How to save a bug's life

The Independent 27 Jul 11;

Insects are Britain's most threatened – yet most overlooked – species of wildlife. But enthusiasts have devised innovative methods to ensure their survival, as Peter Marren reports

If you want to protect a bug, think small. That is the message to be gleaned from different plans to conserve Britain's most threatened species of small life, from large and colourful butterflies and dragonflies to the unsung hordes of hoverflies, beetles and spiders. It is all a matter of scale.

Whales have the ocean to swim in. Lions roam over territories the size of London. But an insect might depend on a solitary hole in a stump or live out its days in a puddle. And, perhaps surprisingly, some of these mini-habitats are in short supply.

More than a thousand invertebrates – more than all our animals, birds, reptiles and fish put together – are said to be in trouble. Without action to protect them we stand to lose such exotic sounding bugs as the Midas tree-weaver and the Golden hoverfly – not to mention the desperate-sounding Depressed river mussel.

As a signatory to the Earth Summit in 1992, Britain is committed to saving species, big or small. The lowliest snail or spider, we have decided, has as much right to exist as animals that engage our sympathies more, such as otters or water voles. But, in practical terms, saving species demands a lot of work. To start with, you have to find out why a small beastie is declining, and that in turn means understanding its way of life. And then you have to come up with the cash and co-operation to produce a workable plan.

Is it worth the bother? After all, few people would know or care if the Depressed river mussel decided to commit genetic suicide and disappear for good. Well, yes it is, says its most earnest champion, the charity Buglife. Human and insect lives are interdependent. "Bugs pollinate our food, clean our water and are crucially important to healthy eco-systems." They are like a tiny component in an aircraft. Small and seemingly insignificant, but take one away and the plane won't fly. Besides, Buglife reminds us, species are declining because of what we are doing to the landscape. In the end, it's not so much about biology as about us. Take away the Golden hoverflies and the Wormwood Moonshiners and it is we that are diminished and shamed.

Not all action plans work. But there have been some shining successes, and we seem to be getting better at it. Here are the best recent examples.

Ladybird spider: Eresus sandialatus

Easily our most beautiful spider, the male turns ladybird red in the last days of its short life, when it seeks, courts and mates with as many females as possible before dying of exhaustion. Its skin then becomes part of the wall decor in the burrow of its last suitor. The dead body of mother spider, meanwhile, becomes a handy first snack for her growing brood.

This is also our rarest spider, confined to a tiny patch of heath in Dorset. Fortunately enthusiasts have discovered a handy technique for rearing them inside plastic bottles. The bottle is then transplanted in suitable habitat, spider, burrow and all. Using spiders from Denmark, the Wildfowl and Wetland Trust has bred a large stock for release at its Martinmere reserve.

There are now more Ladybird spiders at large than at any time in the last century.

Hazel pot beetle: Cryptocephalus coryli

The odd life of this bright red beetle begins with its eggs, which the beetle coats generously with dung before flinging them into the undergrowth. The resulting maggots live inside this "pot", lovingly decorated with their own poo, and using their heads as lids. Despite this thrifty lifestyle, the Hazel pot beetle has fallen on hard times, and was feared extinct until a colony was discovered in Sherwood Forest in 2008.

Some of these have been bred on at Chester Zoo for release in likely pot beetle habitat.

Barberry carpet moth: Pareulype berberata

Barberry, a small, prickly hedgerow shrub, was all but ousted from the countryside by farmers, since it was the host of a damaging rust fungus that attacked crops of wheat. By the time rust-resistant crops of wheat were on the market, there were no more barberry bushes.

This was bad news for a little grey and brown moth, since its caterpillar fed on nothing but barberry. Fortunately it was saved at the eleventh hour by breeding captive colonies for release on newly planted barberry.

It has worked. With the help of Whipsnade Zoo, the moth has been re-established at numerous sites across southern and central England.

Golden hoverfly: Callicera spinolae

This handsome gold-fringed fly depends on rotting matter inside rot-holes on old, decaying trees. Its habitat is in short supply, which may be why it is restricted to a few parks and nature reserves in East Anglia. Fortunately hoverfly enthusiasts have found a way to boost its numbers without waiting for trees to grow old.

They tie plastic milk cartons filled with a porridgy mixture of water, wood mulch and leaf compost to branches. Mmm, hoverfly heaven.

Red click-beetle: Elater ferrugineus

The Red click-beetle is not only rare, but effectively invisible. Both the adult and its grub live deep in the decaying wood of mature oaks. The method used by beetle collectors of old by hacking into logs and stumps is no longer acceptable. Deborah Harvey from Royal Holloway College has pioneered a more subtle way of tempting the beetles by isolating the scent they use to find one another. Using it she has located the beetle in many new places, while, at the same time, elevating beetle spotting from a mere hobby to a science.

Giant oak aphid: Stomaphis quercus

All right, this giant is no larger than a coffee bean. But that still makes it the world's largest greenfly. Fittingly, it lives not on the stems of roses or tomato plants but on the trunks of mighty oaks. Here it is tended by a bodyguard of jet-black ants who kill or chase away any predators. Their pay-off is the sugary droplets of honeydew oozing from the aphid's bottom.

Despite its success at running a protection racket, the Giant oak aphid is rarely seen. Possibly it lives high up in the tree, whose height, scaled up to human size, would rival Mount Everest. Buglife has invited suitably athletic bug-hunters to take part in a Giant aphid hunt this autumn. Don't forget to bring your camera.

Mud snail: Omphiscola glabra

Mud snails look like tiny ice cream cornets. Despite its name, the snail needs clear, clean water, and that is its downfall – most of today's ponds are murky and far from clean. In a survey of 370 ponds in Cheshire the snail was found in only three.

Chester Zoo holds snail stock rescued from a pond that was about to go under concrete due to redevelopment at Manchester Airport. The plan is to release them into a new pond nearby as a "mitigation" measure.