Ladybirds, also called ladybirds in America and lady beetles in Asia, are probably one of the most popular bugs on the planet. They’re little, brightly coloured and they don’t bite. Children, especially, love ladybirds. These insects are part of the beetle family and so aren’t technically "bugs" at all. Ladybirds feed not only on aphids, of which they are an avid predator, but on spider mites, mealybugs and the eggs of other insects. Much of their prey is harmful to plants, so ladybirds are well-liked by many gardeners. They have four distinct stages of life: egg, larva, pupa and adult.
Ladybirds mate in early spring. Under ideal conditions, a female ladybird may produce more than 1,000 eggs, but 20 or more over a period of one to three months is normal. They prefer to lay eggs near colonies of aphids for the immediate food source. Most of the time, unless resources are very good, some of the eggs are infertile and will become food for larvae. The ladybird’s eggs are small and clustered together for protection, often attached to the underside of a stem or leaf. Depending on the temperature, they hatch in three to 10 days.
The larva stage of ladybirds looks nothing like the adult stage. It is shaped somewhat like an alligator, rather than round like the adult, and is black with orange spots along its sides. It can eat up to 25 aphids a day, which is only half of what an adult ladybird can consume—but it's still quite a feast given its relatively small size. Larvae eat as much as they can for around a month before they’ve stored up enough resources to begin their transformation. That means it takes approximately 750 aphids to turn a larva into an adult.
In the pupal stage, ladybirds attach themselves to leaves. Each develops into something that looks like a large, fat caterpillar. The colour of the pupal stage depends on the species, but they range from dark colours that help the pupa blend in with surroundings to bright colours—oranges and reds—that warn away predators. At this stage in their development ladybirds are at their most vulnerable. They spend around 15 days hanging from the underside of leaves with no protection but their colouring.
When they emerge from their pupal stage, ladybirds are bright red or orange with black spots or black with red spots. These colours warn many predators away, and ladybirds can also produce a foul-smelling liquid and even "play dead" to keep the predators from attacking. Because of this, it is mostly other insects—such as the assassin bug or the stink bug—that eat them. Spiders and toads are also common predators of the ladybird.
Depending on the species, ladybirds may live up to a year after their pupal stage, a lifespan that many insects would envy. Many of the more common species live for around nine months, producing two generations a year.
Ladybirds hibernate in the winter, clustering together for warmth and protection in leaf litter, under rocks, in hedges or even in cracks and gaps in buildings. In the spring they disperse to lay their eggs.
Ladybirds are harmful to neither people nor buildings.