Cabbage moth eggs are tiny, yellowish-white, bullet-shaped eggs laid singly on the undersides of brassica leaves. If you’re finding small green caterpillars chewing holes through your cabbage, broccoli, or kale, the eggs were likely there first, and catching them early is the most effective way to prevent damage.
What Cabbage Moth Eggs Look Like
Each egg is roughly the size of a pinhead, pale yellow to cream-colored, and slightly elongated with a ridged surface. They’re laid one at a time rather than in clusters, which makes them easy to overlook. The adult white butterfly (technically the imported cabbageworm moth, Pieris rapae) deposits eggs primarily on the undersides of outer leaves, so you won’t spot them unless you flip the foliage over and look closely.
A single female can lay hundreds of eggs over her lifetime, visiting multiple plants across your garden. The eggs darken slightly as they mature, and larvae typically hatch within about a week depending on temperature. Once hatched, the tiny green caterpillars begin feeding immediately near the egg site on the lower leaf surface, creating small irregular holes that grow larger as the larvae grow.
Where and When to Check
Any plant in the brassica family is a target: cabbage, broccoli, cauliflower, kale, Brussels sprouts, and collards. The white butterflies are active from early spring through fall in most regions, with egg-laying peaking during warm, sunny stretches. You’ll often see the adults fluttering low over your garden before they land to deposit eggs.
Check the undersides of outer leaves every few days during the growing season. Pay extra attention to newer transplants and the largest outer leaves, which are the first landing spots for egg-laying adults. On open-leaf crops like kale, eggs tend to be scattered across the leaf undersides. On heading crops like cabbage, early-stage caterpillars feed between the large veins and midribs of outer leaves first, then work their way into the central head as they mature, where damage becomes much harder to control.
Removing Eggs by Hand
The simplest approach is crushing or wiping eggs off the leaves with your fingers. It’s tedious but effective, especially in smaller gardens. Run your thumb along the underside of each leaf and squash any eggs you find. Do this every two to three days during peak butterfly activity to stay ahead of hatching.
For larger plantings, this becomes labor-intensive quickly. Some gardeners report spending significant time each morning picking off individual caterpillars and eggs from every leaf across multiple rows. If you’re growing more than a handful of plants, combining hand removal with other strategies will save you time.
Physical Barriers: Row Covers
Floating row covers are the most reliable way to prevent eggs from ever reaching your plants. These lightweight fabric sheets made from spun polyester or polypropylene let light, water, and air through while physically blocking butterflies from landing on your crops. They eliminate imported cabbageworms, cabbage loopers, and diamondback moths all at once.
The key detail: covers must go on at planting time, before any adults have had a chance to lay eggs. Bury the edges completely in soil so butterflies can’t sneak underneath. For low-growing crops, you can lay the cover directly over the plants with enough slack for them to grow. Taller brassicas like Brussels sprouts or broccoli do better with PVC hoops bent into arches over the row, giving the plants room without the fabric rubbing against leaves.
If you used row covers last year, rotate your brassicas to a new bed. Pupae from the previous season can overwinter in the soil, and covering the same spot means you’d be trapping emerging moths inside with your new plants.
Biological and Organic Controls
Tiny parasitic wasps in the Trichogramma genus are natural egg predators. These wasps, barely visible to the naked eye, lay their own eggs inside cabbage moth eggs, killing the developing caterpillar before it ever hatches. Trichogramma species have been used against imported cabbageworms in North America since the late 1960s and can be purchased as biological control agents for home gardens. They’re most effective when released early in the season as adult butterflies first appear.
For caterpillars that do hatch, a soil bacterium sold as a spray (Bt, or Bacillus thuringiensis) is one of the most targeted organic options. It kills caterpillars that eat treated leaves but doesn’t affect eggs directly, so timing matters. Apply it when you first notice small larvae or fresh feeding holes.
Neem oil works differently depending on the life stage. On small caterpillars and soft-bodied insects, it clogs their breathing pores and suffocates them. Its active compound also disrupts insect growth by preventing larvae from shedding their skin as they develop, and it deters adults from feeding and laying eggs on treated plants. Insecticidal soap works similarly by coating and suffocating small caterpillars, though both soap and neem are most effective on the earliest, smallest larvae rather than on the eggs themselves.
Recognizing Early Damage
Even with regular scouting, some eggs will escape your notice. The first sign of hatched larvae is small, irregular holes in leaves, usually starting on the underside where the eggs were laid. These holes enlarge as the caterpillars grow. You may also notice dark green frass (caterpillar droppings) scattered on leaves.
On heading crops like cabbage, the real concern is caterpillars boring into the developing head, where they’re protected from sprays and predators. Catching infestations while larvae are still on the outer leaves, ideally within the first week after hatching, gives you the best chance of keeping your harvest intact. A combination of regular leaf inspections, row covers where practical, and a targeted spray for any caterpillars that slip through will keep most brassica plantings clean through the season.