From BonsaiWIKI
Ladybug or Lady Beetles are predatory
insects that have an appetite for
aphids. The adults are recognized by their familiar hemispherical shape and their brightly colored shell. While adults do consume aphids, their young are even more voracious. Ladybugs can be purchased in bulk at garden centers for aphid control. The difficulty is keeping them around long enough to do some good. Release them in the evening after spraying some water around, and with luck they will stay for a meal and to lay a few
eggs
