Agriculture and Natural Resources Spring 2008 Newsletter

Cicadas are Here

Spectacular broods of periodical cicadas, designated by Roman numerals, emerge at predictable intervals (13- or 17-years) across the eastern US. Representatives of both occur in the Commonwealth. The emergence of millions of these insects in an area provides a striking visual image and the sounds they produce can be deafening.

Periodical cicadas have black bodies, red eyes, and red-orange wing veins in two pairs of clear wings that are held roof-like over the abdomen. These clumsy fliers often stay in the upper canopy of trees while they are active from late April thru June.  Encounters with periodical cicadas can be unnerving to some but these insects cannot sting and do not harm humans, livestock, and pets.

Mature nymphs begin to emerge when the soil temperature reaches 64o F, usually in late April or early May. It takes about 3 weeks for all of them to come out. Just before leaving the soil, full-grown nymphs dig up to the surface and may build a 6" to 8" tall mud "chimney" similar to those formed by crayfish.

Because egg laying is the real danger from these insects, consider emergence as the signal to begin protecting plants. A week or so after emergence, females are ready to lay eggs. Plants can be protected in three ways: covering, spraying and pruning. Small trees can be covered with a protective netting cheesecloth. Be sure to secure the bottom around the trunk to prevent the insects from crawling up from below. This covering will have to stay on for the next four to six weeks or until egg laying is complete.

Insecticides can be used to reduce damage by cicadas but several applications may be needed. Dursban (chlorpyrifos) and Sevin (carbaryl) are labeled specifically for periodical cicada control. Several synthetic pyrethroid insecticides are labeled for landscape treesand shrubs. Often, these insecticides

have a repellent effect that causes insects to leave treated surfaces shortly after landing on them. The following examples do not list the periodical cicada but are broad spectrum products that are effective against a wide range of insects - Astro (permethrin), Decathlon20 WP or Tempo (cyfluthrin),

DeltaGard T&O (deltamethrin), and Scimitar (lambda cyhalothrin). Several of these are available only to commercial applicators.

Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!

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