Where have all the insects gone?

There is a general view that insects are in serious decline - what’s the evidence for this?

Anecdotal data

There is plenty of anecdotal evidence about the decline of insects such as the much quoted lack of insects found on car number plates or windscreens. Kent Wildlife Trust has run a citizen science survey of bug splats over a number of years that supports this intuitive feeling.

There is also the feedback from anglers and ornithologists who informally monitor the same spots over many years.

You probably noticed that there didn’t seem to be many wasps around this year (2024). It is thought it was  a particularly bad year due to the cold wet spring and that populations may well recover next year but it’s a dramatic warning of what could happen.

Insect Armageddon?

Scientists are wary of headlines that suggest that insects may be heading for extinction. The consequences would indeed be devastating with the likely collapse of our terrestrial and freshwater ecosystems. The fact is however that there is very little data on insect numbers in large parts of the world and where there have been longer term studies they tend to be focused on a very small number of species.

The UK is a leader in insect monitoring

The UK however has some of the most detailed scientific evidence in the world regarding the decline in insect numbers. Here are some of the key studies

●      The UK butterfly monitoring scheme which started in 1976 involves a network of over 3000 sites that are systematically counted across the country during the summer. (see https://ukbms.org/). This suggests a decline in some species like the Small Tortoise Shell or the Wall Brown of over 50%.

●      The moth trap network managed by Rothamsted Research which has been running since the 1960s suggests an average decline of moths of about 30%.

●      The UK beetle recording surveys which cover species from carrion beetles to the ladybird survey (https://www.coleoptera.org.uk/home) and the the UK pollinator monitoring scheme (UKPoMS) started in 2017 also indicate population declines.

It is true that within this data there are also examples where there are species increasing in abundance and examples of colonists (species moving into the UK) so the picture is not straight forward but the overall narrative is significant decline.

A reminder of the situation is this year’s annual Big Butterfly Count which has recorded the lowest ever counts with the majority of species (81%) showing declines compared to 2023.