Watch out for Croton Scale - Crotons, so flamboyant, varied and tropical are prone to infestation by mealy bugs and scale insects. They suck juices from the leaves with sharp mouth parts and then excrete “honeydew”, a sweet, sticky waste, which allows sooty mold (fungal) spores to settle and multiply.
Croton scale, so-called because the pest was first discovered at a nursery in Marathon on April 9, 2008, is an insect with a waxy protective coating that infects more than 75 plants in Florida including mango trees.
Although croton scale doesn’t cause heavy mold formation the insects are so small that formation of sooty mold may be the first sign of infestation along with ants that are attracted to the honeydew. Adult scales tend to be on the undersides of leaves and appear as slightly shiny ovals. I’ve had several large, old crotons with the scale and have managed to quell them by using a soft toothbrush dipped in rubbing alcohol to swab both sides of every leaf and using a Q-tip to clean the area where a leaf meets a stem. I combat the sooty mold with a spray solution of ivory dish washing soap diluted at .5 oz. to 1 oz. per gallon. I use rubbing alcohol on mealy bug colonies
Spraying with insecticidal soap is also a good way to deal with scale insects and mealy bugs. Make sure the one you buy is safe won’t harm beneficial insects and pollinators. Some plants may be sensitive to insecticidal soap so test by applying the solution to a few leaves and wait a day to see if the leaves wilt. Neem oil is also good and non-toxic to plants, birds, pollinators and mammals. Always apply products to plant surfaces late in the day or when it is overcast to prevent burning.