How do you get rid of bugs on cauliflower?

Question: I can’t tell which pests are eating the cauliflower leaves. How do you get rid of bugs on cauliflower? -Richard W.

Answer: Common signs of an insect infestation are holes in leaves, tracks on foliage, missing vegetation, and stunted growth. Common cauliflower pests include aphids, flea beetles, slugs, snails, leafhoppers, and several types of insect larvae. Insecticidal soap or oil is often used in controlling bugs on cauliflower plants. Smaller insects, such as aphids, can be knocked off of the plant with blasts of water from the garden hose. Slugs and snails have to be picked off of the plant by hand or otherwise dealt with by spreading diatomaceous earth, which is also the recommended method for controlling flea beetle infestations.

Sucking insects, including aphids and harlequin bugs, can cause damage to healthy cauliflower plants. Aphids can damage stems, leaves, and flowers, mainly sucking sap from leaves and stems. They attack the succulent flower and cover it in a sticky honeydew secretion which stunts the growth of all parts of the plant. Harlequin bugs feed on plant sap and cause foliar death. Insecticidal soap is often used against both of these common cauliflower pests.

The larvae of many different insects and moths are known to attack the cauliflower plants, namely cabbage webworms, cabbage loopers, cross-striped cabbage worms and imported cabbage worms. Webworms are small, ⅜ inch green striped larvae which spin webs, and cabbage loopers are light green with yellow stripes which get their name from the way they loop when they walk. Loopers are an invasive larvae, which tunnel through the head of the cauliflower, causing severe crop damage if left untreated.

Cross-striped cabbage worms are small grey larvae with horizontal black stripes and a light green yellow mottled underbelly. Imported cabbage worms are green with a narrow orange stripe down the back. The insects and moths that commonly attack cauliflower plants are treated by releasing parasitic wasps or by spreading Bacillus Thuringiensis (BT).

Other common bugs that are found in cauliflower plants include slugs, snails, flea beetles, blister beetles, and yellow margined leaf beetles. Slugs, snails and flea beetles are all commonly treated by spreading diatomaceous earth to deter them from coming near your crops.  Use pyrethrum and cultivate in spring to kill blister beetle larvae, while yellow margined leaf beetles must be picked off by hand and can be somewhat deterred by DE.

Since cauliflower is cultivated for eating, you should use non-toxic safe methods for treating bugs to preserve the crop while making sure it is still safe for consumption. Besides diatomaceous earth, horticultural oils and soaps, hand picking, and the natural bacteria Bacillus thuringiensis, are all excellent options for treating common pests of the cauliflower plant. You may also choose to purchase natural enemies in the form of beneficial nematodes and wasps to release in the garden to fight your pest population.