Thrips on roses
On roses, western flower thrips feed in the flowers: petals develop dark streaks and spots or buds deform and fail to open, and fragrant, light-coloured and white roses suffer most. The injury happens inside the buds before the blooms open, and cultivars whose sepals stay wrapped until the bloom opens have fewer thrips. UC IPM finds purchased predators unlikely to help in gardens, so leave the minute pirate bugs and lacewings already there to work. If young leaves and buds are bronzed and curled instead, suspect chilli thrips.
At a glance
- Damage
- Silvered scars, black frass specks, flecked petals
- Type
- Sap feeding · virus vector
- Settings
- Under glass, Field, Garden, Indoors
- Threshold
- No numeric threshold; UC IPM says thrips damage does not usually warrant insecticides in gardens
- Ally
- Orius insidiosus
- Rate
- No release: conserve the wild minute pirate bugs already in the garden (UC IPM)
How to confirm it
Tap flowers or shoot tips over white paper: slender insects under 2 mm that run rather than jump. Look for black varnish-like specks in the silvered patches. Naming the species for certain takes an expert with a microscope.
Identification, lifecycle, degree days and every control option are on the full Western flower thrips profile. Not sure it is this pest? Answer four questions about the damage.