The beauty of garden insects and how to help them survive

Adrian Higgins

THE WASHINGTON POST – I remember when people casually referred to all striped invertebrates as “bees”, when all insects were “bugs” and any such thing that buzzed in their vicinity required hosing with lethal poison.

Some people still see the insect world that way, no doubt, but I suspect the mass consciousness has shifted to a kinder feeling toward these creatures – and with it an understanding that most insects enrich the gardening experience.

And there are a lot of species. You will find fewer than 100 types of frog in North America, fewer than 1,000 bird species but more than 90,000 specific insects.

I know we have moved beyond the “bug” and “bee” stage because when I talk to people who are not passionate about gardening (poor things), they speak of a desire to put in a wildflower garden for the pollinators. By wildflowers, they mean native ornamentals, and by pollinators those two poster kids of beleaguered insects, the monarch butterfly and the honeybee. Whether native plants alone are the cure-all, or whether monarchs and honeybees are the worst off, are all matters open to debate.

But the underlying point is that even people who are not into gardening are thinking beyond fence-to-fence lawn and chemicals and about insects and long-flowering perennials. And it’s the insects that are drawing them into gardening, not the other way around.

The Mexican sunflower or tithonia is a tender annual that draws bees and butterflies in summer and autumn. PHOTO: THE WASHINGTON POST

There are insects none of us want, starting with the ones that want to snack on us – mosquitoes and biting flies, for example – and those that want to snack on our beloved plants. Legions of professional entomologists fret about sawflies, ambrosia beetles, scale insects and leafhoppers. But the home gardener can be more relaxed. When I realised my carrot crop was being attacked by grubs, I starting harvesting them in bulk and found different ways to consume them. The carrot soup was particularly good.

Even when the pests are unwelcome, you can still find them interesting and pretty. I am thinking of the harlequin bug (a real pest of kale), the hornworm growing fat on your tomatoes and even that bejeweled scarab, the Japanese beetle.

Other insects actually help the gardener, not just with pollination and fruit set but in killing off parasites. I have come to distinguish between the tiniest bees and wasps and consider it a thrill when a tiny, iridescent sweat bee lands on the back of my hand for a quick slurp.

As a class of organisms, insects are obviously successful – they were flying, crawling and swimming around this planet long before we showed up. So apart from the honeybee, the monarch and a few bumblebee species, it seems unlikely that insects would be in as much trouble as other life-forms or their habitats in the scary so-called Anthropocene, if only for their sheer numbers and species diversity.

But for years, reports have argued that many species are disappearing, and more recently there has been much talk of a dire collapse of the insect world, fuelled by some high-profile published studies.

A 2017 study in Germany recorded a 75 per cent reduction in the collection of insects, by weight, in 63 nature preserves in less than three decades. This year, a review of 73 scientific papers spoke of a decline so rapid that if it went unabated, insects would suffer a mass extinction. This spurred other scientists to pick large holes in the predictions, saying the findings and their interpretations were flawed.

What is needed, they say, is a better understanding of baseline populations that will give future declines more context. About one million insect species are scientifically recognised, but that is a fraction of the true number. Estimates range widely. A conservative figure is 5.5 million.

Matthew Forister, an ecologist at the University of Nevada, is among those who believe we can’t wait for complete insect tallies to protect them. He is the co-author of a new scientific review that argues that declines in insect diversity and abundance have been well demonstrated; in North America, 28 per cent of bumblebee species are considered threatened and 19 per cent of butterfly species are at risk of extinction.

Moreover, he told me, we know that climate change, habitat loss and pollution are harming animals and plants, and it is logical to assume that the mostly uncharted world of insects is imperiled too, especially when you consider that pesticide use on the planet has never been higher. The paper was written with Emma Pelton and Scott Hoffman Black, both of the Xerces Society for Invertebrate Conservation.

“This is similar to climate change and tobacco (its link to cancer) in that we have forces out there that want to make it more complicated than it is and say we don’t have the data we need to make a decision,” said Black, the society’s executive director. “We feel being paralysed by indecision will only make it worse.”

He said a few prescient voices in the 1980s were warning about climate change. “If we had taken action then we wouldn’t be in the situation we are now with climate crisis,” he said.

The authors are pushing for broad measures to conserve and protect insect habitats, including changing agricultural policies that reward ecologically harmful farming methods. Pesticides used for the cosmetic appearance of landscapes, parks and other green spaces should be banned. Managers of public green spaces, including highway edges, should establish insect diversity as a goal.

The beauty of insects, Forister said, is that it is in the power of virtually everyone to help them and the results are almost immediate. Plant a zinnia in a balcony container, and a butterfly will show up. Convert parts of your lawn into perennial beds, and pollinators will appear, your garden will be more interesting and beautiful, and your enthusiasm will spread to the neighbourhood, Black said.