Most biodiversity in the world is due to invertebrates and, especially, insects. Beetles are the most numerous of named orders and therefore major contributors to biodiversity globally, nationally and locally.

Identification and enumeration of most beetles and other insects is a skilled and time-consuming process therefore we have only a fragmentary knowledge of the ecology and diversity of invertebrates. However, ladybirds (Coccinellidae) are a small, easily found and identified family. They may be readily recorded by unskilled observers.

Furthermore many species of ladybirds are economically useful as predators of garden and farm pests (mainly aphids). Exotic species of ladybird are increasingly used commercially for indoor control of pests such as scales and whitefly. There is a possibility that such species could establish outdoors and compete with native species.

Findings

The survey started in 1999. There had been a massive collapse of most ladybird species numbers in the spring of 1998 so very few ladybirds have been seen. The most severely depleted species are the normally most common 2-spot and 7-spot ladybirds. These are major feeders on greenfly, blackfly and other aphid pests.

Numerous reasons have been suggested for this decline: increased parasitism or disease; reduction of the ozone layer; use of genetically modified plants; pollution; excessive use of insecticides. However, the most likely explanation is that climate change due to global warming has caused unusual periods of warm weather in the winter. Ladybirds have come out of hibernation too soon and been caught by spring frosts (as in 1998 and 1999) or starved to death because of the absence of aphids. Wet summers may also have contributed to mortality.

On the Bright Side…

Some ladybird species live on fungi or grass. These species seem to have been encouraged by the recent mild winters and wet summers. Indeed, the formerly rare Orange ladybird has had a population explosion in Epping Forest and now seems to be spreading throughout south-east England.

A new species to the country, the Bryony ladybird (it eats white bryony) has become established in Surrey since 1997. It has now crossed the Thames to Kempton and Hampton in Middlesex. It will, perhaps, soon appear further north wherever there is white bryony.

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