British ladybirds and the harlequin ladybird threat

British ladybirds

It might come as a surprise to learn that there are 46 species of ladybird in the UK and 3,500 worldwide. Of our 46 three have been discovered in the last few years, the best known of these is the now infamous harlequin ladybird, first seen in 2004.

The commonest ladybirds in the UK are the familiar seven-spot ladybird (Coccinella septempunctata) which has seven black spots on its two red wing cases (see photo above) and the smaller two-spot ladybird (Adalia bipunctata), but there is some concern that these and other species of native ladybird will be badly affected by the spread of the harlequin ladybird.

The UK Ladybird Survey has a useful guide to the most common varieties of ladybirds in the UK.

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A ladybird is a beetle, so it has hardened forewings, or elytra, which form the distinctive protective cover for the abdomen and hind wings with which they fly. They are up to about 1cm long, quite rounded in shape and with brightly coloured, usually spotted, elytra.

The red and black attire of the ladybird is to warn predators not to eat them; ladybirds taste quite nasty so they are left well alone by other predators.

Visit our garden wildlife section for more about British wildlife

Why attract ladybirds into your garden?

As gardeners we have good reason to try to attract and look after these beautiful creatures. For one thing ladybirds eat aphids, plant lice and greenflies; one ladybird can eat thousands of pests during its lifetime of approximately one year beginning while it is still only a larva.

It is much better to have ladybirds on hand than to use chemicals to tackle pests, once we start using insecticides we upset the whole balance of nature, killing predators such as the ladybird as well as the pest species. Without any natural predators our gardens are wide open to attack from marauding insects so even more chemicals are needed and that is how the problem spirals out of control.

Find out about biodiversity in the garden

How to help ladybirds in your garden

To help ladybirds we should avoid using chemicals in our gardens and then provide them with suitable places to hibernate in the winter.

To hibernate they might look for evergreen trees where they tuck themselves away in cracks on the trunks; ivy is another popular location for the hibernating ladybird, particularly where ivy grows tightly around a tree trunk or even up against a house; a shed might also be used, particularly around the window frames where cracks provide security for these small creatures.

Find out how to make a wildlife-friendly garden

The lifecycle of the ladybird

The life cycle of our ladybirds typically consists of mating in the spring after which the females lay their eggs. The eggs hatch into black grub-like larvae which eat voraciously before pupating and transforming into the adult ladybird during the summer.

Ladybirds live for up to a year. They over-winter in adult form and mate in the spring. Eggs develop into larvae which in their early stages are very difficult to identify but they undergo four skin moults as they grow into successively larger forms, or instars, and in their later stages they can be identified using specialist guides and there are helpful photographs online, such as this guide to the most common varieties of ladybird larvae found in the UK.

By late summer ladybird larvae have moulted into their adult form ready to start the process over again.

Find out what to do about hibernating insects in your house

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An invasive Asian harlequin ladybird that was originally imported into Europe to control pests but is now out of control. Photographed by David Chapman.

The harlequin ladybird threat

You may have heard about a new species of ladybird which has started to spread quite rapidly across Britain.

The harlequin ladybird (Harmonia axyridis) is a native of eastern Asia, it has been introduced into many countries as a biological control against aphids but has spread rapidly. It was introduced to North America in 1988 and has quickly become the most numerous ladybird on the continent.

Its spread to the UK from Europe was probably by accident since it was first found in large numbers around Eurostar rail stations, and it is now reputed to be the fastest spreading non-native species in Europe.

Since the first sighting of a harlequin in 2004 it has spread rapidly throughout the south east of England and has now been recorded over much of England, parts of Wales and even into Scotland.

The spread of the harlequin ladybird is deemed to be the fastest of any invasive species in the UK and it is of concern because it is a faster breeder than our native species and, unlike our native ladybirds, it eats non-pest species, including the eggs and larvae of native ladybirds and the caterpillars of butterflies.

Harlequin ladybirds are very variable in colour. They are all quite large, about 8mm long and are quite rounded in shape. The most common forms in the UK are orange with 15 to 21 black spots or black with 2 or 4 orange or red spots. Their legs are almost always brown and they have white markings on their pronotum (the part of their body between the head and elytra).

We can learn more about identifying ladybirds and take part in surveys to improve our understanding of these species:

UK Ladybird Survey Website: www.ladybird-survey.org
Sightings of harlequin ladybirds should be reported to: www.harlequin-survey.org

Find out about citizen scientist projects around the country, including documenting invasive species

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