Garden Pests and Diseases: nasty stuff making cactus stunted, 1 by james_botanist

james_botanist wrote:
Looks like cactus scale, Diaspis echinocacti (http://www.invasive.org/browse/detail.cfm?imgnum=5121069 ), a particularly destructive pest of cactus. According to an article in Acta Horticultura, Neem seed oil should do the trick. ( http://www.actahort.org/members/showpdf?booknrarnr=811_27 ). You should be able to purchase neem oil at most well stocked garden centers. I've used neem oil for other pests and all I can say is that it fairly effective but the smell and the mixing are not fun.

Cheers, Frank