What's eating my rhizomatous begonia 'cleopatra'?

Begonia 'Cleopatra' is an indoor rhizomatous houseplant susceptible to mealybugs hiding in the hairy leaf textures and along the rhizome, and to spider mites in low-humidity rooms. Fungus gnats breed in wet compost. Mealybugs are the hardest to eradicate and pose the greatest long-term threat to this plant indoors.

White cottony masses in leaf axils and along the rhizome; sticky honeydew and yellowing leaves. Dab individual bugs with a cotton swab dipped in 70% isopropyl alcohol; spray neem oil or insecticidal soap thoroughly, repeating every 7 days.

Tiny pale dots and a gritty feel on leaf surfaces; fine webbing in leaf axils in dry air. Raise indoor humidity; wipe leaves with a damp cloth; spray neem oil or miticide weekly for 3–4 treatments.

Adult flies hover around soil; larvae damage fine roots in perpetually moist compost. Allow the top 2 inches of compost to dry between waterings; use sticky yellow traps; drench with Bacillus thuringiensis israelensis (Bti).