Scale on staghorn ferns
How do I treat my fern for scale ?
Certified GKH Gardening Expert
There are many ways, organic and not, that you can control scale bugs. Neem oil is always a good choice, if you are concerned with how the plant will react to treatment, as it is very gentle on plants.
Here is an article with more information: https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm