Because ladybugs have long been known to eat the gardener's pestilent aphids and other insects, there have been many attempts to use ladybugs to control these pests. The first attempt—and one of the most successful—was in the late 1880s, when an Australian ladybug (Rodolia cardinalis) was imported into California to control the cottony cushion scale. The experiment was expensive, but in 1890, the orange crop in California tripled.
Not all such experiments work. After the California orange success, over 40 different ladybug species were introduced to North America, but only four species were successfully established. The best successes have helped farmers control scale insects and mealybugs. Systematic aphid control is rarely successful because aphids reproduce much more rapidly than ladybugs do.