Field Identification
A gray-green, waxy aphid that colonizes brassicas—cabbage, kale, broccoli, cauliflower, mustard, arugula, and many wild mustards. Dense colonies hide in crown and heart leaves, causing stunting, leaf curl, and contaminated heads slick with honeydew and sooty mold. Present wherever brassicas grow from cool temperate belts through winter production zones in subtropical and tropical highlands across the Americas (zones 3–13), with explosions in mild, humid spells and under row cover.
Adults and nymphs are coated with a gray mealy wax; bodies are short and oval with short dark cornicles. Winged forms migrate between summer and winter hosts where the life cycle includes them. Unlike green peach aphid, cabbage aphid often packs tightly into crevices of heading types—field ID is the waxy gray mass and peppery smell when crushed.
How to Deal With It
Organic Control Methods
Insecticidal soap or horticultural oil penetrates wax best with firm water pressure pre-rinse and thorough spray to hearts; repeat on a short interval while new colonies appear. Neem reduces feeding on open-leaf types. Avoid spraying open brassica flowers visited by pollinators; treat inner leaves with directed nozzles where possible.
Parasitic wasps including Diaeretiella rapae lay eggs inside aphids, forming bronze mummies; syrphid larvae and lady beetles clean exposed colonies. Release or conserve lacewings in tunnels. Skip soaps the day beneficial eggs are abundant on leaves.
Use floating row cover on transplants until plants outgrow cover or temperatures demand removal. Remove old brassica residues promptly—volunteer mustards bridge seasons. Blend flowering insectary rows on farm edges to feed parasitoids through summer.
Direct a strong jet into leaf axils on savoy and open kale types every few days for organic market gardens. For small heads, peel and submerge outer leaves in cold salt or soap water as a last-step wash protocol, not a field cure.
Scout the growing point weekly, especially downwind of fall brassica debris. Flag tunnels that ran hot on cabbage aphid last cycle for earlier biocontrol releases. Rotate brassica blocks with non-host families to avoid overlapping generations on adjacent fields.
Let Nature Handle It
Natural Enemies
- Diaeretiella rapae
- Lady Beetles (Coccinellidae)
- Syrphid Fly Larvae (Syrphidae)
- Lacewing larvae (Chrysopidae)
Threat Map