What's eating my pygmy cactus?

Rebutia pygmaea is a small clustering cactus prone to mealybugs lodging between offsetting heads and in tight spine clusters. Root mealybugs are the most serious threat given its compact root system. Overwatered plants also attract fungus gnats. Good airflow and a very gritty, fast-draining mix are the primary defenses.

Cottony white fluff tucked between clustering offsets and in areoles; weakened, discoloured growth tips Use a fine brush or cotton swab with isopropyl alcohol to reach between heads; repeat weekly for a month

Cluster offsets wither or roots fail to establish; white mealy powder on roots when plant is unpotted Bare-root the plant, destroy all soil, soak roots in neem solution, allow to dry and repot in fresh mix

Larvae damage fine feeder roots in wet soil; adults are a nuisance flying near the soil surface Top-dress with perlite or coarse grit to keep the surface dry; use yellow sticky traps; water with Bti solution