The periodical cicada, a member of the magicicada genus of the species, emerges every 17 years like clockwork in our region. If you are a long time Washington, D.C. resident you remember just how many covered our urban streets and sidewalks in 2004. They seemingly popped out everywhere. I will spare you lots of visuals in this blog, you get the idea!
The periodical cicada season will being this spring when soil temperatures rise to 64 degrees. In our region this is early May. Their active mating season lasts for 3-4 weeks before subsiding.
The sad reality is that during their active life cycle, these not so little insects are capable of causing substantial damage to newly planted woody trees and shrubs. The damage occurs primarily when female cicadas lay their eggs on these plants. Fortunately, they avoid mature woody vegetation, perennial plants, annual flowers and evergreen shrubs,
Ideally, mass plantings of woody shrubs and trees should be avoided during March-May of this year and fall planting is your best option. You can protect vulnerable trees and shrubs from cicadas by covering them with an agricultural netting of ¼-inch mesh or less. Mesh sizes larger than ¼ inch will afford little protection because cicadas can penetrate this.
Foil and barrier tape, available at most garden centers, can also be applied to the base of trees and shrubs. These sticky bands catch cicadas trying to move up the plants to lay eggs.
Spraying the branches regularly and thoroughly with a garden hose will knock these critters off the new plants. This process requires more diligence but will minimize the damage they can cause.
Pesticides can be applied to provide temporary protection from the cicadas, but their use is not recommended. The longer term environmental impacts outweigh the benefits and treating the insects directly may also sicken animals that ingest them.
As surely as these oval-shaped winged insects will emerge they will again go dormant. They are not harmful to humans or to pets. Cicadas do have some long term benefit by helping to aerate the soil, and when they decompose they add an important source of nitrogen which can be beneficial to growing trees.
In my humble opinion, and I think most would agree, these are not good enough reasons to have them around. Fortunately, after this season, we won't have to deal with these large populations again until the spring of 2038.
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