Cicadas are those
large (up to 1˝ inches long), dark greenish colored
insects that serenade us to sleep during the summer.
There are two categories of cicadas in the
United States
One
is the typical cicada that has a one year life cycle
and a few of them show up each summer.
The other type is
called the periodical cicada. These show up on
either a 13 or 17 year cycle and they arrive by the
millions. Entomologists have been tracking the
periodicals for a century and more and can predict
when and where they will emerge. Sometimes they are
mistakenly called locust which are actually just a
large sized grasshopper. Cicada are a different
beast entirely.
The yearly cicadas
emerge in very small numbers and cause little, if
any, damage to our plants. They do not warrant and
treatment.
Periodical
cicadas with their massive numbers are a different
story. They do not eat plants but they cut into
twigs in order to lay their eggs. A couple of yearly
cicadas will cause a couple of twigs to die.
However, several thousand periodical cicadas in a
tree will cause noticeable damage. You will get
large numbers of twigs and their attached leaves
turning brown.
Keep your trees as healthy as possible.
You may be able to
control many of the periodical adults by spraying them
with an insecticide labeled for cicadas. Since they do
not all emerge from the soil at once, you may have to
make a second application 6 or 7 days later. Keep an eye
on the local news and they usually have stories about
periodical cicada emergence. If you have smaller trees,
they may be covered with mosquito netting to prevent
damage. Avoid planting new trees during springs when a
13 or 17 year cicada emergence is predicted.
The small number of
yearly cicadas that emerge are not worth treating.
Note: We
have provided some general information and
observations on this topic aimed at the home
gardener. Before you take
any serious action in your landscape, check
with your state's land grant university's
Cooperative
Extension
Service for the most current,
appropriate, localized recommendations.