Whitefly
Symptoms
Tiny white creatures cluster under the leaves, they fly up into
a cloud if the leaves are disturbed. Both the adult and larval whitefly
excrete a honey-dew which encourages black sooty mould. Whitefly
is most commonly found on houseplants and in greenhouses.
Harm
Like most sap-sucking insects the whitefly will weaken the plant
and make it suseptable to further attacks of pests and disease.
Treatment
Organic - tap the leaves and as a cloud of flies up, suck
them up with a vacuum cleaner. There are also organic soap sprays
which are affective such as Nature's Answers. White flies are also
attracted to yellow paper, so hang strips of sticky yellow card
which the flies fly at and stick to.
Chemical - there are lots of sprays you can use. As the whitefly
move so rapidly a systemic spray is probably a good idea. A systemic
spray enters the plants sap killing the insect when it feeds. (A
contact insectiside only kills when it comes into contact/touches
the insect).
Biological - the biological control for whitefly is the parasitic
wasp Encarsia formosa. These minute wasps parasitise the whitefly
pupae. Each wasp can parasitise up to 150 whitefly. The wasps are
harmless to all other insects and animals.
ps feeding within hours and will die a few days later.
Source:
Crocus
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