Do you know when insects first appeared on Earth?

Insects began to appear in the Devonian period of the Paleozoic Era (the existence of the earth is divided into 6 generations of the Azoic, Prothozoic, Protzoic, Paleozoic, Mesozoic and Cenozoic), which has been 100 million years ago, and appeared on the earth nearly 200 million years earlier than birds, so insects can be called the old inhabitants of the earth.

Although the body of insects is so small, and the evidence that they appeared so early on the earth, and the fossils left behind are so small, scientists have relied on their extremely rich imagination and the fossils preserved in the earth's crust to compare them with similar living organisms (living fossils) existing in nature, providing people with clues to the origin of insects. The history of the development of insects on the earth is uncovered with the change of all things, the continuation of time and the continuous evolution and development.

The earliest ancestors of insects lived in water, it looks like a worm, also like an earthworm, the body is divided into many movable links, the front link has bristles, when moving constantly to the surrounding touch, playing a sensory role. Underneath the head and the first link, there is a small hole that looks like a food harvest. This simple worm-shaped animal is considered to be the common ancestor of rings, hookopods and arthropods, and is also the ancestor of insects.

With the extension of time, the limb function of insects has evolved and gradually appeared on the land stage. In order to adapt to life on land, their body structure has undergone great changes, from the original more annular body segments and appendages to the three major body segments of the head, thorax and abdomen. This evolutionary process has taken about 200 million to 300 million years, and it continues to evolve at a slow pace.

The survival and development of insects on the earth has not been smooth sailing, and there have been several major ups and downs. One of the more prominent major devastating disasters occurred in the Mesozoic Era, between 100 million and 100 million years ago. At that time, the climate of the earth changed abruptly, the vibrant land was barren due to drought, and the forest oases were confined to small areas along the shores of lakes and coastal areas, which deprived herbivorous insects of their food sources.

In this stage of mutation, some reptiles that originally lived in the water area changed their living habits and body structure in the water due to the shrinking of the water, and evolved into a flying and herbivorous Archaeopteryx that mainly predated insects, which made some winged insects flying between forests and green spaces lose their airspace for survival. However, there are also highly adaptable insect species that still use their own strengths to tenaciously continue their populations. <>

Insects are of great variety and morphology, belonging to the arthropods of invertebrates, and are the most abundant animal group on the planet, accounting for more than 50% of all biological species (including bacteria, fungi, and viruses), and their traces are found in almost every corner of the world.

Until the beginning of the 21st century, there were more than 1 million species of insects known to humans, but there are still many species yet to be discovered. Insects are the most diverse and abundant in the animal kingdom and have a significant impact on agricultural production and human health [1]. The most common are locusts, butterflies, bees, dragonflies, flies, grasshoppers, cockroaches, etc.

Not only are there many species of insects, but the number of individuals of the same species is also staggering. The distribution of insects is so wide that no other class of animals can compare with it, and it is almost all over the earth. There are different types.

Most insects can be used as specimens, and they are a good biological resource that humans can use. <>

Evolved from single-celled organisms.

Recent studies suggest that there may be 10 million species of insects worldwide, accounting for about half of all living species on Earth. However, there are only 1 million species of insects with names and surnames, accounting for 2 3-3 4It can be seen that there are still 90% of the species of insects in the world that we do not know; According to the most conservative estimates, there are at least 3 million species of insects in the world, and there are still 2 million species to be discovered, described and named.

Approximately 1,000 new species of insects are published each year in the world, and they are included in the Zoological Record, making the journal a must-consult search tool for researchers working on animal taxonomy. Among the named insects, there are as many as 350,000 species of Coleoptera (beetles), of which the weevils are the largest, including more than 60,000 species, which is 10 times that of mammals. Lepidoptera (butterflies and moths) are next with about 200,000 species.

There are about 150,000 species of Hymenoptera (bees, ants) and Diptera (mosquitoes, flies). The figure below shows the relative number of known species of different taxa in the kingdom Animalia. Not only are there many species of insects, but there are also many individuals of the same species, some of which are surprisingly large.

An ant colony can have up to 500,000 individuals. A tree can contain up to 100,000 individual aphids. In forests, there can be 100,000 springtail insects per square meter.

When locusts occur in large numbers, the number of individuals can reach as much as 71.2 billion, the total weight is about 1,250,300 tons, and the area covered by swarms can reach 500,1,200 hectares.

Coal, an indispensable fuel for our daily lives, is the remains of these swampy forests that were buried into the ground by the earth's crust. Geologists named this historical period "Carboniferous".

In strata belonging to the late Silurian period 400 million years ago, scientists have found fossils of scorpions, a close relative of horseshoe crabs. It's very intriguing. Scorpions were likely the first animals to venture aboard land to breathe air.

Insects are almost ubiquitous on Earth, accounting for 80% of living animals. Not much evidence has been found about what their ancestors looked like, and when exactly they landed on land. But in the fossils of the Carboniferous period, people have seen many winged insects, among which there are thousands of species of cockroaches, and there is an ancient dragonfly with wings that are one meter long.

Whatever the connection between them and the scorpion landing, in the ancient swampy jungles, real insects have indeed appeared.