Where have all the insects gone?

Save the bees

Insect Armageddon

The insect apocalypse is here

We are increasingly confronted with fearful visions of a world in which the tiny architects of the terrestrial sphere we call home vanish. Soil crumbles to dust; plants wither and bear no fruit, leaving holes in our harvest bounty: tomatoes, almonds, apples, cocoa – all banished from our diets unless painstakingly pollinated by hand.  

Likely futures are inevitably more nuanced than this; the evidence is complex and many insects have unexpected reserves of resilience. In temperate regions, they must of course survive considerable seasonal changes every year, and so we see the great pulse of insect abundance through spring and summer that draws migratory birds here give way to an apparent annual vanishing. It’s an ordinary occurrence, in that it has been taking place for hundreds of millions of years, and yet extraordinary to contemplate. Where exactly do they go?

Once those exhausted migrant birds have finished breeding and vacated the soundscape, it is some of our larger insects, the grasshoppers and crickets, which give the late summer voice. Their level of activity, and in some species the tempo of their song, increases quickly with temperature. Cool them down and they’ll slow until they stop altogether, yet bush crickets can be heard calling long into the autumn, carrying on a last-chance frenzy of complex courtship behaviours before the entire population is reduced to eggs. These are laid in the soil, or into the stem of a plant that’s been sliced open with the female cricket’s ovipositor, her egg-laying tool. Cricket nymphs appear soon after the eggs hatch in spring – tiny wingless versions of the adults. The Great Green Bush Cricket, by some measures the largest British insect, needs at least two winters for the eggs to develop and can continue pausing at the egg stage for as long as seven years until a promising enough spring comes. In summer this is a feisty species indeed – a fearsome predator that is liable to give a firm warning bite if roughly handled. Winter sees them reduced to mere specks, tiny parcels of source code and food from which the whole population must reanimate.

Many butterflies also pass the winter as eggs. The hairstreaks lay eggs like tiny flying saucers, each carefully positioned near a forked twig where fresh growth will nourish the hatchling in spring. What hatches from the egg is quite unlike the graceful winged creature that laid it, for – as we all know from The Very Hungry Caterpillar – butterflies undergo what is called complete metamorphosis. This ability to harness two very different body shapes, each appropriate for the tasks assigned to that life stage, is key to the success and diversity of many branches of the insect family tree. For hairstreaks, the caterpillars might feed for a month to six weeks – very hungry indeed; take a month or so to reassemble themselves into butterflies; and then spend just a couple of weeks as flying bursts of colour. The long wait as an egg – butterflies in potential only – occupies fully two-thirds of their year.

Some moth caterpillars do their feeding and growing inside autumn leaves, in what are known as leaf mines – I picture them with hard hats and a head lamp as they chew their way through – and some species have figured out, through co-opting bacteria and chemicals in their saliva, how to maintain ‘green islands’ in the leaf so they can continue to feed even when the rest of the tree is aflame with autumn colour. When finally sated, they’ll surface from their mine, drop to the ground and spend the winter sheltered in a cocoon nestled among the fallen leaves.

Elsewhere among the soil and litter, beetle larvae are active throughout the winter. Division of labour between the larval and adult stages in beetles is usually less strict, and adults may forage for the same foods alongside the next generation. The impressive Violet Ground Beetle can often be found hunkering down under logs in woodland, while its larvae, whose slender, segmented bodies lack the adults’ purple-edged wing cases but have similarly fearsome jaws and strong legs for running, hunt earthworms and slugs through the soil. The adults may live for several years, emerging to feed and mate when the going is good and sitting tight when the weather is too cool, or indeed too hot.

Other insect species that pass the winter as adults can be found in bark crevices, grass tussocks, plant stems, and sometimes in our houses – look out for green lacewings whose eyes have a beautiful rainbow shimmer like reflections in an oil puddle. Even some tiny, squishable, aphids overwinter as adults. Hardier than they look, adult aphids have been recorded surviving temperatures as low as –27 degrees centigrade, while those that pass the winter as eggs can be chilled below –40 and still hatch successfully*.

But the rate of attrition for all insects during winter is nonetheless high. A frost too far, washed away in flood debris, prised out of the soil by hungry birds and mammals, or perhaps unwittingly exposed by a gardener tidying up. Just as we expect and trust trees to re-green in spring, and flowers to emerge from bulb and root under the ground, we should keep in mind that the winter landscape is not emptied of insect life but would reveal, if inspected in minutest detail, many millions of small, still lives, seeds of the spring to come, and these too need to be nurtured and protected.

*Aphid facts gleaned from the late Simon Leather’s excellent Don’t Forget the Roundabouts blog: an entomological treasure trove.

Written for ‘Forest Church’ in the graveyard at St Michael’s Enborne, October 22nd 2023. Here’s the view looking south to Beacon Hill.

Swift Exit

This year we became homeowners for the first time. Everyone says how wonderful that must be and how happy they are for us, and while we will not miss renting, we mostly feel the weight of responsibility. I’m dubious of the idea that anyone can truly ‘own’ any part of the world; this house and garden has seen many lives and stories in its 114 years. We will look after it for a while, that’s all, before passing on. While my attempts to transform the garden into a wildlife haven are only just underway, it has already given enormous pleasure as a venue for wildlife watching. Top of the billing are swifts. Our neighbourhood of terraced streets is something of a swift city, and while I don’t have any year-on-year data, the local colony appears to be in good health. Our house is roughly in the centre of their domain, and on many evenings this summer I have found myself stood in the garden literally open mouthed watching them hurtle over my head.

After almost 39 years on the planet and having spent 15 of those watching birds ‘seriously’, I thought I knew swifts well, or that I at least had a good working knowledge of their flight patterns.  But I hadn’t heard the susurration of their wings at close range, or truly appreciated how batlike their flight can be at dusk. Their wings don’t simply ‘flap’ but appear to corkscrew as though the bird is powered by a propellor. Their speed and agility regularly left me gasping as they whistled past my ear, all but brushed the top of the garden fence and then rapidly gained height, all within about a second.

When, to our delight, we discovered that a series of investigative swoops in late spring had become an active nest by the first week of July, I realised that their breeding, too, was stranger to me than I’d thought. The nestlings’ begging chirrups rose in pitch and intensity over the next few weeks until they were joining the adults in full-throated screams. The frequency of feeding visits picked up through the middle of July, to the point that it only took a few minutes of pointing a camera to capture the video below. The summer wore on, cooler days followed the record hot spell, and no significant rain came. The nest seemed to go quiet, and I assumed perhaps they’d fledged. But the span of days from hatching to fledging for swifts is variable – the BTO gives a range of 37 to 56 days – and as far as we know they had hatched no earlier than the last week of June. Young swifts can use periods of torpor to cope with a slowdown in delivery of insects by their parents, and sure enough a few days into August I heard their begging calls once more.

Three birds appear to visit in this clip from July 16th. Not sure what’s going on!

At that point we began to worry, feeling keenly our sense of responsibility – these were our house guests, after all – but also our impotence, impossible as it is to conjure rain or the clouds of small insects that a damp spell might coax out of the ground. All we could do was watch the visits, listen to the nest and keep an eye on the garden for grounded fledglings, hoping the young birds would soon be following their neighbours on the long journey south. July’s screaming parties of tens of swifts were down to single figures, so this must have been one of the last local nests. We saw an adult visit on the 6^th, and after that saw and heard nothing more. They must have fledged when we weren’t looking. On the 9^th I saw eight swifts weaving over the local park, silently picking off what few insects they could. On the 10^th, nothing all day, until at dusk, while I was watering the garden, I saw a single dark shape whir over, appearing small and batlike again. I wasn’t sure, but the bird came back for a lower pass and once more there was that boomerang curve of a swift overhead.

Every day since, we’ve seen two to five swifts feeding over the houses. Usually, their departure feels sudden – they’re there and then they’re painfully, obviously not. This time it is more of a slow fade-out, perhaps reflecting other delayed nesting attempts, or perhaps it’s simply that I’m paying more attention this year. In this parched summer of global anxiety, with enormous crises impossible to fully conceive of, focusing my concern on a single nest of a single threatened species has been a form of solace. And yet it is impossible to look at a swift, these birds that are all flow, all connection, and ignore the global. I fear the final silence their departure will leave behind, just as I fear that, despite their apparent stability in our neck of the woods, the unravelling threads of the world will mean that one year they won’t be back.

More activity at the nest. Mid July, the young birds appear quite well grown.

In defence of conifer plantations

Conifer plantations. Nobody likes them; at least, few folk in the strange corner of Twitter I spend time in do. In terms of planting location and species mix, the majority of conifers are indeed ecologically and culturally alien. However, even in the gloomiest plantation the odd ray of light makes it down to ground level. Inability, or unwillingness, to even contemplate the potential upsides* of a land use we dislike strikes me as unconstructive. It’s also an easy way to guarantee a lot of very depressing walks in the countryside, because whatever our perspective I doubt there are many places we could walk for miles and find everything as it ‘should’ be. If we can’t see the beauty in contested, everyday landscapes, we must surely be missing many small opportunities for joy*. So, in hesitant defence of plantations, I offer three little views from travels over the last three years.

Firstly, this summer. Seen from Hadrian’s Wall, the small conifer plantations in Northumberland stand dark, tall and incongruously angular above the gradually unfolding ridge line. Unnatural, sure, but I enjoyed the way they add heterogeneity to the scenery, breaking the expanse of only sporadically species-rich grass. The arrival of both conifers and wind turbines, which also crown many high points in the interior of Northumberland, was much lamented by some, I’m sure, yet both add to the feel of a landscape that is worked. And the trees might be the only ones for miles around otherwise, adding some blessed variety to a day’s birding – crests and coal tits, siskins and redpolls, crossbills if you’re lucky**.

Three years earlier, in Galloway – some 75 miles due west from the wall – we walked up a steep slope into the heart of a larger plantation on the edge of the Galloway Forest. This vast artificially forested landscape is much enjoyed by recreational users who view the area with a less discerning ecological eye or, if I’m being more generous, a less curmudgeonly one, able to enjoy what is without losing sleep over what could be.

We were in search of what was once a closely guarded secret, and there is surely no better place to hide something than deep within the cool, lichen-draped underworld of a plantation floor. Now relatively well signposted paths lead to a small clearing, which protect the gently crumbling aviaries that served as a release site for red kites into Galloway about twenty years ago. The still atmosphere of the plantation feels like a semi-natural cathedral, with larch stems as pillars lining the nave, the clearing a sanctuary where the jumble of plywood and chicken wire forms a conservation shrine of sorts. Neither kites nor trees were self-sown and neither are universally welcomed (though the kites have more ‘right’ to be present, from a historic ecological perspective), but both now help to draw people to this quietly captivating part of Scotland that is still off the usual visitor trail.

Closer to home, a mixed plantation offered us sanctuary early this spring when we fled the house to avoid witnessing the destruction of a beloved willow in a neighbour’s garden. Great Pen is another Forestry Commission site, with a mix of native woodland and various colossal, planted conifers. An interesting mix of wildlife rubs along uneasily with the dog walkers and casual ramblers (like us), all drawn in one way or another to spend time among big trees. It is still a working plantation, and I ironically lament the growth of trees that have now shaded out habitat for tiger beetles and woodlarks. Hopefully, when the forestry operations clear another area, they’ll be back.

* There’s a practical argument in favour of planting conifers, too – and I mean proper productive forestry, not the straggly little squares planted for tax purposes in the 1980s which were probably what I was seeing in Northumberland – considering that the demand to cut plastic from packaging must ultimately lead to increased demand for forestry products, but that’s a whole other blog, and probably not one I’m qualified to write.

**As the Wildlife Trusts say, “Plantations can support species that would otherwise be absent from the landscape.” https://www.wildlifetrusts.org/habitats/woodland/coniferous-plantation