Last week we had the first reports of Brood II cicadas emerging from the earth in Stokes County, NC, and on May 7 and 10 cicadas were reported in Spotsylvania, VA, and California, MD, respectively. Sightings should become more common this week in the suburbs of Maryland and northern Virginia and in the piedmont communities lining the eastern face of the Blue Ridge. Like a huge tsunami, this exodus will continue to roll up the eastern seaboard from North Carolina to the Hudson Valley in New York and eastward to central Connecticut as the warmth of spring extends its northern reach. In the path of this biological deluge are major metropolitan areas and their suburbs including Hartford, New Haven, New York City, and Philadelphia. While the vanguard of cicadas is on the move along the east coast, the chorusing of thousands of cicadas in the treetops of the southern suburbs of Washington, DC, is still a week or two away. The last brood of cicadas to emerge in St. Mary’s County, Brood XIX, cranked up the big boy band in the treetops in the last two weeks of May 2011 (see St. Mary’s Survivors, June 6, 2011).
One of the cicada-related questions that popped up this week was the potential harm these boisterous bugs might inflict on the human population. Remember, cicadas will not bite you, your children, or your pets. In fact many creatures, including your dogs and some humans, relish the opportunity to dine on cicada snacks. Cicadas will suck small amounts of sap from plants, but this feeding is, apparently, inconsequential. The real concern for us is the injury that results when females lay eggs (oviposit) in the small branches of woody plants. The following information is excerpted from a publication by Robert Ahern, Steve Frank, and the Bug Guy: “Trees commonly damaged by cicadas are fruit trees, oak, maple, dogwood, and redbud, but over 200 species are susceptible. Cicadas will not damage most evergreen trees. Periodical cicadas cause damage to trees when they gouge slits in thin branches to lay eggs. Cicadas will lay eggs in branches 1/4 to 3/8 inch in diameter. Twigs of this size that have slits gouged into them by female cicadas may die. This damage, called flagging, will not kill large, established trees. However, small trees with many small branches could suffer considerable damage or die from extensive cicada oviposition. Trees less than six feet tall are at the most risk of incurring severe damage from cicadas. The most effective way to protect small trees from cicada damage is with mesh netting. The netting must have holes 3/8" in diameter or smaller to prevent entry by cicadas. To be effective, protective netting should be installed prior to cicada emergence in mid-May and remain on the trees until cicadas are gone at the end of June.” So, now is a fine time to purchase netting and protect your saplings if cicadas will be visiting your neighborhood this spring.
A female pumps egg into a branch through an appendage called an ovipositor.
This episode was inspired by Adrian Higgins, Gaye Williams, and John Zyla, Maryland’s local cicada expert. The articles by Robert Ahern, Steve Frank, and Michael Raupp “Comparison of exclusion and imidacloprid for reduction of oviposition damage to young trees by periodical cicadas (Hemiptera: Cicadidae)” and “Periodical cicada, protecting susceptible trees with mesh netting” were used as resources for this episode.
To view the fact sheet describing how to protect trees from cicadas, or previous stories regarding Brood II, please click on the following links: