What's eating my claret cup cactus?

Claret Cup Cactus (Echinocereus triglochidiatus) clusters into multi-stemmed clumps indoors, and the stems' interior joints are ideal hiding places for mealybugs. Scale insects also target the cylindrical ribs. Spider mites appear in very dry air. The clusters make thorough spray coverage essential — treat every stem, not just the visible outer ones.

White cottony masses wedged between clustered stems and in spine clusters; stems shrivel and lose color. Use a narrow alcohol swab between stems. Spray neem oil or insecticidal soap over all stems from all angles; repeat every 7–10 days.

Hard brown bumps on the rib surfaces of individual stems; sticky deposits and sooty mold in heavy infestations. Dislodge with a toothbrush and alcohol swab each stem. Apply neem oil spray and inspect the inner cluster stems carefully.

Silvery-gray stippling on stem surfaces; very fine webbing especially around the growing tips in winter. Increase air humidity, mist carefully, and apply miticide or neem oil spray every 5–7 days for three applications.