Pest identification
What's eating my sempervivum montanum?
Mealybugs
Signs: White cottony clusters in rosette crevices; leaves yellow and shrivel
Control: Dab with 70% isopropyl alcohol on a cotton swab; spray with diluted neem oil; isolate affected plants
Vine weevil
Signs: Sudden wilting and collapse; C-shaped white grubs found in soil eating roots
Control: Apply pathogenic nematodes (Steinernema kraussei) to moist soil in spring or autumn; repot and remove grubs by hand
Fungus gnats
Signs: Tiny black flies around soil; larvae damage fine roots, causing slow growth
Control: Allow soil to dry thoroughly between waterings; use sticky yellow traps; drench with Bacillus thuringiensis var. israelensis (Bti)
Keep sempervivum montanum pest-free
Healthy plants resist pests best. Get the basics right:
Sempervivum montanum pests — FAQ
What is eating my sempervivum montanum?
Sempervivum montanum (mountain houseleek) is a tough succulent rarely troubled by pests. The main threats are mealybugs hiding in the tight rosette leaves and vine weevil grubs attacking roots. Overwatering encourages fungus gnats. Good drainage and airflow prevent most problems.
How do I get rid of mealybugs on sempervivum montanum?
White cottony clusters in rosette crevices; leaves yellow and shrivel Dab with 70% isopropyl alcohol on a cotton swab; spray with diluted neem oil; isolate affected plants
How do I get rid of vine weevil on sempervivum montanum?
Sudden wilting and collapse; C-shaped white grubs found in soil eating roots Apply pathogenic nematodes (Steinernema kraussei) to moist soil in spring or autumn; repot and remove grubs by hand
How do I get rid of fungus gnats on sempervivum montanum?
Tiny black flies around soil; larvae damage fine roots, causing slow growth Allow soil to dry thoroughly between waterings; use sticky yellow traps; drench with Bacillus thuringiensis var. israelensis (Bti)