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 Brood
XIII (13) and Brood XIX (19) will both be emerging at about the same
time in Illinois, and for four to six weeks afterward our days and
nights will be filled with the weird sound of the bug as the males
release their mating call, bringing the ladies to the party.
The first brood (19) is said to emerge from the ground every 13
years. The second brood (13) is a 17-year emergence. It is rare for
two such significant broods to emerge in one year, which is why we
are going to see unusually large populations of the bug in Illinois
this year, but only in certain places.
According to experts, brood 13 will be prominent in the northern
part of the state while brood 19 will be more prevalent in the
south. However, there is one little caveat to that statement. There
is an overlap of north and south, and guess where it falls? Right in
the heart of Central Illinois. It is predicted that in our part of
the state the double dose of cicadas may occupy an area from
Sangamon to Peoria and McLean counties, putting Logan County right
in the middle of the noisy mess.
Throughout history there is a bit of confusion about
what a cicada is. Some recall the locust of biblical times. There
was also an invasion of locust in the United States in the late
1800s. In both cases the ugly bugs wreaked havoc on agricultural
crops and created terrible hardships everywhere they invaded.
Cicadas and locusts however are not the same thing, thankfully.
Cicadas are not harmful to agriculture thus they will not destroy
food crops. However, they can be harmful to young trees.
Locusts are reported to be swarming insects, which cicadas are not,
therefore one should not fear running into large swarms like we
often see in those tiny little buffalo gnats.
What one can expect is to find dozens if not hundreds of the crusty
outer skin shells lying around the bases of trees and other woody
plants.
So where do these bug bugs come from, and where have they been for
the last 13 or 17 years?
View this video by the Weather Network
https://www.youtube.com/watch?v=2NKHNG0i_W4
The life cycle of the cicada is someone lobsided. It spends its
first 13 or 17 years submerged underground. While there in its
larval stage, it feeds on the nutrients found in the roots of trees
and shrubs, growing until it reaches that pubescent stage that we
see above ground. When the time is right, large bugs emerge from the
soil, typically this is a nighttime event, so we seldom see the bugs
coming up out of the ground. We just know that one day we don’t have
any and the next day we have hundreds.
Once these “teenagers” arrive above ground, they seek out woody
plants, primarily mature trees where they attach themselves to the
surface. This provides the bug with an anchor as the young adult
breaks out of the crusty shell of the teenager. The young adult
emerges from the crusty shell as a white almost translucent insect
with translucent wings. While the wings remain relatively clear, the
body of the insect will darken to become what we often see
habituating trees and feeding on their leaves.
At this point it is mating time for the bugs. While
they are munching on leaves, this is not necessarily harmful to
trees. They are consuming nutrients, maturing, and beginning their
next cycle. The male bug calls to the female utilizing a vibration
in the belly side of the body that creates that crazy loud sound
that we will hear throughout their mating cycle. The ladies are
drawn to that sound and thus the mating process begins.
When the time is right, the female will then lay her eggs, and here
comes the point in time when we should be concerned for the health
of our trees and shrubs.
The females will choose their egg location, seeking out younger
trees and shrubs with small twigs. This will be living green twigs
no larger than an old school number two yellow pencil. The insect
pierces the skin or bark of the twig and implants its eggs. This
piercing causes damage to the twig. With heavy infestations, a twig
will be pierced multiple times by a variety of females during the
season. Those punctures, commonly called “flagging” will eventually
cause the death of the twig. On small young trees, this can mean the
loss of the tree altogether. The bugs are
not terribly picky about the trees they select. They will not choose
an evergreen tree or shrub, but other than that, any tree in your
lawn is capable of being an attractive incubator for the next
generation of cicadas.
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So, the question becomes, how do we save those young
trees and shrubs from these insects. Once the damage is done, the
answer is, you don’t. So the key to successfully protecting your
trees is to be prepared ahead of time.
Insecticides have proven to be ineffective with cicadas, so don’t
waste money and time on bug sprays. The best method of prevention is
going to be tree netting. Tree netting can be found at garden
centers where trees are sold or can be purchased online. Cover the
trees early this spring and don’t uncover them until the cicadas
have completed their life cycle, about six weeks after they come on
the scene.
The netting should be put on to cover the tree and touch the ground
all around the tree to help avoid the invasion.
If you are thinking about planting new trees and shrubs this year,
unless they are evergreens, you might consider putting it off for
another year.
And, to protect yourself, you might want to consider buying a set of
earplugs or noise cancelling headphones. At the peak of their mating
season the sound let off by the male cicada will reach 90 decibel’s,
about the same as a push lawnmower. When it first starts it is a bit
of a romantic sound, reminding us of the fact that we are enjoying
the warm nights of spring and summer, but after all those weeks, the
sound may become a little irritating, so be prepared with something
that will muffle that sound other than covering your head with a
pillow at night.
So we know that these bugs can cause inconvenience and some tree
damage, but what do they do that is beneficial.
First, they are good food for other critters. The
crusty shells are nutritious for birds and small wildlife such as
squirrels, so they will eat the surplus happily. They are also a
source of nitrogen for the trees as the shells decay, so you can
leave the shells on the ground around the trees and allow them to
self-compost around the base of those trees. The act of boring
underground to find their nesting spot offers aeration for lawns and
helps breakup hard soils.
And finally, if you are brave, they are edible by humans. Not many
people we know are anxious for a nice fried cicada or a cicada stew
this summer, but the fact is they are known to be a delicacy and
have even been featured on Bizarre Foods with Andrew Zimmerman.
So, watch out for the cicadas this year, and be prepared for those
noisy nights because indeed, indeed they will come!
[Nila Smith]
Sources
The cicadas are coming! Periodical cicadas in
Illinois in 2024 | Illinois Extension | UIUC
periodical_cicadas_2024_brood_fact_sheet.pdf (illinois.edu)
Do Cicadas Damage Trees - Learn About Tree Damage
From Cicada Insects | Gardening Know How
How to protect your smaller trees from cicadas (wcpo.com)
Cicada Brood XIII, Brood XIX damage to trees and
shrubs: How to manage (usatoday.com)
What is the purpose of cicadas? - Cicada Mania
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