QUESTION: Do Brussels sprouts have worms in them? Where will I find them on the plant? -Larry R.
ANSWER: The small green caterpillars that commonly feast on Brussel sprouts are either army worms or cabbage loopers. Both insects can cause a lot of damage to the leaves and stems of your Brussels sprout plants if left untreated. Aside from the holes they leave behind in the plant’s leaves as evidence of their presence on your plants, they are hard to catch. This is because the insects hide under the leaves during the day and feed late at night when you are unlikely in the garden.
Army worms are dark green and feed in groups. The larvae eat the leaves, stems, and roots of many different plants. The larvae are the result of adult grey moths, which lay their eggs in mass on the leaves or stem of Brussels sprout plants. Newly hatched larvae feed on crown leaves by forming webless perforations, while older larvae cut the stems of the plant and feed on leaves, leaving behind irregular holes in the foliage.
Cabbage loopers are light green with yellow stripes that run down the back of the worm. The cabbage looper caterpillars loop as they walk, which is where they get their names. They are a result of adult brown-colored moths, which lay their eggs on plant debris. The hatched larvae typically only feed on older leaves making irregular holes nearly identical to those left by army worms.
With a little preventative measures, you can help prevent these worms. Keep an eye on your plants. You’ll want to check under the leaves regularly. Look for egg masses, stem and leaf damage, and worms. Pick them off by hand and crush them or put them in soap water to kill them. Spray homemade insecticide soap solution to repel or kill the insects. Prepare the solution by mixing one tablespoon of cooking oil with two tablespoons of baking soda and a few drops of ivory soap into one quart of water. Alternatively, you can use biocontrol agents like Bacillus thuringiensis (BT) or spinosad, or place commercial traps to catch the adults. Keeping your garden free from weeds and debris will help to prevent worms in the garden.