Pests can be a big problem for cacti, and there are multiple kinds of bugs that feed on these plants. Common bugs are mealybugs, scale insects, spider mites, and cactus longhorn beetles. To prevent an infestation, use proper preventive practices like using pest control products on the roots. In some cases, like spider mites, you can wash them off with water. Just make sure you have proper coverage for the soil to prevent any direct contact with water. You can also use cotton swabs or a gentle brush to remove some bugs in hard-to-reach areas. And if an infestation happens, it’s better to put the plant in quarantine to prevent other plants from getting infected.