Harmonia axyridis Pallas
First recorded in the UK during 2004, by August 2006 more than 3500 sightings of this highly invasive species had been recorded. Although a south east asian ladybird it was introduced to Europe and the USA to control aphids and cossids on various crops but as far as is known it was never deliberately introduced into the UK. The species is thought to have arrived here from two sources; by direct flight from Europe and with imported foodstuffs from both Europe and America (Ware et al.).
Although a voracious aphidophage, outcompeting other species for this food source, it will also take a wide variety of insects so having a detrimental effect on other ladybirds both by competition and direct predation of early stages. When insect food becomes scarce it will feed on fruit, having a detrimental impact on fruit and wine production abroad. The Harlequin continues to spread throughout the UK and is thought to represent a serious threat to our native species.

The insect is found throughout Watford, with sightings for every week during the winter of 2006/7, specimens have been found singly under bark etc. and we know of several large hibernating colonies. During the late summer of 2006 the species was very common around Watford town centre.

A large species, at least 6.5mm but normally around 8mm and very variable in pattern, some forms may be overlooked as Coccinella 7-punctata but immediately recognised by the elytral sculpture, the convexity being interrupted subapically by a transverse tuberculate ridge.

Ware, Majerus, Roy, Symington 2005. The Harlequin ladybird arrives in Britain. Bull. Amat. Ent. 64;175-186

A summer has passed since writing the above and we feel some update should be made to our summary of the species local occurence. H.axyridis was active in small numbers throughout the winter of 2006/7 in all habitats throughout Watford. Pupae were observed from April and by this time the adults were common, as were other species of ladybird. They remained common until mid July when numbers seemed to increase, this continued into August when larvae, pupae and adults were abundant everywhere. This abundance has persisted into, and it seems increasedinto, late October. On the weekend of 20/21 October 2007 they were present in large numbers throughout Cassiobury park e.g. each rubbish bin hosted numbers of larvae, pupae and adults. During this weekend we swept a single 7-spot, the first specimen we had seen for about 6 weeks. H.axyridis are now,24/10/07, everywhere and in large numbers, more alarmingly perhaps, they are still emerging from pupa despite the recent drop in temperature.