The term "entomology", which comes from the Greek, can be easily translated as the study of insects. The word insect on the other hand comes from Latin and means "notched". Because of their clearly segmented body, insects were also called "notched animals" in earlier times.
Insectology can be divided into general and applied entomology. Both areas are important and therefore also represented in the name of our society, even if this may seem a bit bulky.

General entomology

General entomology comprises the basic sub-disciplines of morphology (the study of shape), physiology (the study of life processes) and ecology (the study of environmental interactions) of insects. It also includes systematics, which according to modern view includes taxonomy, phylogenetics and evolutionary biology, which are concerned with the analysis of the relationship and ancestry of insects. Taxonomy, which deals with the determination, classification and re-description of species, uses data from morphology, supplemented by genetic methods such as DNA barcoding. Finally, entomofaunistics and biogeography, which are concerned with the identification of insects in specific ecosystems and the dynamics of their distribution, are also mentioned.

Applied entomology

Applied entomology comprises the subfields of medical entomology (entomological parasitology), forest entomology, and agricultural entomology. The latter two deal with harmful insects that threaten and restrict the cultivation and use of natural resources and food, and with ecosystem services provided by beneficial insects (natural antagonists of pests as well as pollinating species). In recent years, forensic entomology, which deals with the use of insects to solve crimes, has also become increasingly important and has repeatedly attracted public attention.
Among the entomologists organized in the DGaaE there are, on the one hand, professionals who earn their income directly from entomology, be it as employees in expert offices, industry or as collaborators at research institutions or authorities. The second group consists of amateurs or recreational entomologists. They usually have completely different professions or are retired and are engaged in entomological studies outside of their full-time working hours. The importance of this second group for entomology is immense, and many of the most important species experts and taxonomists of both sexes are located here.
Finally, entomology also offers the possibility of lay participation in so-called "Citizen Science" projects. Citizen Science can be carried out by voluntary individuals, groups or networks. These usually work together with professional scientists to achieve common research goals. Examples are the Mosquito Atlas, which has been recording the distribution of mosquitoes collected by laypersons for a number of years by sending them to us, or the large butterfly monitoring project.

Systematics and diversity of insects

In the 18th century, natural science in general experienced a remarkable surge in popularity. Many aristocrats, some of whom are now known as scientific pioneers, pursued natural science as a pastime. Princes considered it a matter of prestige to promote scholars and to have rich natural history cabinets, including insect collections. Added to this was the ever increasing influx of exotic exhibits from all parts of the world. With the Age of Enlightenment, the understanding of science changed.
The era of the apparent observation of nature by individual individuals had come to an end and the quantity of species had become confusing, so that attempts were made to gain an overview of the diversity of insects by means of appropriate systematization. Carl von Linné distinguished the insects in his work Systema naturae (Leiden 1735) mainly by their wings. At this time insect systematics was only based on individual external body characteristics (wings, legs, mouthparts) and was always insufficiently solved, so that it had to be re-investigated again and again. With his work Systema entomologiae sistens insectorum classes (Leipzig 1775), Johann Christian Fabricius, is considered to be the founder of systematic entomology as an independent science. His classifications were mainly based on mouthparts and lasted for half a century. The study of insect systematics has not yet been completed. Through transcriptome analyses, remarkable new insights have been gained and great progress made in this field in recent years (http://www.1kite.org/news.html).

Insects are the most successful animal group on our planet

But how do you actually measure "success" in an evolutionary sense? Here are some numbers:

Number of species (diversity)
Insects account for about two thirds of all existing animal and plant species, including bacteria and fungi. The last published exact number of insect species worldwide was 962,500 (2003). However, many more species have been described since then. About 80% of them belong to the "Big 4", the beetles (Coleoptera), Diptera, Hymenoptera and butterflies (Lepidoptera). In addition, many projections and estimated species numbers exist: They range from 2.5 million (Grimaldi & Engel 2005), 5 million (Gaston 1991) to 30 million (Erwin 1982). In total, about 100 million insect species have lived in the Earth's history, most of which have already become extinct. A species exists for about 5 million years before it becomes extinct again.

Number of individuals (biomass)
The worldwide number of insect individuals cannot be recorded. Approximations are possible by determining the biomass (weight). Example of migratory locusts (Schistocerca): A swarm can consist of several billion individuals that can cover several thousand square kilometres of land at the same time. About 10% of the animal biomass in the tropics are termites alone, which decompose 50–100% of dead plant biomass.

Evolutionary age
The insects have developed in parallel to the radiation of the first vascular plants (ferns). Science estimates the evolutionary age of insects to be about 480 million years. The winged insects have existed for about 410 million years (Misof et al. 2014). The holometabolic insects are about 240 million years old and lived already together with the first dinosaurs. They reached their greatest species diversity 100 million years ago by co-evolution with flowering plants (85% of all angiosperms are insect-pollinated).

Distribution
Insects have succeeded in colonising all terrestrial and aquatic habitats, with the exception of marine benthals and open oceans (one exception being the sea-skaters, Halobates spp.).

Conclusion

Insects are the most successful evolutionary group on our planet, no matter what indicators are used: they have the greatest diversity. They are the oldest land animals. They are the first colonizers of the air. They are the most widespread.
Special morphological, physiological and ethological adaptations have enabled them to colonize all conceivable habitats. With the exception of a few "border crossers", they were only denied a way back into the sea.