I Think Something Is Bugging My Cactus

I never see anything more than an occasional gnat on my Peruvian Apple Cactus, but I am convinced that something is biting them as suspected by small spots. Another cactus has a white film on it. You can see both in my attached photos. Anything natural I can spray for bugs on cactus? I really never see them so I cant pick them off. Thanks!

The white film sounds like it could be mealybugs, they love hiding in the crevices where you'd never spot them. I've had luck dabbing them with a cotton bud dipped in rubbing alcohol, works better than spraying since cacti don't love getting wet.

Soapy water.
We use the most basic white washing powder, which is very common and cheap here in Mexico. Like the brand Roma. Mix that in some water and (carefully) slather suds on the cactus. Maybe consider wearing gloves.