A few species feed on plants or mildew but most ladybirds eat aphids (greenfly) or scale insects. Both are garden pests and this is why so many people love to see ladybirds. The seven-spot ladybird can eat 5000 aphids during its year long lifespan.

No! The number of spots does not relate to age at all!

No. When an adult ladybird is formed, it stays the same size for the rest of its life. Humans have a skeleton inside their bodies, called an "endoskeleton", but beetles like ladybirds have theirs outside (an "exoskeleton"). This hard skeletal outside means that they can't grow any bigger.