Un-ladylike Ladybirds!

IN the late 1880’s, the citrus orchards which produced California’s worldfamous oranges were devastated by a plague of aphids and scale insects. The biggest natural enemy of the aphid is the ladybird beetle. The California fruitgrowers introduced ladybirds in their orchards. Within a few weeks, the number of aphids decreased dramatically. Since then, the farmers have been buying ladybirds by the litre (there are around 10,000 of these colourful bugs in one litre)!

Ladybird beetles are believed to have acquired their name during the Middle Ages when they were associated with the Virgin Mary and were called ‘beetles of Our Lady’. They are among the best-loved of insects, because adult ladybirds are very attractive to look at, with rotund bodies in brilliant red, orange and yellow spotted coats. They also feed voraciously on insects which we want destroyed!

The female ladybird lays her eggs close to thriving aphid colonies, so that when the larvae emerge, they have food close at hand. Ladybirds lay their eggs underneath leaves. Some may disguise them with a layer of their own faeces. Aphids of all ages spend much of their time with their mouthparts embedded in plant tissue, sucking up the sap. The young ladybird larva has no trouble in seizing the first aphid of suitable size that it comes across. The aphids are utterly defenceless. An adult ladybird beetle may eat around 800 aphids in a single day!

One species, the dwarf ladybird, lives among the samurai, a species of aggressive Japanese aphid. It mimics the aphids’ appearance so well, right down to its dull grey colour, that even the watchful soldier aphids ignore it. The dwarf larvae move freely in the aphid colony, devouring their hosts!

Ladybirds range from 2.5 mm to 13 mm in length. There are around 5000 species, one of the most numerous in the insect world. Many species have wings. Ladybirds move slowly and since they are so conspicuous, they fall easy prey to insect-eating animals. They defend themselves when alarmed by releasing drops of a red, sticky, bitter-tasting liquid from their mouths and from pores at their joints. The caustic flavour repels attackers and gives the ladybirds enough time to escape.