Beetles may not be as pretty as butterflies or as buzzy as bees, but they play a vital role in every healthy garden, according to the RHS and The Wildlife Trusts, which are calling on gardeners to help these creatures for this year’s Wild About Gardens campaign.
With more than 4,000 beetle species in the UK, including ladybirds, ground beetles and rose chafers, gardeners need to provide a patch for them to encourage balance in the garden and boost biodiversity, campaigners urge.
Helen Bostock, RHS senior horticultural advisor and wildlife gardening expert, says: “Beetles were perhaps the first ever insect pollinator, being around in the age of the dinosaur and around a quarter of Britain’s beetles are thought to be involved in pollination.
“They do this by moving between flowers, picking up pollen on their bodies as they go, some of which drops off onto the next flower.”
Here Bostock picks five favourite beetles and explains what gardeners can do to support them…
1. Thick-legged flower beetle (Oedemera nobilis)
Often found on the flowers of daisies and brambles, especially in the south of England this is a bright green metallic beetle up to 11mm long. Only the males sport the wondrously swollen ‘thunder thighs’ from which it takes its name.
The larval stage feed within thistle stems, while the adults feed on pollen (not enough to cause damage) and nectar.
Action: Plant plenty of flowers to support them such as ox-eye daisy, buttercup and hardy geranium.
2. Devil’s coach horse beetle (Staphylinus olens)
If you stumble across a devil’s coach horse in your garden, you could be forgiven for thinking you have just had an encounter with a small black scorpion.
This is due to the defensive reaction this beetle has of arching its tail up over its head. They can also exude a distinctive odour when threatened.
Although there is no sting in the tail, don’t be fooled into thinking it is a softy. Emerging after dark, this fast and ferocious beetle hunts many other invertebrates and can give a human a painful nip if handled.
Rove beetles, of which the devil’s coach horse is Britain’s biggest, are predatory, notable for their short wing cases and long bodies. Many are black but some sport red wing cases, others are multi-coloured including blues and there are species that have yellow hairs.
The smallest species of rove beetle are less than 1mm long, but the devil’s coach horse is a heavyweight, coming in at 3cm long.
Action: Put out piles of stones for daytime cover.
3.Seven-spot ladybird (Coccinella septempunctata)
Many gardeners will be familiar with ladybirds, including this distinctive native species with its seven black spots on tomato-red background, but not everyone will have stopped to think that ladybirds are beetles.
Their shiny rounded shell is in fact a pair of protective wing cases (known as elytra and common to almost all beetles) which open when the ladybird wishes to fly to reveal a membranous second pair of wings below.
A ladybird has a huge appetite, munching around 5,000 aphids (greenfly and blackfly) in its year-long life. Both larvae and adults are predatory, helping gardeners keep down populations of aphids on plants such as roses and fruit bushes.
In winter, they have a charming habit of clustering together in large groups, huddled inside hollow plant stems. As with other native ladybirds, the seven-spot is under pressure from the non-native harlequin ladybird.
Action: Avoid sprays which could harm ladybirds.
4. Rose chafer (Cetonia aurata)
Chafers can get a bit of bad press. While Welsh and garden chafers can be to blame for damaged lawns, and summer chafers and cockchafers nibble a few plant roots in borders, other chafers carry out different functions in gardens.
The rose chafer is a rather fetching beetle. The adults, up to 2cm long, are copper-green with distinctive white flecks. Spot them in flowers such as roses and hogweed. Admittedly, they do feed as an adult on flowers and leaves but not to any major extent.
Their creamy-white grubs can be found in compost heaps, feeding on rotting vegetation, helping to break it down and recycle plant nutrients.
Elsewhere they feed on rotting leaves in hedge bases. They can feed for several years as grubs before pupating in the soil to emerge as adults in spring.
Action: Build a compost heap if you don’t already have one.
5. Sexton beetle (Nicrophorus vespilloides)
Sexton beetles offer an undertaker service for the corpses of small rodents and birds. The carcass acts as a ‘first date’ venue for males and females who can detect it with receptors in their antennae as quickly as an hour after death and from up to two miles away.
The pair can drag the corpse to suitable soft ground if required for they will begin to bury it in a shallow chamber. After mating, the female lays her eggs on the corpse.
This species of beetle is highly developed and the parent beetles stay on to care for the larvae, regurgitating food from the corpse in the first few days after the larvae hatch before the larvae are big enough to feed themselves.
The adults are chunky, up to 3cm long with black bodies strongly marked with irregular orange bands.
Action: Allow sexton beetles time to undertake their work if you stumble across a dead mouse or bird in your border.
The downloadable ‘Bring back our beetles’ guide and more information about the campaign can be found on the Wild About Gardens website wildaboutgardens.org.uk