What's eating my blue cereus?

Blue Cereus (Pilosocereus azureus) is most threatened by mealybugs, which hide in the areoles and wool-like trichomes along the ribs. Spider mites and scale insects also attack in dry indoor air. Inspect the blue wax-coated skin monthly; early removal with rubbing alcohol prevents colonies from establishing.

White cottony clusters in areoles and trichomes; stunted new growth; sticky honeydew residue Dab each cluster with a cotton swab soaked in 70% isopropyl alcohol; follow up with a diluted neem oil drench; repeat every 10–14 days until clear

Fine webbing across spines; yellow or bronze stippling on the epidermis; rapid spread in low-humidity rooms Rinse the cactus with a forceful stream of water outdoors; apply insecticidal soap spray; improve humidity slightly and avoid dusty conditions

Brown or tan shell-like bumps along ribs and areoles; weakened, discoloured growth above infested zones Scrape off individual scales with a soft toothbrush; treat with neem oil or horticultural oil spray, coating all surfaces; repeat monthly