Field Identification
The green caterpillar of the small white butterfly that drills holes in cabbage, kale, and nasturtium leaves and fouls heads with frass. Butterflies look innocent; your brassicas disagree.
Velvety green larva with faint yellow stripe along each side; adult is white with charcoal forewing tips (female has two spots). Caterpillars often feed openly in canopy interior.
How to Deal With It
Organic Control Methods
Bt kurstaki while larvae are small; spinosad for stubborn instars—hit undersides where eggs hatch.
Cotesia glomerata and other parasitic wasps frequently collapse outbreaks—mark parasitized 'mummies' and leave them.
Red undersurface varieties slightly reduce oviposition; till residues; time plantings between flights if monitored.
Floating row covers exclude adults; hand smash eggs and larvae in gardens.
Yellow sticky traps catch some adults; scout for netting damage on leaves.
Let Nature Handle It
Natural Enemies
- Cotesia glomerata
- Cotesia rubecula
- Birds
Threat Map