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In the late
1970's the ash
whitefly invaded Southern California. With no natural predators,
their population exploded. Between the buildings at my school
there were so many whiteflies in the air that it literally looked like
a heavy ash fall from brush fires. (In a different climate I
would have said, "snow flurries".) A number of trees at the
school died as a result of the ash whiteflies. Citrus trees were
especial hard hit. The lower sides of leaves, like this tangelo were
completely covered with larvae and pupae, frequently causing them to
curl and turn yellow.
This photo shows
the size of
adult ash whiteflies, much smaller than the giant
whiteflies . Over years the small birds like the California bush tit
discovered their nutritional value, and species specific parasitic
wasps were imported. Gradually the pest was brought under
"control". This was the worst case I could find when I wanted
pictures for this page.
The sweet,
sticky honeydew exuded
by the larval whiteflies drips onto the upper surface of lower leaves.
The sooty mildew, any of several species of black fungus, find
this a most favorable situation. Dust also sticks to the sticky
mess, and with the thick, black growth, blocks out most of the
light for photosynthesis.
[Taxonomy :
Classification ]
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