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A DREADED invasive insect, the harlequin lady beetle, has become established in South Africa, and it is rapidly spreading through the country. It carries the scientific name Harmonia axyridis and in South Africa is known as the 'harlequin lady beetle' or, for short, 'the harlequin'. This insect, originally from central and eastern Asia, has in recent years become one of the world's worst invasive, harmful animals.

The beetles were recently spotted in Somerset West by a local gardener (who does not want to be named), who says Somerset West is a new red pin on the map.

"As for control or eradication measures, I am afraid there is very little I can tell you. Presently, there is no specific control measure that can be recommended against the harlequin lady beetle.

"While we are only but just starting our research in South Africa, colleagues in the Northern Hemisphere has been investigating the 'harlequin phenomenon' for several years already, but no pest control measure besides common sense has yet been coming forth. This is a big problem.

"One should, at this stage at least, and particularly out-of-doors, certainly not treat the 'harlequin' with any pesticides, as any insecticide which would kill the 'harlequin' would almost certainly also kill any indigenous, beneficial lady beetle species (of which South Africa has more than 300). Moreover, one should be very certain that you actually deal with the real McCoy, as there are several look-alikes." He initially noticed these beetles in the spring of 2004, but only in the summer of 2006 specimens were sent to the South African National Collection of Insects in Pretoria, where they were conclusively identified as Harmonia axyridis.

Field observations lead to the conclusion that the harlequin was established and reproducing at Riviersonderend. The die was cast.

Lady beetles (= ladybird beetles) (family Coccinellidae) are widely considered beneficial insects and a symbol of good luck. Few insects are treasured so much by so many cultures.

The harlequin, however, has some very nasty habits.

Like many lady beetles, the harlequin preys voraciously on aphids and other soft-bodied arthropod pests.

It was for this reason considered a valuable biological control agent for a long time, and there was significant trade in these beetles in some countries (not South Africa). They were repeatedly released as biocontrol agents in the USA and Western Europe.

The harlequin's appetite is, however, not satisfied by pests alone. They willingly feed on immatures of various non-pest arthropods, including beneficial kinds. They even feed on other lady beetle species, including indigenous and beneficial ones.

They even feed on each other. They are very effective in their voraciousness, outcompeting resident lady beetle species, which may decline, leading to ecosystem disruption.

Then the harlequin may move on to feed on pollen and fruit.

Harlequin individuals present among harvested grapes may taint the vintage with an exotic bouquet of rancid peanut butter, rotting spinach, blue cheese or sawdust!

Then the harlequin moves into your house, forming large, unwanted overwintering aggregations.

Handling them may lead to them secreting a noxious fluid which may stain walls and fabric. And - injury upon insult - the harlequin can be bad for your health!

It appears if the local populations of the harlequin are mostly still small, and at some collecting localities the species might not yet actually have established yet.

There is international interest in this phenomenon, and the harlequin is seen as a 'model species' of invasion biology and of biocontrol that went crooked. At the forthcoming International Congress of Entomology (Durban, July 2008) a whole symposium will be dedicated to this nasty beast.

Recognising the harlequin
The harlequin lady beetle is extremely variable in colouration, but it can readily be distinguished from other lady beetles in South Africa. Adults are 5-8 mm long and 4-6.5 mm wide.

The body is strongly convex, subcircular in outline, glossy and hairless.

The ground colour of the upper side ranges from yellow through orange to red, with zero to 19 black spots.

The lateral surfaces of the pronotum bear yellowish-white oval areas. A transverse ridge is usually present above the elytral apices.

This combination of characters does not occur in other South African lady beetles. Black forms of the harlequin are known from other parts of the world, but these have not yet been seen in South Africa.

The arrival of the harlequin in South Africa presents an uncommon opportunity to study the pattern of a biological invasion virtually from the start. Ideally, a structured survey of the spread of the harlequin through South Africa should be launched, but a pervasive lack of manpower rules that out.

Instead, citizen science can be mobilised: anybody finding, anywhere in Africa, any number of harlequin lady beetles - or lady beetles suspected to be the harlequin - is urged to collect the beetles and contact Riaan Stals at the South African National Collection of Insects (StalsR@arc.agric.za).

Just collect the beetles in a clean vial and pop them into the freezer. Arrangements will be made when you contact Riaan Stals. Clear photographs are also very welcome

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