Ladybirds
are pretty and charming creatures but most members knew little more about them until
a recent talk by Bryan Pinchen, who has written a reference book on them. There
are about fifty species of ladybird in Great Britain, around half of these are
tiny, the rest having spots and those were the subject of the presentation. Nearly
all of these occur in the New Forest. Bryan began by explaining the life cycle
starting with hibernation which is from October. The ladybirds often gather in
large groups frequently in exposed sites so they can keep an even temperature
to save waking up and getting cold - they can be active above 4°C but need 10°C to look for food. Food
and mating are the priorities when they emerge in the spring. The female lays
300/400 eggs spread around: one slide showed a female eating and egg laying
simultaneously - multi tasking! The
female dies after egg laying but the male lives on for further mating.
Most
species eat aphids, a few mould or vegetation. Aphids are very prolific
breeders but the ladybirds do not have it all their own way: some species of
ant will milk the aphids for honeydew and perhaps unsurprisingly do their best
to protect them from the ladybirds. The eggs hatch in 3-6 weeks. The larvae are
about 2mm growing to approximately 5mm. At this stage they are already showing
the colours of the adult and are eating 500 aphids per day!
The
larvae of the Scarce 7-spot ladybird are rather different, living in the nests
of wood ants and eating their pupae and larvae and some aphids which also live
in their nests. Far from attacking them the wood ants protect the larvae
because they have picked up the distinctive wood ant smell. After 6-8 weeks the
larvae pupate, often in exposed places, the pupae display colours to warn would
be predators that they do not taste nice. The adults emerge July/August and
feed up ahead of hibernation. Good hibernation sites will be used year on year
with one generation leaving a scent which attracts next year’s ladybirds to the
same spot. Different species are happy to share the same site. The hibernating
ladybirds do require a period of cold weather to become sexually mature.
Bryan
went on to discuss identification. Ladybirds are beetles and their hardened
wing cases meet in a line down the middle of their back, the wings folding neatly. Some creatures look
similar such as leaf beetles (which are related) dung beetles, cockroaches,
shield bugs, frog and leaf hoppers even though some of the latter are spotty
and black. There are subtle structural differences between all of them and
ladybirds. In this country there are only three species which are yellow with
black spots and of these the Harlequin Ladybird is the most frequently seen. It
arrived in this country in the year 2000 and spread very quickly along with
alarm that it would be a threat to our native species since it eats anything -
in practice it has not been a problem. Another species which arrived here at
the same time was the Bryony Ladybird. It was not regarded as a threat since it
is vegetarian; it has not been as successful as the Harlequin. The average
garden will support about ten species of ladybird; twenty of the twenty-five
species occur in mixed woodland and indeed many in most habitats but less on
heathland and in damp areas.