Ladybugs for cottony cushion scale
The vedalia beetle, Novius (Rodolia) cardinalis, is the lady beetle that controls cottony cushion scale. Imported from Australia (Cornell dates it to the winter of 1888–89; UC IPM says the early 1890s), it controlled the scale in California within a year. UC IPM says no commercial insectary rears it, so the way to establish it is to collect beetles from another infested orchard or tree; as few as 20 will found a population. Imidacloprid does not kill the scale but is very toxic to vedalia. Bought convergent lady beetles are aphid feeders and will not do this job.
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 cottony cushion scale
- Vedalia beetleWild lady beetle — not sold · Wild — relocate 20 or more from another infested tree