How to Make Mini Greenhouses for Root Cuttings, University of California Statewide Integrated Pest Management Program: Root Mealybugs, North Carolina State University Extension Integrated Pest Management Program: Root Mealybugs, University of Hawai'i Maona Extension: Root Mealybugs: Preventing the Serious Pests, Texas A&M Agrilife Extension: Growing Cactus, University of Hawai'i at Manoa: Mealybugs and Slugs, Tiny White Insects in the Soil of an Orchid. Root mealybug populations infest soil in nearby plants and lay eggs along the roots. An uncommon, but equally-effective beneficial insect is the mealybug destroyer, Cryptolaemus montrouzieri. Most Mealybug infestations come from already-affected plants, so always keep this in mind when increasing your plant-collection. Nymphs are most vulnerable before they develop waxy protection. Prolonged hot weather reduces numbers. Nymphs go through stages of 1st instar (45–71 days), 2nd instar (18–38 days) and 3rd instar (15–26 days). Mealybugs start out as eggs and then move into larval and adult stages. Distinguishing Symptoms. Adult mealybug destroyer lady beetle and its waxy white larva feed within a colony of mealybug nymphs.