Ladybugs for magnolia scale
Penn State notes that the larvae and adults of certain lady beetles give some natural control of magnolia scale in late summer, and that pesticide applications may interfere. Treat them as a partner to a dormant horticultural oil spray in early spring, which UC IPM says has relatively little impact on natural enemies, not as a replacement. Control ants tending the honeydew, because UC IPM says they protect scales from natural enemies. Bought convergent lady beetles are aphid feeders and are the wrong insect for scale.
Before you act
Everyone's first idea for aphids, and the one beneficial where buying is usually the wrong move. The ladybugs sold by the tub are convergent lady beetles collected from the wild, and UC IPM says most fly away within a day or two of release, even when aphids are plentiful. The larvae do much of the eating, and they turn up on their own wherever there are aphids. How to recognise it, what it is confused with and how to keep it around are on the full Ladybugs profile.
Other controls for magnolia scale
No other reviewed control is listed for this pest yet.