Leucanium scale insect on oak trees
Often mistaken for a disease, the leucanium scale is an insect pest that’s appearing in landscapes this spring.
You can easily rub them off the stem and when you do, a white powdery substance may appear, which is why many people think it’s a disease. The powdery substance can also be uncovered and seen on the stems.
These are the young scale insects, called the crawler stage. This is the stage at which they can be blown by the wind to nearby trees.