Cabbage Worm Location
The Imported Cabbage Worm came to this country from Europe, via Quebec, arriving in Massachusetts about 1869, and quickly spread to all parts of the United States.
It attacks all members of the cabbage or mustard family (this includes cauliflower) and also feeds on nasturtium, sweet alyssum, mignonette and lettuce.
Cabbage Worm Appearance and Habits
The insect winters in the pupa stage, a gray, green or tan angular chrysalid hanging downwards from some object near the cabbage patch. In early spring, the pupa hatches into a white butterfly with three or four black spots on each wing, a wingspan of 1 1/2″ to 2″. They lay yellow, bullet-shaped eggs singly on the undersides of leaves. In about a week, velvet-smooth green caterpillars, with alternating light and dark longitudinal stripes, hatch and start feeding, depositing pellets of dark green excrement as they eat huge, ragged holes in the leaves. They feed for 2 to 3 weeks, then pupate, there being three to six generations in a season.
How to Control Cabbage Worms
Plant tomatoes, onions, garlic, and sage around cabbage to deter the worm.
Cover plants with a lightweight nylon net to keep the butterflies from laying eggs.
Till the soil several times between plantings to destroy eggs and pupa.
Hand-remove larvae. Destroy old stalks as soon as the crop is harvested, and make sure to destroy weeds like Wild Mustard, Pepper Grass, Shepard’s Purse, on which the first-generation worms develop.
A number of natural enemies reduce the caterpillar population, among them common yellow jackets and braconid wasps. Braconid wasps are attracted by strawberries.
The cabbage worm may drown during heavy rains.
Other methods include spooning spoiled milk into the cabbage head, or spraying with a mixture of salt, flour, and water, which will make the caterpillars bloat and die.
Pictures of a Cabbage Worm
Cabbage Worm (Life Cycle, page 52): A. adult butterfly; B. full-grown worm (larva); C. egg, enlarged 10 times; D. chrysalid; E. typical damage by worms, adults laying eggs