Whitefly
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Adults and larvae of the Greenhouse Whitefly
Adults and larvae of the Ash Whitefly
A number of whitefly species will attack a range of vegetable and ornamental plants.
Whitefly tend to develop in low numbers throughout spring, with an apparent population explosion occurring in early to mid summer.
Two of the more common whitefly problems reported by home gardeners are the Greenhouse Whitefly and Ash Whitefly.
Greenhouse whitefly are the more common of the whiteflies generally found around the garden.
Ash whitefly is more commonly found in South Australia and New South Wales.
Damage
Whitefly cause damage in several ways. Most obvious is the high level of sooty mould that results on foliage around the Whitefly. Whitefly excrete a sugary solution called honeydew, on which black mould develops, leading to unsightly damage.
Whitefly can also act as carriers of a range of plant diseases, especially viruses.
Monitoring
Check fresh growth for the presence of whitefly, especially the underside of leaves for the presence of larvae. As the accompanying photos indicate, it is the larvae that are more easily differentiated.
Control Options
Sprays such as white oil need to target whitefly larvae as opposed to adults, and need to completely smother the pests for control to occur.
Toxic chemicals will have more control, but re-infestation can easily occur again, as the pesticide will also kill all of the good bugs, and a cycle of infestation and chemical applications will start!
Good bugs may offer a better alternative.
Adult Lacewing
Lacewings – Whitefly Predator
Lacewings consume a wide range of common pests, and they quite effective against whitefly. The Green Lacewing is a native to Australia and is found throughout all states.
Lacewings work best if released before large numbers of whitefly build up.
Encarsia wasp on larvae
Encarsia – Whitefly Parasite
Encarsia is a tiny parasitic wasp that attacks Greenhouse whitefly in particular. This is an effective control option for this pest, although it is not recommended for the control of Ash Whitefly.
The advantage of using these predators is they do the work of finding and killing the whitefly for you. The need to apply a spray to every surface of every plant in the garden is time consuming.
Using lacewings and Encarsia to do this for you gives you more time to actually enjoy your garden!
For further information on this or other pests and how to control them, email questions@bugcentral.com.au
