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The first insects were landbound, but about 400 million years ago in the Devonian period one lineage of insects evolved flight, the first animals to do so. [1] The oldest insect fossil has been proposed to be Rhyniognatha hirsti , estimated to be 400 million years old, but the insect identity of the fossil has been contested. [ 3 ]
Globally, averages of these predictions estimate there are around 1.5 million beetle species and 5.5 million insect species, with around 1 million insect species currently found and described. [3] Between 950,000–1,000,000 of all described animal species are considered insects, so over 50% of all described eukaryotes (1.8 million species) are ...
Recent figures indicate that there are more than 1.4 billion insects for each human on the planet, [27] or roughly 10 19 (10 quintillion) individual living insects on the earth at any given time. [28] An article in The New York Times claimed that the world holds 300 pounds of insects for every pound of humans. [28]
These accusations were never proven, and modern research has shown that it is more likely that the insect arrived by other means. [1] The world did not experience large-scale entomological warfare until World War II; Japanese attacks in China were the only verified instance of BW or EW during the war. [1]
Insects — by country. Note: where an insect is found in a large number of countries on a continent, they are not categorized by each country — see/use: Category: Insects by continent . This is a container category .
The insects then act as a vector, infecting any person or animal they might bite. Another type of EW is a direct insect attack against crops; the insect may not be infected with any pathogen but instead represents a threat to agriculture. The final method uses uninfected insects, such as bees or wasps, to directly attack the enemy. [74]
Insect population decline affects ecosystems, and other animal populations, including humans. Insects are at "the structural and functional base of many of the world's ecosystems." [6] A 2019 global review warned that, if not mitigated by decisive action, the decline would have a catastrophic impact on the planet's ecosystems. [6]
Additionally 1702 insect species (28% of those evaluated) are listed as data deficient, meaning there is insufficient information for a full assessment of conservation status. As these species typically have small distributions and/or populations, they are intrinsically likely to be threatened, according to the IUCN. [ 2 ]