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There has been considerable concern expressed during the last two years over the invasion into the British Isles by the Harlequin ladybird. Originally of Asian origin, it was introduced into Europe and America in 1988 as a pest control of greenfly and scale insect damage. It would not be fair to comment on the past examples of disastrous introductions of alien organisms under the umbrella of pest control. After all, in its native land its prey and its own predators and parasites will have reached a stable equilibrium and anyway, its only a ladybird. However, in America it is now their most numerous ladybird, far outnumbering the native species.
It is, in boxing terms, a coccinellid heavyweight, larger than most of our own 46 resident species. It is quite partial to the eggs and young larvae of our own 14-spot, 2-spot and 7-spot ladybirds. The illustrations show the wide variation of colour patterns. It has an additional advantage over our own coccinellid fauna in that some of our commonest species such as the 7-spot require a period of dormancy (diapause) before they can become reproductively mature. The Harlequins dont need that dormant period so that they can have two generations in a year. In regions with an extended warm season they have been reported as having up to five generations! Moreover, at a time when our own endemic ladybirds are hibernating, the Harlequin is still feeding.
I came across two fully grown larvae on the top of a headstone in Armthorpe churchyard in Doncaster in mid-October where they had been blown down from an overhanging sycamore. Additionally, in times of aphid scarcity they can turn to pollen and soft fruit. This is why Defra has now become involved. I am providing a more detailed article on the Harlequin in next months YWT magazine which will have photos. (These illustrations are from a pamphlet with no specified authors.)
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© Don Smith 2006.