White flies are sucking insects. You will notice white colored pinpoints on the upper surface of the leaves when they are congregating and sucking the plant juices from underneath. When excessive, they can cause the leaf to dry up and die.
They can be infectious vectors for plant diseases (to plants, you understand).
Like all sucking insects, their feeding attracts ants to the sticky "honeydew".
I don't believe any of this can cause problems for your other uses in the area.
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