Across social media this year, there has been a sense of general dismay over the state of insects during the late spring, with many naturalists and entomologists noting that there seem to be fewer around.
So what exactly is happening with insect life? Are there actually fewer critters in our gardens this year? And what could this mean for the wider ecosystem?
What is the current state of insect life?
The sad fact is that we simply don’t know. We have a serious lack of data on long-term trends in insect populations worldwide. And, given the huge number of species, some estimate as high as 10 million, is perhaps unsurprising.
However, over the past few years, numerous studies have emerged that have tended to point in the same general, downward, direction. Of those insects we know much about, some are doing okay, but there are declines in well-known groups across the board, including butterflies, moths, dragonflies, some beetles and many bee species.
Declines can be measured in drops in abundance and in biomass (the weight of insects), diversity (the number of species present), or combinations of these.
To work out just how rapidly these species are declining requires long-term studies around the world, and many more people studying insects. However, both are in far shorter supply than we would like.
Is this only the beginning of a larger-scale decline?
Possibly. But we cannot currently say this with any sense of certainty.
Many entomologists currently suggest that the very hot and dry summer last year may be affecting insects, and this is certainly a good working hypothesis.
On the flip side though, some are reporting normal insect numbers in some parts of the country. To find out for sure what is happening this year we will need to wait for the combined data from long-term studies.
What we do know is that we are still degrading the natural world in many places, sometimes seriously so.
We can also say that, despite some improvements and success stories, the overall picture is not positive whether we are looking at insects, mammals, birds, fish, plants, or most other groups of living things.
However, we have proved to be very good at reversing declines when we decide we want to. Tigers, for example, have rebounded in India and Nepal, doubling their numbers.
A big issue with insects is that people are much less likely to care about them than they are about big charismatic mammals like tigers.
What is causing the decline?
Insects are extraordinarily diverse and live in a remarkable range of different habitats. It's not surprising then that there are different patterns, and different causes of those patterns, for various insect groups across the world. But we can nonetheless make some generalisations.
Habitat loss and degradation through human expansion and agricultural intensification are big players – water and soil pollution are important factors, and the use of pesticides can also impact some insects greatly.
Climate change can be more complex because some species can benefit from a warming climate and the rising levels of carbon dioxide in our atmosphere. But, on balance climate, it's looking like bad news for bugs.
However, climate change or not, be in no doubt that whatever the causes of the decline, we are to blame.
Why is insect life so important for the ecosystem and what effect is the decline having?
Insects are like 'ecological glue', binding the natural world together. They are found in almost all terrestrial ecosystems, often in high numbers, and are involved in virtually every important ecological interaction.
They are predators and prey, parasites, decomposers, nutrient cyclers, pollinators, seed dispersers, soil aerators and more besides.
When we start picking away at this ecological glue we risk damaging, or even destroying, the whole structure. In some cases, as with pollinators in some studies, we are seeing other species picking up the slack.
So, whilst we see a reduction in biodiversity, we don’t always see a reduction in function. Just how long a system can tolerate this kind of pressure is far from clear. Ultimately, it would be very unwise to assume we can keep getting away with the stresses we are placing on the natural world.
The notion that all insects will disappear is far-fetched. But the idea that we may end up with hugely depleted ecosystems that are unable to provide the 'services' we need – like pollination and nutrient cycling – seems far less far-fetched now than it did 20 years ago.
Over the coming years, it seems likely that we will see many more negative effects, and we’ll be getting better at detecting them. We might, hopefully, also become better at combatting them.
So, is there any way to combat the decline?
We can do things to slow down and even reverse the degradation of the natural world that we have caused. Let’s be honest, we have to because we rely on natural systems. But this will require us to think in more mature ways than we are used to.
We often talk about 'saving' a species, or being concerned about a particular group (like insects). Such an approach is great for awareness and fundraising, but it doesn’t fix the fundamental problem.
The reality is that we need to save their habitats – the places where nature can thrive. We also have to start thinking about the whole world as a habitat, not just the 'wild places' we see on nature documentaries.
Our towns and cities should be shared with biodiverse green spaces, interconnected with 'corridors' and dotted with ponds, tree stands and other features that support nature. Our agricultural practices need to change, allowing food production and nature to co-exist.
We also need to make use of technological advances that allow us to produce more food from less land, giving more space for nature.
We can do these things, but we have to decide that we want to do them at a societal level. Up until now, we have been children in a sweetshop when it comes to using the planet. The declines we are seeing in the natural world are a sure sign that it’s time to grow up.
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