Cabbage Whitefly, European Cabbage Whitefly, Tabakwitvlieg (Afr.)
Cabbage Whitefly is a small white insect with white wings, that is a true bug but appears more like a small moth from a distance. Whitefly is an important agricultural pest and a common problem for many commercial crops. They suck the sap from plants, which not only makes plants less able to photosynthesise but makes whitefly possible disease vectors, too. Plants can appear to be covered with black, sooty dust, which develops on top of the honeydew which is excreted by whiteflies. Cabbage whiteflies will only be found on Brassica plants.
Can be a potential vector for spreading disease.
Adults: Whiteflies appear as tiny, white moths or flies which grow to about 1.5 mm. They have four white wings, flying up 'in clouds' when disturbed. Nymphs: Oval and flattened, translucent with a white to green tinge. They look like armoured scale insects. There are four instars. Eggs: Cabbage whitefly eggs are pale green, pear-shaped, flattened and 0.2mm long. The eggs are too small to see with the naked eye. Laid on the underside of leaves.
Whitefly eggs are pale green and laid in circles, beneath the leaves. Wilting leaves followed by early leaf drop. Whiteflies can transmit viral diseases to plants. Feeding causes stunted growth, as well as curling leaves. Honeydew may be found on the upper surfaces of leaves. Honeydew can result in secondary infections in the form of black mould. Ants are attracted to Honeydew and can sometimes make an infestation worse.
Parts of Europe, Asia and Africa, America, Australia and New Zealand
Whitefly infestations tend to be more problematic indoors, for example, in a glasshouse setting. Planting rhubarb in greenhouses is thought to deter whitefly. Whitefly eggs can be found underneath the leaves of plants, so these areas should be inspected regularly. Remove Whitefly eggs with a cloth and soapy water or rubbing alcohol. Any spacing between plants should be kept clear of weeds and debris. The use of netting can sometimes improve protection for garden plants. For lighter infestations, plants can be gently hosed down to remove whitefly and eggs. Ant traps placed near affected plants will aid controlling any secondary infestations. Whiteflies are drawn to the colour yellow. You can use yellow cards or sticky traps to attract whitefly and monitor the infestation level. Insecticidal soaps and neem oil can give some control over whitefly, and it's less harmful to the environment when compared with pesticides. Bottle labels should be read carefully. Oils can react badly with high temperatures and burn the surfaces of plants. Beneficial garden creatures such as beetles, wasps, lacewings and spiders will eat whiteflies. These can be attracted into the garden using a few simple tricks, such as incorporating insect hotels or by letting parts of the garden grow a little wild. Try catching ladybugs and place them on infested plants.
There are pesticides available for home gardeners. Please note, whiteflies quickly develop tolerance to the toxins found in sprays. If you are planning to eat your harvest, make sure the plant is listed on the bottle label and follow instructions.