What's eating my astrophytum coahuilense?

Astrophytum coahuilense, a flocked bishop's cap cactus, is prone to mealybugs hiding under its white trichome dots and root mealybugs below soil. Scale insects can appear on the ribs. The woolly white surface coating makes early detection hard — inspect the growing point and soil surface regularly under good light.

White cottony masses partially camouflaged by the plant's own white flocking; growth slows and the body may yellow Use a hand lens to identify true pest colonies; treat with 70% isopropyl alcohol on a fine brush; follow with neem oil spray; repeat every 7–10 days

Wilting and failure to plump up after watering; white wax coating on roots and inner pot when unpotted Unpot, wash all soil away, soak roots in imidacloprid drench for 20 minutes, dry for 3–5 days before repotting in sterile gritty compost

Small, hard, brownish lumps adhered along the ribs; dulled appearance; sooty mould where honeydew accumulates Pick off with a soft toothbrush or cocktail stick; apply neem oil or horticultural oil; repeat after 14 days