Scale until recently was only a problem on my orchids. Lately down here in Houston it has become an outdoor problem as well. I wish it was as easy to fix on trees as it is on houseplants.
Scale is a group of insects that feed on plants. You’ll notice them on your houseplants as hard bumps about an 1/8″ to 1/16″ across and usually dark brown. They don’t move or look like bugs. Usually plants will have sticky areas along the leaves as well.
Scale can also be white and long, thin bumps. However, I’ve only seen these scales outside.
Scale insects suck the sap out of your plant.
Because of their protective shell the only time spray on insecticides help is when they are first born and crawling to the location where they will build a shell over themselves.
Luckily houseplants are small and I’ve found that placing the infected plant in the sink, washing the leaves with soapy water ( ~ 1 tablespoon dish soap to a gallon of water ) will remove all the scale.
I then follow up with an insecticidial oil spray.