When people plant a garden, they will often place the broccoli and the cauliflower together. This is beneficial for spacing purposes, but it is also harmful. The biggest reason why that is harmful is because broccoli and cauliflower belong to the same family, therefore they share the same pest problems. The closer the plants, the easier it is for the pest to travel. Cabbage loopers, imported cabbage worms and diamondback moths are the three biggest threats to cauliflower and broccoli.
A diamondback moth is easy to identify once it has reached the adult stage because it has diamond patterns on its wings. The gray moth will lay eggs on the underside of the broccoli leaf and sometimes on the cabbage plant. The eggs hatch within one week and are light-green to yellowish in color. Each end of the caterpillar is pointed. The caterpillars eat through the leaves, marking the entire greenery on the plant with small holes and damaging the flowers. The diamondback moth will produce two or three generations of pests each growing season, until the crops are picked or a hard frost hits.
Imported Cabbage Worms
An imported cabbage worm begins as a white egg on the underside of the leaf of a broccoli, cauliflower or cabbage plant. In late June, the eggs hatch and green caterpillars crawl over the leaves and heads of the plant, eating anything in its way. The green caterpillar will change into a yellow worm with a stripe down its back in one to two weeks. The last stage is when it turns into a cocoon on the plants in the garden and emerges as a silver to white moth. The moth lays eggs and the cycle begins again, until mid to late July.
A cabbage looper egg is very small and will hatch caterpillars in three to four days. The caterpillars are light green to yellowish brown in color and have different shades of stripes along the body. The caterpillars will grow in stages and end up being close to 2 inches long. Once they are full size, they will spin a cocoon, or pupa, that is 3/4 to 1 inch long and brown in color. Within two weeks, a moth will emerge and lay eggs on the leaves again. Up to four generations of loopers can be produced in one ideal growing season.