Insect season – how to find out about insects

Summer is the high season for insects. A hot summer’s day just wouldn’t be the same without that reassuring hum as they go about their busy lives. Yet they are disappearing at an alarming rate and we could all find out more about them in order to save them. Cornwall Wildlife Trust is part of a national campaign to highlight the problem. www.cornwallwildlifetrust.org.uk

• How can I find out about insects of Cornwall?
• Why are insects declining?
• How do I discover insects near me?

Find out about insects the easy way – by going outside and watching them. It’s easy to appreciate butterflies and bees, but I like to take a closer look at the other six-legged creatures that share our countryside. Whether wasps, craneflies or beetles, each has an important role to play in nature’s complex, interwoven ecological webs. Most have fascinating life cycles and, when viewed very close up, have an astonishing and perhaps monstrous, while strangely beautiful and often highly colourful appearance.

Around 95% of all animals on Earth are insects. Whether we love them or not, insects are worthy of our respect, for we ultimately depend upon them for our own survival.

Insects in Cornwall

At my home in East Cornwall I score quite highly on the splatter test: a host of intricately delicate flying masterpieces meet a sudden and unfortunate end as sticky marks on my numberplate, headlights and windscreen.

However, with the rapid loss of habitats such as unimproved, weed-filled rough grasslands, UK insect numbers have dropped dramatically, and even Cornwall has suffered significant losses.

A classic example is the large blue butterfly, which depends upon both wild thyme and a particular red ant. Once the emblem of Cornwall Wildlife Trust (then the Cornwall Trust for Nature Conservation), the large blue was last seen in Cornwall in 1972 but survived on Dartmoor in neighbouring Devon until 1979.

Reintroductions of a subspecies of this butterfly from Sweden to sites in South West England have proved successful, but the original UK subspecies has gone forever. I cannot help worrying about less glamorous insects which are dying out completely unnoticed in Britain and all around the world.

Why are insects declining?

The weather plays a crucial role in insect mortality. Spring heatwaves can dry out shallow ponds and streams, making the flamboyant dragonfly a less familiar sight, while overcast, wet summers cause emergence from nymph to adult to fail. Wet weather hits bees, wasps, butterflies and moths hard, and international weather patterns affect migratory species.

Light pollution can adversely affect vulnerable wonders such as the glow-worm (Lampyris noctiluca), while the hedge flail has caused widespread insect losses, destroying overwintering adults, eggs and larvae.

Half a century ago, the air above our waterways shimmered with vast swarms of mayflies, caddisflies and stoneflies, providing bountiful meals for fish, amphibians, reptiles, bats and birds. I still see these insects in Cornwall, along with little airborne dancing troupes of midges, mosquitoes and gnats, but populations have declined throughout Britain. Agricultural run-off, pesticides and herbicides have contributed, while the decline in highly mobile insects such as bees, which might be taking a harmful pesticide cocktail on board as they travel across the countryside, is a source of debate.

Insect discoveries

‘New’ insect species are being discovered every year, but before you can be sure that you have found something as yet unclassified, it is best to familiarise yourself with your local species. Potential insect enthusiasts should go out on a hot, dry summer’s day and spend a while adjusting their eyes to the fine detail of the world they step upon. It is utterly absorbing!

On local heathland in my part of the South West, I look out for the green tiger beetle (Cicindela campestris). In flight it is a nondescript blurr, but when it settles it shows off metallic-green wing cases peppered with tiny spots.

Along streams and rivers I look for the beautiful demoiselle. The male is iridescent blue and the female iridescent green. Both have striking dark wings, the male’s becoming bluer with age. While looking, I start to notice a number of other damselflies, ranging in colour from delicate and subtle to dazzling.

Out wildlife watching with the youngsters

My children and I have often gone grasshopper spotting in grassy woodland glades or old mine sites with fine grasses. Crickets also chirp in the bushes. Our rasping friends are not so easy for older people to hear, so young people can act as chief listeners, while expressing incredulity at the inability of the more mature among us to hear such obvious sounds).

If we share our wildlife discoveries with the younger generation they need never be bored on a fine day again. If they grow up uninformed and disinterested, then all may be lost for some of our most useful and beautiful six-legged friends, and ultimately for us humans too.