Question

Staghorn   I live in the tropics and have 3 staghorn ferns.  2 are outside of the house and a third is in an interior garden room that is open to the outdoors and gets indirect light.  The plant that is by itself has short white lines at different places underneath the leaves.  They are close to half an inch long and an eight of an inch wide.  They don't seem to be moving.  They are a bright, chalky white and all seem to be the same size.  The leaves look healthy and I want to be sure they will stay that way.  The two plants in the front do not have the same spots.  What is causing the spots?  Are they injurious to the plant?  If they are, what shall I do about them?  Thank you.

Answer
Ellie hi;

Thank you for the picture and great question.

Without some close magnification, I cannot supply a definitive answer.

However, I believe I can say with great certainty that you have a very minor infestation of mealybug or scale (again, I would need great magnification to identify the exact pest).

In both cases, the infestation is very minor.  If left untreated, it may eventually develop into a more severe issue.

I would recommend trying to wipe or peel them off with a smooth cloth dipped in a mix of water and dish detergent (say 2 TBS detergent in a cup of water).  If they do not peel off easily, the detergent will (most probably) kill off the bugs and prevent further infestation.

You may wish to continue scouting for similar or other pests every 3 months or so.  As long as the problem is minor, you can continue to clean in the same manner.  If this becomes a severe infestation, you may wish to consider other options (but, from what I see, it is very unlikely that this should become serious).

I wish you the best and hope I have been able to provide adequate guidance.

DC