page_title: Decline in insect populations
section_title: Anecdotal evidence
hierarchical_section_title: Decline in insect populations / Evidence / Anecdotal evidence
caption_attribution_description: English: "Bug splats", Katoomba, New South Wales, Australia
context_page_description: Several studies report a substantial decline in insect populations. Most commonly, the declines involve reductions in abundance, though in some cases entire species are going extinct. The declines are far from uniform. In some localities, there have been reports of increases in overall insect population, and some types of insects appear to be increasing in abundance across the world. A 2020 meta-analysis published in the journal Science found that globally, terrestrial insects appeared to be declining in abundance at a rate of about 9% per decade, while the abundance of freshwater insects has increased by 11% per decade.
  Some of the insects most affected include bees, butterflies, moths, beetles, dragonflies and damselflies. Anecdotal evidence has been offered of much greater apparent abundance of insects in the 20th century; recollections of the windscreen phenomenon are an example.
  Possible causes of the decline have been identified as habitat destruction, including intensive agriculture, the use of pesticides, urbanization, and industrialization; introduced species; and climate change.
context_section_description: Anecdotal evidence for insect decline has been offered by those who recall apparently greater insect abundance in the 20th century. Entomologist Simon Leather recalls that, in the 1970s, windows of Yorkshire houses he visited on his early-morning paper round would be "plastered with tiger moths" attracted by the house's lighting during the night. Tiger moths have now largely disappeared from the area. Another anecdote is recalled by environmentalist Michael McCarthy concerning the vanishing of the "moth snowstorms", a relatively common sight in the UK in the 1970s and earlier. Moth snowstorms occurred when moths congregated with such density that they could appear like a blizzard in the beam of automobile headlights. A 2019 survey  by Mongabay of 24 entomologists working on six continents found that on a scale of 0 to 10, with 10 being the worst, all the scientists rated the severity of the insect decline crisis as being between 8–10. 
  The windshield phenomenon – car windscreens covered in dead insects after even a short drive through a rural area in Europe and North America – seems also largely to have disappeared; in the 21st century, drivers find they can go an entire summer without noticing it. John Rawlins, head of invertebrate zoology at the Carnegie Museum of Natural History, speculated in 2006 that more aerodynamic car designs could explain the change. Entomologist Martin Sorg told Science in 2017: "I drive a Land Rover, with the aerodynamics of a refrigerator, and these days it stays clean." Rawlins added that land next to high-speed highways has become more manicured and therefore less attractive to insects. In 2004 the Royal Society for the Protection of Birds organised a Big Bug Count, issuing "splatometers" to about 40,000 volunteers to help count the number of insects colliding with their number plates. They found an average of one insect per 5 miles (8 km), which was less than expected.
caption: Bug splats, New South Wales, 2009
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