To avoid avoid introduction of pests, quarantine and treat all newly acquired Haworthias before bringing them into the collection.
For a new plant, clean as much of the growing medium out of the roots and completely discard it. Some roots may be torn off but the plant will be fine. Treat the plant with potassium fatty acids soaking and then hydrogen peroxide soaking, rinsing it after each soaking round. This kills any pests and fungus. Hydrogen peroxide also promotes faster healing of any roots that were damaged. Let the plant dry out in a shaded place before planting it in a fresh growing medium, and prioritize the application of Imidacloprid in subsequent waterings.