Why do ladybugs have spots?

Ladybug spots

A ladybug's spots actually serve as a defense mechanism from predators. The spots, which can come in many different colors besides black, give the impression that the ladybug tastes bad, thereby keeping predators away. In fact, some ladybug species are even poisonous to smaller predators.

In addition, a ladybug's spots can be mistaken as eyes by its predators. This causes the ladybug to appear larger than it is, thus helping its survival.