Pest Watch: Whiteflies

If you’re doing your daily inspection of your veggie garden and find an infestation of little white insects on the undersides of leaves, don’t ignore them. These are not aphids, but another insidious sucking insect that can be just as bad, if not worse – whiteflies. Adult whiteflies look a bit like tiny moths, about 1 – 2mm long and triangular in shape, with powdery white wings.

Like aphids and mealybugs, to which they are closely related, whiteflies are soft-bodied, sucking insects that can drastically weaken plants. They tend to congregate on the undersides of leaves, feeding heavily on plant sap from the veins. And like aphids, whiteflies produce honeydew, which in turn attracts ants to the infected plants. Plants that are most often affected by whitefly are citruses, squashes, tomatoes, cucumbers, brinjals, peppers, sweet potatoes, brassicas and okra, as well as ornamentals such as fuchsias and geraniums.

Treatment of Whiteflies

Diligence is key, with regular inspections of your crops, looking underneath leaves and around growing tips. And if an infestation is found, diligence and perseverance are again the answer, with multiple treatments of a pesticide that has been registered for whitefly applied over a period of a few weeks. If you’re not a fan of poison we recommend that you destroy their host plants.

The usual garden heroes (ladybirds, lacewing larvae and other predatory bugs) will take care of a certain number of whitefly adults and larvae, but they won’t be able to eliminate an established scourge. That said, it’s important to interplant the host plants with plants that will attract beneficial insects, such as fennel, parsley and calendula.

Neem oil can be sprayed on infected plants to kill eggs, larvae and adults, but because the adults fly they can be hard to effectively wet. Another method of whitefly control, this one quite peculiar, is to simply vacuum the bugs off the infected plants using a handheld vacuum cleaner, and then dispose of them.