White spots on needles!

[brian]

Hello all,

I have a couple small outdoor cacti that have small, 1/8" max, white
"globs" affixed to the needles. They seem to be multiplying slowly, but I
can't see any source like ants. I can scrape the globs off, but it is tuff
to do as they are on there pretty well.

I have treated them with a spray that I have had some success with in
treating severe infestations of scale. Doesn't seem to help.

Any ideas?

brian