What are the appearance characteristics of locusts?

Locusts are also called grasshoppers, grasshoppers, grasshoppers and grasshoppers.

Features: usually green, brown or black, with large head and short tentacles; The front chest backboard is hard, extending to the left and right like a saddle, and the middle chest and the back chest can't move when they heal. Foot extension, especially the muscles of hind legs, is thick, short and powerful, and the exoskeleton is hard, so it is an expert in jumping. The tibia has a sharp saw and is an effective defensive weapon. The ovipositor is not obvious, which is the biggest difference from the owl. Feeding habits: like to eat thick leaves, such as sweet potatoes and water spinach, abnormal: not completely abnormal.

locust

Observation on the shape of locusts

The female is big (40-50mm) and the male is small (30-40mm). The body is divided into three parts: head, chest and abdomen.

(1) header

Oval, exoskeleton becomes a skull, with a blunt head above the skull, a slightly square forehead in front, a horizontal rectangular lip base below the forehead, and cheeks on both sides of the forehead.

Compound eye 1 pair, oval, brown, located on both sides of the head. Observing the surface of compound eye with a magnifying glass, we can see that many small hexagonal eyes are embedded in a honeycomb structure.

There are 3 monocular eyes, light yellow, one in the middle of the forehead, and the other two above the inner sides of the two compound eyes.

The antenna 1 pair evolved from the second appendage (1 and the third appendage degenerated). Located in front of the inside of the compound eye; Slender and filiform, it is composed of stalk nodes, stem nodes and whip nodes, and is divided into many sections.

The chewing type consists of three pairs of appendages: head, upper lip and tongue (page 269 of General Zoology).

① Upper lip: one piece connected below the base of the lip and covering the front of the mouthparts;

② Maxillary: (maxilla) 1 pair. The fourth pair of appendages evolved to lie under the cheek. Inserting a dissecting needle along the subgingival suture, and separating the suture connection, the maxilla can be taken out. The upper jaw has incisors and molars, which are hard, brown and asymmetrical.

(3) Mandibular: (mandible) 1 right, the fifth pair of appendages evolved, located behind the maxilla, and the base was pulled off with tweezers, showing that there were joints at the base, a stem joint in the middle, a petal-shaped outer jaw leaf on the outside, an inner jaw leaf with sharp teeth on the inside, and five lower (small) jaw whiskers on the tiny negative jaw whiskers;

④ Lower lip: 65,438+0 pairs. The sixth pair of appendages evolved, and the left and right sides healed into a whole. It was located behind the chin, with a crescent-shaped posterior chin at the base, a flaky anterior chin in front, a pair of three lower lip whiskers on both sides, and 65,438+0 pairs in front of the anterior chin.

⑤ Tongue: 1, oval, with petiole at the base; There are several chitin dentate processes on the surface of the tongue.

(2) Chest

It is connected to the head by a slightly contracted membranous neck, which consists of three parts: the front chest, the middle chest and the back chest.

Each thoracic segment of the exoskeleton consists of four bone plates, namely, the back plate, the side plates on both sides and the web plate on the ventral surface.

① The backboard develops into a chest saddle shape, extending to both sides and the rear; The middle and rear thoracic backboards are often covered by the rear edge of the anterior thoracic backboard, which is square and divided into several small bone pieces;

(2) The anterior chest lateral plate is located at the front end below the back plate and degenerates into a small triangular bone block; The medial and posterior thoracic lateral plates are developed and divided into anterior and posterior plates by lateral sulcus.

(3) The webbed is rectangular in the chest, horizontally curved in the center, with hooked webbed processes; The middle and rear thoracoabdominal plates are integrated into a whole and divided into several bone pieces.

Feet: A pair of segmented feet are attached to each thoracic segment, which consists of basal segment, trochanter segment, thigh segment, tibia and fibula segment, tarsal segment and tarsal anterior segment. The tarsal joint is divided into three segments, of which the first segment is longer, forming three false segments; The anterior tarsal joint includes 1 claw and the intermediate pad between claws. The hind legs are thick and suitable for jumping, which is called jumping foot; Both forefoot and midfoot are walking feet.

There are 1 leathery long and narrow compound wings (front wings) in the middle of wings and chest and back; There are 1 pair of fan-shaped membrane wings (posterior wings) on the posterior chest, and the wing veins are obvious, which are folded under the compound wings at rest. There are 1 pairs of valves at the anterior edge of the middle and posterior thoracic lateral plates.

(3) Abdomen

It consists of 1 1 nodes.

Each abdominal segment of the exoskeleton has only a back plate and a web plate, and the lateral plate degenerates into a lateral membrane connecting the back plate and the web plate. The first abdominal segment is closely connected with the back chest and cannot move; The spine of the ninth and tenth abdominal segments is shortened and healed, and there is a shallow groove between them; The back plate of the eleventh section is triangular and covers the anus, which is called the anal upper plate, and there are anal side plates on both sides, which are the webbed of the eleventh section; There is a tail beard on each side of the tenth trailing edge, which is an appendage of the eleventh section. The net number of cotton locust is different from that of male locust. There is no net in the ninth and tenth sections of the female locust, and a pointed ovipositor extends into the back end of the eighth section. The ninth and tenth webbed of the male worm healed, and the tip of the male worm pointed into the lower reproductive plate.

The female of the external genitalia is the ovipositor, while the male is the copulatory organ.

① The ovipositor consists of a pair of back flaps and a pair of abdominal flaps, which are located at the end of abdomen;

② The mating apparatus is a pair of hooked penises. You can see it by pressing the reproductive plate.

The auditory organ is 1 pair of oval eardrums, which are located on both sides of the first abdominal segment.

Valve *** 10 pairs, chest 2 pairs, located in the front edge of the middle and rear chest lateral plates; There are 8 pairs of abdomen, which are located in front of the lower edge of 1-8 abdominal dorsal plate. You can use a magnifying glass to observe the opening and closing of the valve when cotton locust breathes.

Reproductive and developmental processes of grasshoppers

Its adults have a pair of developed jaws, mainly eating grass, especially like to eat gramineous plants, such as rice, wheat, sorghum, corn and bamboo leaves. Gramineous weeds are dense here, which is a vast wasteland and an ideal habitat for locusts. Where locusts swept, Gramineae plants were eaten up, and almost everything it could bite was spared. Swarms of locusts can turn green land into wasteland. Locusts are good at flying and jumping, and a pair of tentacles in the head are organs that combine smell and touch. Its chewing mouthparts have a pair of developed jaws with teeth, which can bite off the stems and leaves of plants. Its hind foot is very strong, and it mainly depends on it when jumping. When locusts fly, their hind wings play a major role, and when they rest, their front wings cover their rear wings for protection. The female insect has a strong "ovipositor" at the end of her abdomen, which can be inserted into the soil to lay eggs. Locust spawning sites are mostly wet river banks, lakes, foothills and ridges. Every 30 to 60 eggs are grouped together. Immature locusts hatched from eggs are called "locusts" and need to molt five times to develop into adults. A large number of eggs can be hatched after the rain clears. Locusts also have amazing flying ability, which can fly continuously 1 ~ 3 days. When locusts fly by, the sound of swarms of locusts flapping their wings is amazing, just like the roar of a storm in the ocean.

The life of locusts begins with fertilized eggs. The larvae just hatched from eggs have no wings and can jump, which is called jumping insects. The flea is similar in shape and living habits to adults, but smaller in size and immature in reproductive organs, so it is also called nymph. If an insect grows up gradually, it will shed its original exoskeleton when it is restricted by the exoskeleton and can no longer grow up. This is called molting. Nymphs molt five times in their lives. From hatching to molting for the first time, the age is 1, and every molting thereafter, the age increases 1. After the 3rd instar, the wing buds are remarkable. Become a flying adult after 5 years old. It can be seen that the individual development process of locusts goes through three stages: egg, nymph and adult. A developmental process like this is called incomplete metamorphosis. When an insect develops from a fertilized egg to an adult, it can produce the whole individual development history of its offspring, which is called the first generation. Locusts can produce two generations of summer locusts and autumn locusts a year in some parts of China, so there are two generations.

People have long noticed that serious locust plagues are often accompanied by serious droughts. There is a record of "drought locust" in ancient books in China. In recent years, several major locust plagues in Africa are also related to the severe drought in the region. The main reason for this phenomenon is that locusts are warm and dry insects, and the arid environment has many benefits for their reproduction, growth and survival. Because locusts lay eggs in the soil, the soil is relatively solid, and the water content is 10% ~ 20%, which is most suitable for them to lay eggs.

Drought makes locusts multiply and grow rapidly, and there are two reasons for the disaster. On the one hand, in dry years, due to the drop of water level, the soil becomes more solid, the water content decreases, the ground vegetation is sparse, and the number of eggs laid by locusts increases greatly, reaching 4000-5000 eggs per square meter of soil in many cases, with 500-80 eggs in each egg block, that is, 200,000-400,000 eggs per square meter. At the same time, in dry years, the water surface of rivers and lakes shrinks and the low-lying land is exposed, which also provides more suitable places for locusts to lay eggs. On the other hand, plants that grow in arid environment have low water content, and locusts feed on it, which makes them grow faster and have higher fertility.

On the contrary, the rainy and humid environment has many adverse effects on the reproduction of locusts. The plants eaten by locusts have high water content, which will delay the growth of locusts and reduce their fertility. Rainy and humid environment will also make locusts epidemic diseases, and rain and snow can directly kill locust eggs. In addition, the increase of natural enemies such as frogs will also increase the mortality rate of locusts.

After mating, the female locust inserts the oviposition tube into the soil with a depth of 10cm, and lays about 50 eggs.

When laying eggs, the female will secrete white material to form a cylindrical plug, and then lay eggs.

This is an egg that has been developed for 19 days; At about 24℃, locust eggs can hatch in about 2 1 day. The hatched nymph crawls out of the soil. At this time, its appearance is very similar to that of adults, except that it has no wings and its body color is lighter. Larvae looks more like adults in the first year or two, but the head is out of proportion to the body. Winged buds grow at the third age, which is obvious at the fourth age. When the nymph is five years old, it will climb to the plant and hang for a while, and then the adult will come out. (Morphology and living habits): Both adults and larvae of grasshoppers can chew the stems and leaves of plants with developed chewing mouthparts.

Adult hind limbs and legs have a series of mastoid processes equivalent to elastic devices, and the base of radial veins of anterior wings has thick veins equivalent to chordal devices. When they rub, the vibrating area of the vibrating wings can make sound, which is their sounder. The auditory organs of locusts are also very special, located on the side of the first abdominal segment.

Prevention and cure method

1. Agricultural control

(1) Build water conservancy projects to ensure that there is no disaster in droughts and floods.

(2) Reclaim wasteland in a large area, change locust habitat and reduce the area of occurrence base.

(3) Planting trees to change the microclimate in locust areas and reduce the suitable places for locust spawning and reproduction.

(4) Improve cultivation techniques to control locust eggs, adjust measures to local conditions, change crop layout and reduce locust harm.

biotic-control

(1) In locust-infested areas, agricultural and biological pesticides with high efficiency and low toxicity are used to protect predatory natural enemies in locust-infested areas.

⑵ Microsporidia was applied in a large area.

Matters needing attention in raising locusts

I. Selection and identification of breeding locust provenance

The methods to determine the species of locusts are: (1) consulting locust classification experts. (2) refer to the locust key table or atlas. ⑶ Consult an experienced locust farmer. (4) Send the locust species to customers for identification and review.

Common species of cultivated locusts are: oriental migratory locust, cotton locust, Chinese rice locust, Chinese grasshopper and so on. These varieties have their own advantages and disadvantages, so it is necessary to comprehensively consider their growth cycle, algebra, taste, food, size, varieties needed by customers and other factors, and select breeding varieties in combination with local climate and food sources.

Second, the construction of locust breeding shed

The area of the shed depends on the number of locusts. Generally, about 300 adults can be raised per square meter. In order to breed migratory locusts in natural conditions, the shed construction must be completed before the end of April, because the eggs of northern locusts can usually hatch in May.

Third, nymph management.

(1) Grasshoppers eat very little and like to eat fresh and tender plants. During this period, grasshoppers are very delicate, so we should pay attention to rain protection and prevent drowning. ⑵ The temperature is controlled at 25-30℃, the illumination is above 12 hours, and the humidity is kept at about 15%. Under this condition, locusts are the most active and like to eat, which is conducive to growth. (3) The food intake of locusts over three years old is gradually increasing. At this time, it is necessary to ensure that there is enough food in the shed, otherwise it will affect its normal growth and lead to cannibalism. (4) Keep the shed clean and clean it every 1-2 days to prevent diseases.