Q. I have a serious infestation of hard shelled black
insects on my oleanders. I have a tree-like hedge of oleanders on both sides of
my home. One of the oleanders is heavily infested but the problem is spreading
rapidly to all the others.
When I discovered the problem this weekend the oleander
was black with thick black shelled insects about the size of an apple seed with
sticky honeydew dripping down the trunk and stems. My neighbor thought they were
black aphids so I power sprayed the oleanders with water and used a soapy water
rinse. Unfortunately, the bugs seem to be adhered and need to be picked off.
They are not on the leaves but are on the stems and trunks and climb higher
than I can reach. I am attaching photos and would appreciate any advice you can
give me. Will the 100o+ weather kill them? I removed the most
heavily infested branches but that barely made a dent in the insect population
so I wonder if I have to remove the whole oleander tree.
A. This is one of the many scale insects. Scale insects are
not terribly common in southern Nevada. They are difficult to control because
the insect is living under a protective “shell” it created.
the insect does not move around once it creates its “shell” they don’t attract
attention. Frequently they come to our attention because of the sticky sap they
excrete is shiny and attracts ants.
the question becomes how can I control ants, not realizing the ants are there
because of other insects like scale and aphids. The ants can move the scale insects around so it is best to control them as well.
If you don’t have very many of them you can treat each scale with alcohol and a cotton swab. But usually there are too many.
usual recommendations for controlling scale insects is to either spray a
horticultural oil on top of them in early spring to suffocate them or use a conventional
insecticidal spray. a conventional insecticide when the insect is no longer
protected by its hard outer covering, the scale itself. Never spray an oil when a plant is in bloom. Usually two winter or early spring applications are called for.
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| One of the many horticultural oils for suffocating insects. Particularly good on soft-bodied insects like aphids, mites and the like but they will also kill beneficial insects so use it where and when it is needed and not indiscriminately. |
These insects are not hard to kill when they are not under those shells. The females release young scale insects without the scale (called crawlers) around May. It is at this time the insects are most vulnerable. It is also the time when it starts getting hot and the spraying oils in the heat is not recommended. I have done it very early in the morning with no problems to the trees but you must do it early in the morning.
small area of the plant first and wait 48 hours to see if the plant reacts
negatively to it. If it doesn’t, go ahead and spray in the summer as well but
do it in the cool morning hours right after sunrise.
When you say spray with oil what do you mean??
Dormant or Horticultural oil, not Neem or any of the other oils.