I have a house plant (believe it is some form of succulent) that has developed small brownish blisters over most of its leaves during the past week. See attached pictures. This occurred in two other plants of the same type over the span of 2 weeks. Both of those plants were located on a different floor in my home, and none of my other plants seem to be affected. I am unsure if this is some form of scale insect, a consequence of spraying the plant with an insecticidal soap last week, or possibly edema, which I read this morning can be a consequence of overwatering, insufficient light, or poor fertilization. If I scratch the bumps they pop resulting in sticky fluid leakage. Any thoughts on what this might be and whether it is treatable would be appreciated.

Your Orchid Cactus does appear to have edema. It also looks very wet. These plants are epiphytes, meaning they grow on trees or rocks in nature, so need a very fast draining potting soil such as a cactus mix with added perlite or pumice. Like all cactus and most orchids , they need to dry fast and almost completely before watering again.

does look like edema. Got to make that media grittier. No fertilizers for now. These epiphytes like good airflow around, so try to run a ceiling fan after watering to help with the dry out time if you grow them indoors. Or open a window weather permitting.

During summer time, these epiphytes love the outdoors. Even here, as hot and dry as we get into the triple digit range, it likes being outdoors, but have to be in shade and do frequent watering early in the day. It dries out fast anyways, so it will not suffer overwatering. But indoors, dry out times takes much longer, so the risk of overwatering is higher especially if the media is too heavy and dense.

Thanks both for confirming this is edema. I repotted the plant in 50:50 cactus soil and perlite this morning and will place it outside in a shaded area. I presume the damaged leaves will not return to normal, so hopefully better managing water can avoid a recurrence of the situation in the future.