Are dragonflies, crickets, longicorn beetles and seven-star lady beetles beneficial insects or pests common in rural areas?

Dragonflies, crickets, longicorn beetles and ladybugs are often seen in rural areas, but few people have really thought about whether they are beneficial insects or pests to humans. In the insect ecosystem, there is no distinction between beneficial insects and pests. These two words are purely human definitions. Generally speaking, what is beneficial to humans is beneficial insects, and vice versa is pests.

1. Dragonfly

Dragonfly is a typical incomplete metamorphosis insect, divided into two families, the family Sphinidae and the family Pieridae. It does not need to go through the process of pupation from the stage of larva to adult. It only goes through three stages in its life: egg, larva and adult. The larva is aquatic, while the adult is a terrestrial insect with flight ability.

Are dragonflies beneficial or harmful?

Dragonflies are beneficial or harmful to see in stages, larvae of dragonflies, that is, water fish, is to live on small fish, tadpoles, very fierce, is a pest of cultured fish, especially fry cultivation and tropical fish breeding, must be cleaned up.

After mature emergence, beautiful dragonflies are big beneficial insects. They feed on flies, mosquitoes, moths and other pests. They are almost born to catch pests. They are of great help to human life. They are not only good for human health, but also play a great role in the high yield of farmland crops.

Dragonflies also have an amazing appetite. It is a carnivorous insect that specializes in mosquitoes, flies and other small insects as food. A commonly known as "green head Leng" green dragonfly, a day can not care about eating about 2000 aphids and other small insects. It eats mosquitoes, flies and the like, of course, in addition, any small moths and insects that can fly and crawl, it welcomes. In this way, a large number of pests are eliminated for mankind, and it is well deserved to call them "beneficial insects".

How long can dragonflies live?

Dragonfly larvae spend at least one year in the water, and the time required for the whole larval stage varies according to different species and seasons, ranging from one month to three or four years. Longer ones take seven or eight years to emerge as adults. Adult dragonflies live only one-tenth as long as larvae, only one to eight months, but dragonflies are still considered long-lived insects.

2. cricket

Crickets scientific name is cricket, for insects Orthoptera crickets invertebrate, do not cry, but the male can make a sound through wing friction, distributed widely, almost all over the country. Male crickets are aggressive, so people like to keep them for watching and fighting crickets.

Are crickets beneficial or harmful?

Crickets are pests. Crickets are important agricultural pests in Northeast China, North China, the lower reaches of Yangtze River and South China. They destroy roots, stems, leaves, fruits and seeds of various crops, especially seedlings. In the south, crickets destroy 11 - 30 per cent of peanut seedlings. They also harm corn, jute, tobacco, cotton, soybeans and cassava, often resulting in seedling shortages and affecting harvests.

What do crickets eat?

Crickets living in the wild generally feed on buds, tender leaves and roots, while crickets raised by humans will choose some foods in addition to various fresh vegetables and fruits, and make them into rich nutritious meals according to proportions. Regular, quantitative feeding every day, to promote cricket can grow healthier, more aggressive.

3. Longicorn

Longicorn is a general term of Coleoptera Polyphagous longicorn insects. It has chewing mouthparts and long antennae, often exceeding the length of the body. There are more than 20000 species in the world. Larvae and adults prefer to move on trees, such as mulberry, willow, poplar, citrus, pine, etc. There are many species of longicorn breeding in it.

Is longicorn beetle a beneficial insect or a pest?

Longicorn beetles are the main pests in forestry production, crop cultivation and construction timber. Longicorn beetles are mainly woody plant pests, in the larval stage of moth damage trunk, branches and roots. Some harm herbaceous plants, larvae live in stems or roots, such as chrysanthemum longicorn, melon vine longicorn, etc. Individual species such as cotton capsule longicorn, then damage cotton capsule. There are a few species, larvae do not live in plant tissue, but in the soil feeding roots, such as large teeth and curved teeth saw longicorn, grass longicorn and so on.

What does the longicorn eat?

Longicorn is a herbivorous insect, known to feed on pollen, tender bark, twigs, leaves, roots, tree sap, fruits, fungi and other different habits, flower longicorn often feed on pollen, groove longicorn often eat tender bark, twigs and leaves. Longicorn beetle is the main pest in forestry production, crop cultivation and building wood, which will harm most pine, cypress, willow, elm, walnut, citrus, apple, peach and tea, some cotton, wheat, corn, sorghum, sugar cane and hemp, and a few wood, buildings and furniture.

4. ladybug

ladybug is a general term for the round protruding beetle of Coleoptera ladybug family. Its body color is bright, often with red, black or yellow spots. It is also called fat small, red lady, flower elder sister, beetle, etc., even because some species have smelly secretions, it is commonly known as smelly turtle seed. It will experience four stages of complete growth in its life: egg, larva, pupa and adult.

Is ladybug a good bug or a pest?

Ladybugs have both pests and good ones. ladybug species are very diverse, from the feeding habits can be divided into carnivorous ladybug and herbivorous ladybug, adult carnivorous ladybug will prey on any tender soft insects, the most favorite is aphid, such as seven ladybug. Most species feed on Solanaceae, Cucurbitaceae and Compositae, such as potato ladybug and nightbug, which collectively eat eggplant and potato leaves and are considered pests.

Which ladybugs are pests?

1. Ladybug: The parasitic plants of Ladybug are potato, eggplant, tomato, green pepper and other Solanaceae vegetables and cucumber, wax gourd, loofah and other cucurbitaceae vegetables. In addition, it also harms beans, solanum nigrum, sour juice, datura, tobacco, etc. Adults and larvae eat mesophyll, and the upper epidermis remains are reticulated. In serious cases, the whole leaves are eaten up. In addition, the surface of sweet fruits and melons becomes hard and bitter, affecting the yield and quality.

2. Coccinella decimpunctata: Both adults and larvae of Coccinella decimpunctata feed on leaves, which are holed or notched, or eat up leaves and leave only veins. After mature larvae drill into the soil to build pupae, adults move to host damage after emergence, mainly feeding on grapes, wild grapes and five convergence berries.

3. Potato ladybug: potato ladybug adults and larvae peel mesophyll on the back of leaves, leaving only epidermis, forming many irregular translucent fine concave lines, such as basket bottom, and can also eat leaves into holes, even leaving only veins. In severe cases, the affected leaves dry and brown, the whole plant dies, the fruit is often broken, the tissue becomes stiff, rough, bitter and inedible.

Which ladybugs are beneficial?

1. Coccinella septempunctata: Coccinella septempunctata is a beneficial insect. Adults can prey on wheat aphids, cotton aphids, locust aphids, peach aphids, scale insects, ticks and other pests, which can greatly reduce the damage caused by pests to trees, fruits and various crops. It is called "live pesticide" and is widely distributed throughout China.

2. Coccinella axyridis: In addition to preying on cotton aphids, adults and larvae of Coccinella axyridis can also prey on eggs and young larvae of cotton bollworm. The maximum number of eggs eaten by adults per day is about 70, and the larvae do not prey on eggs of cotton bollworm. For young larvae of cotton bollworm, there are 70 adults and 69 fourth-instar larvae.

3. Six ladybugs: Six ladybugs are also called six spotted ladybugs. The larvae are black in color and have white longitudinal spots in the center of the back. They feed on a variety of aphids. The adult patterns vary by more than 20 species, but the patterns on the prothorax are relatively stable. They are widely distributed in flat to low-altitude mountainous areas. They are common on plants with aphids and can be seen all year round.

4. Ladybug: Ladybug is a beneficial insect, which will prey on aphids, leafhoppers, planthoppers, etc. In July and August of cotton field, it preys on eggs and young larvae of aphids, cotton bollworms and other pests. At the same time, July to September is also an important natural enemy in the orchard, feeding aphids, leafhoppers, planthoppers and other pests in the apple orchard.

5. Ladybug: ladybug adult body length 0.8~17 mm, oval or long oval, hemispherical on the back, flat on the ventral surface, rare in quantity, preying on scale insects, and adults and larvae preying on sugarcane cotton aphid, distributed in Guangxi, Fujian, Taiwan, Guangdong, Guizhou, Yunnan and other places.

6. Australian ladybug: Australian ladybug is an agricultural beneficial insect, native to Australia, likes shade environment, has pseudo-death habit, often concentrates on feeding female adults of blowing scale at the beginning of hatching, and gradually disperses later. At present, more than 50 countries have introduced Australian ladybug to control blowing scale. China has introduced it since 1955 to carry out research and utilization, effectively controlling the occurrence of blowing scale, which is known to be distributed in various citrus producing areas in the south.

What do seven-star ladybugs eat?

Coccinella septempunctata is a kind of beneficial insect. Its adults can prey on wheat aphid, cotton aphid, locust aphid, peach aphid, scale insect, tick and other pests. It can greatly reduce the damage of trees, fruits and various crops by pests. It is called "live pesticide". It is nontoxic and harmless to humans, livestock and natural enemies. It has no residue and does not pollute the environment.