Why should we be concerned about the arrival of the
Threat to wildlife -
Harlequin ladybirds can seriously affect native ladybird
- Harlequin ladybirds are very effective
aphid predators and have a wider food range and habitat
than most other aphid predators (such as the 7-spot
ladybird) and so easily out-compete them.
ladybirds do not have a requirement for a dormant
period before they can reproduce, as some ladybirds
have (e.g. 7-spot and eyed ladybirds), and so have
a longer reproductive period than most other species.
In 2004 in London, harlequin ladybird larvae were found
still feeding in late October, long after all the native
species had sought overwintering sites.
aphids are scarce, harlequin ladybirds consume other
prey including ladybird eggs, larvae and pupae, butterfly
and moth eggs and caterpillars.
ladybirds can disperse rapidly over long distances
and so have the potential for rapid geographic expansion.
Problem to humans -
Harlequin ladybirds have a tendency to aggregate in
buildings in large numbers during autumn and winter.
- Many people find harlequin ladybirds a
nuisance in the house, and do not wish to share their
home with a few tens of thousands of harlequins
a defence mechanism many ladybird species exude a yellow
fluid (called reflex blood) which has an unpleasant
acrid smell, and which can stain soft furnishings
hungry, harlequin ladybirds will bite humans in their
search for something edible. Ladybirds in houses, woken
from dormancy by central heating, may bite people as
there is no food available. The bites usually produce
a small bump and sting slightly. There are a few documented
cases of people having a severe allergic reaction to
Harlequin ladybirds damage soft fruit
Harlequin ladybirds are also particularly fond of grapes,
and wineries are finding large numbers in the grape harvest.
These are difficult to separate from the grapes before
pressing, and the defensive chemicals (reflex blood) produced
by the ladybirds taint the wine.
- In late summer, when harlequin ladybirds
are feeding up for the winter, they will seek ripe
fruit and suck the juice from it to gain sugar. They
thereby cause blemishes on late summer ripening fruits,
such as pears, and reduce the value of the crop.