires warmth for development. The eggs are protected by a thick coating. After laying eggs, the individuals die.
At positive air temperatures, larvae are released from the eggs. After several molts, the individuals are fully formed. Larvae that appear in large clusters will not disperse throughout the area. The incentive to join a flock will be stressful situations and the presence of other relatives nearby.
Locusts bury clutches while searching for food. Eggs that find themselves far from the habitat of their parents, in small quantities, will spread throughout the territory, developing in a solitary phase.
Predators
The species' numerous predators include blister beetle larvae Zonabris variabilis and Epicauta rufidorsum, as well as several species of buzz flies.
Variable blister (Mylabris variabilis)
Epicauta rufidorsum
What is included in the locust diet
Insects move long distances in search of food. A single individual requires a small amount of plant food to maintain life. Insects gnaw leaves and grass.
Swarms include in their diet everything that locusts eat. Cereals, grass, leaves, bushes, reeds encountered along the way. Dry and old plants will be used for food.
Nutrition
Locusts feed on many types of plants, and unfortunately for people, they also feed on agricultural crops. This insect has an excellent appetite and the locust can force people whose crops have come under its terror to suffer from hunger.
She eats a large amount of food per day, approximately equal to her own weight. And the offspring of one individual is enough to eat enough grass in a season to feed two sheep. Fields, vegetable gardens, forests, meadows - all this can be eaten by a swarm of locusts.
The photo shows a swarm of locusts
Sometimes locusts also attack orchards - for example, they will eat grapes, starting with the leaves and ending with the bark and berries. The vegetation of reeds, reeds, hemp, flax, buckwheat, cereals - all this is used as food for the locusts. In addition, if there is a lack of food, it can attack the thatched roofs of houses, and on a long journey without food, it can eat its weaker brothers.
Why are locusts dangerous to humans?
Insects gather in flocks of several thousand individuals. When burying clutches of eggs, individuals are particularly voracious. Lack of food leads to a decline in populations. Sudden changes in air temperature negatively affect their life.
Ways to deal with locusts include destroying clutches and using chemical insecticides that repel and poison insects.
Lifestyle and habitat
A distinctive feature of the locust is its ability to both live alone and gather in giant communities. If an individual is solitary, it behaves quite calmly, is sedentary and not voracious. Destructive consequences from its presence are usually not observed.
When food disappears, insects try to lay as many eggs as possible, from which gregarious individuals hatch, ready to move across vast spaces. These offspring are larger, and their wings are better adapted for long flights. Giant swarms of locusts sometimes contain up to half a billion individuals. Such flocks have amazing mobility and interact as a single organism.
It is believed that the signal for mass laying of eggs may be a lack of organic substances and amino acids in the body of individuals due to insufficient food in dry years.
