Up to 50% of all insects may have been lost since 1970 as a result of habitat removal, the increased use of pesticides, invasive species, climate change and light pollution. As many as 40% of the known insect species may be at risk of extinction. In the UK alone, the use of pesticides has doubled since 1995, and 23 species of wasps and bees became extinct between 1900 and 2000. The value of bees as pollinators in the UK is worth over £650 million, and globally at between US$ 235-577 billion (FAO). Certain species of butterflies have declined by as much as 75%. Specialist feeders, such as the spotted flycatcher, which feeds on flying insects, has declined by over 90% since 1967.
Insects are the most varied and abundant animal, out-weighing the human population by nearly 20 times. There are believed to be millions of insect species, of which about 50% are nocturnal.
Another study out-lined the risk of light pollution for insects. Artificial light at night is anthropogenic. Light has long been used by farmers to manage insect numbers. Light pollution now affects up to 25% of the world’s land surface. Moths, for example, mistake artificial lights for the moon. Vehicle lights in Germany kill an estimated 100 billion insects every Summer. Artificial light may prevent some insects (that use bioluminesence) from finding a mate.
Insect population crashes have been reported in countries such as Puerto Rico and Germany. Such declines could cause a major decline in the whole system, as food chains and food webs are disrupted.
Insect populations could recover if the use of pesticides were to be reduced and if more wildlife-friendly habitats were introduced e.g. urban gardens and parks. However, 70% of the UK’s land-use ifs farming, and the use of pesticides and land-use changes have been a double-edged sword for the country’s insects. Light pollution should be easy to reduce i.e. by turning off lights
More than 75 percent decline over 27 years in total flying insect biomass in protected areas – Caspar A. Hallmann et al., https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809