Question
My outdoor holly bush has small white rectangular shapes on underside of leaves.  I thought it was paint at first but as I looked closer, that was not the case.  I washed off most of them then sprayed all with a soapy solution.  What can this be.

Answer
Good morning, Gilda.

Since you describe the insect as having a rectangular shape, I suspect that you have cottony camellia scales on your holly.  The link below will take you to a page with some images of this scale and you can compare to what you found on your plant.  We generally treat scales when the plants are dormant in the winter.  However, a product containing imidocloprid can be used in the fall.

Here's the link.
http://oregonstate.edu/dept/nurspest/cottony%20camellia%20scale.htm

Good luck with your plants,
Jen