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Help, does anyone know what those white spots are? How do i get rid of them?

In my opinion, the spots are armored scale insects, insect family Diaspididae. There are several ways to fight them, but the only effective method in my opinion is the use of a systemic insecticide containing imidacloprid or a similar active ingredient.
You can also use alcohol and scrape the insects off the pads of your prickly pear cactus. I am not sure, if insecticidal soap would work, because the adult female scales do have a cover that protects them from chemicals applied externally.
There are forum members who know these chemicals better than I do.
For verification of the pest click on the tab above named "Pests and Diseases". The female Diaspis echinocacti scale cover is whitish gray and almost circular, while the males are smaller and elongate, as far as I recall with three longitudinal ridges on their backs.

Harald

hegar wrote:In my opinion, the spots are armored scale insects, insect family Diaspididae. There are several ways to fight them, but the only effective method in my opinion is the use of a systemic insecticide containing imidacloprid or a similar active ingredient.
You can also use alcohol and scrape the insects off the pads of your prickly pear cactus. I am not sure, if insecticidal soap would work, because the adult female scales do have a cover that protects them from chemicals applied externally.
There are forum members who know these chemicals better than I do.
For verification of the pest click on the tab above named "Pests and Diseases". The female Diaspis echinocacti scale cover is whitish gray and almost circular, while the males are smaller and elongate, as far as I recall with three longitudinal ridges on their backs.

Harald

Thank you