Monday, 19 April 2010

Invasive Species: Harlequin Ladybird

Red succinea morph of harlequin ladybird
Harmonia axyridis Pallas, 1773
Coccinellidae; Coleoptera; Insecta; Arthropoda
Hyde Park
October 2007

This is hopefully the first in a series of posts about species of animal and plant that are not native to the British Isles but have become an established part of the flora and fauna, at least in certain specific localities. Harmonia axyridis goes by many names: its most common name in the UK is the harlequin ladybird, because of its black, white, and red or orange coloration which resembles a clown’s make-up. Elsewhere, it is known as the Asian lady beetle, or Japanese ladybug.

A native of eastern Asia, and with close relatives in Australasia, the harlequin ladybird has invaded many other parts of the world, most notably North America and western Europe. It was introduced to North America as a form of biological pest control, but numbers quickly grew out of control. It was first found in the UK as recently as 2004, where it was first found in East Anglia. Since then, the spread has been rapid, reaching Scotland in 2007, and the species is now ubiquitous in the southeast of England. They are often a cause for alarm when large numbers congregate in sheds, outhouses, and even indoors during the autumn into winter, and as they become active once the weather becomes warmer, they make their presence known by flying around and bumping into windows. We have an invasion of harlequins at the Bruce Castle Museum where I work, in at least two of the rooms, one being a toilet.

Harlequin ladybird larva
Enfield, North London
June 2008

The lifecycle of the ladybird consists of four stages: egg, larva, pupa, and imago (adult). There are few people who can’t recognise an adult ladybird (identifying them to species is another story altogether though), but the larvae, looking so different to the adults in shape and coloration, are less well known. The eggs look like small orange balls, and the pupae like a smoothed-over version of a larva, often found stuck to a leaf, where its warning pattern of black and orange is enough to deter would-be predators.

Orange succinea morph of harlequin ladybird
Hyde Park
October 2007

There are three recognised colour morphs of the harlequin ladybird in the UK. The above photo is of the succinea morph, which has a red or orange background and many black spots. The spectabilis morph has four red spots on a black background, and the conspicua morph has two large red spots on a black background, Other morphs are present in the native and North American populations, but these are the only ones present so far in Britain.

Mating red succinea morph harlequin ladybirds
June 2008

The advice I was given a few years ago as to what to do if I found a harlequin ladybird (then quite a rare occurrence, I didn’t see my first one until 2006, I think) was to humanely despatch it. Usually that involves the heel of a shoe. I’m now seeing so many, and they are breeding so rapidly, that it’s proving impossible to do such a thing to all of them. Squashing a few ladybirds in the centre of the area they have spread from is hardly going to be effective.


Rita said...

Although they are an invasive species and have population explosions, do they do any actual harm to the environment?

Mo Hassan said...

The main effect the harlequin has on the environment is the fact that they are non-specific with respect to which pest species they target for prey. They obviously feed on aphids, but will also predate upon many other species of insects, including other (native) ladybirds, as well as soft fruit.