following question was sent to the P&PDL diagnosticians here
at Purdue University:
Question: I have black scalelike insects covering the twigs
of a five year old Tulip tree. During August, there are also scalelike
white/grey fuzzy insects that actively crawl around that I assume
is a mobile stage of these scales. Also the tree is surrounded
by wasps, bees, and other insects. What should I do?
looks like your problem is with an insect called a tulip tree scale.
These insects are immobile as adults and are usually dark in color.
After they hatch from their egg, the crawlers are mobile. These
insects break down cells for sap and other nutrients in the tree
and excrete a clear substance called honeydew. This sugar-like
substance is a favorite meal for ants, bees, wasps, and a fungus
called sooty mold.
Repeated heavy infestations can result in death of branches. The
use of pesticides can be detrimental to beneficial insects, such
as lady beetles and microscopic wasps which are natural enemies
of the scales. However, if infestation is severe, it is possible
to kill the crawlers during mid-August when they are active using
a systematic insecticide. Then use a dormant oil spray next spring.
When using pesticides, read and follow label directions.
--Nathan E. Saxe (June 9, 1998)
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