There are insects like black spots on the back of epiphyllum leaves. What should I do?

Pests and diseases, tortoise shells. Special insecticides can be sprayed, such as methidathion and chlorpyrifos, and scorpions will die. You can also spray washing powder about 500 times, 12 hours later, and then rinse with clear water to avoid affecting the breathing of epiphyllum. It is best to wipe with a soft rag for better killing effect.