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Agriculture & Natural Resources Updates for Fannin & Gilmer Counties

Did you know there are two types of cicadas commonly found in the Eastern United States? The most familiar is the annual cicada, also known as the “dog day cicada”, which we see every summer. The periodical cicada, as you’ve likely heard in various news outlets, is the other type and it is getting a lot of buzz right now.

The excitement over this insect largely has do to with its extraordinarily long life cycle, as this type of cicada only emerges every 17-years! Emergence is based on the timing of different broods. For example, “Brood X” will emerge across the Eastern U.S. this spring and is comprised of three different periodical cicada species.

Fortunately, one does not have to be an entomologist to tell the difference between an annual and periodical cicada. Live periodical cicadas have bright red eyes, a black body, and orange wings. In contrast, the more familiar annual cicadas that we see every summer have black eyes and green wings.

Another distinguishing factor is a difference in emergence intervals. Periodical cicadas emerge in spring, generally in the months of April and May, whereas annual cicadas begin their emergence later into the summer from June to October. Just like annual cicadas, periodical cicada nymphs emerge from finger-sized holes in the ground and crawl up tree trunks or fence posts to shed their skins. I imagine our 4-H’er’s will be just as good at finding the cast skins of periodical cicadas as they are at finding those of annual cicadas!

Adult periodical cicada, Fannin County, GA 2021

The southernmost range of this brood includes Northeast Georgia, so Gilmer and Fannin counties may see some this spring. While the exact timing of Brood X is not certain, we know that these insects respond to phenological cues to guide their life cycle. Once the 8-inch soil temperature reaches a sustained temperature of at least 64 degrees Fahrenheit, cicadas will begin to emerge. So, local weather conditions certainly come into play here.

For those who may be concerned over whether these insects pose a risk to health and safety, I assure you there is no need to despair. Adult periodical cicadas cannot bite or sting, so they pose no risk to humans and animals. Though, I don’t recommend allowing your pet to eat an excessive amount of them, as it may lead to stomach upset as one would expect from overindulging in any type of food.




Annual “dog-day” cicada, David Cappaert, Bugwood.org

Ultimately, these insects are a huge benefit to local wildlife. Some of the beneficiaries of these tasty snacks include fish, mammals, birds, reptiles, amphibians, and even other insects! For example, local turkey populations will thrive this year since flocks will be so well fed after feeding on periodical cicadas.

While periodical cicada nymphs live underground for 17 years, feeding on sap from tree roots, they only live aboveground as adults for a few weeks. During this time, they mate and lay their eggs in tree branches. Eggs will hatch and the newly-hatched nymphs fall to the ground and burrow into the soil where they will attach their mouthparts to underground roots and feed on sap for the next 17 years. Because they are so small, their feeding does no damage to the tree.

However, the branch tips where the eggs were laid may dry up and break off the end of the limb. While these brown areas, called “flagging,” may appear unattractive for a week or two, they are actually beneficial to the trees. During the next ice storm, limbs will not break off trees because the cicadas have already pruned them! That’s why periodical cicadas are known as “Nature’s Pruning Service.”

Adult cicadas do not feed on crops, so there is no risk to commercial plantings or home gardens. Newly-planted tree seedlings may be damaged if many female cicadas lay their eggs in their branches, so don’t plant young trees until after June 1st this year.

Humans only get to experience periodical cicada emergence a few times in their lifetime and it can be quite the spectacle to behold. If you’re interested in this unique natural phenomenon, download the Cicada Safari app at https://www.cicadasafari.org/ and use it to report where you’re finding cicadas. 

All things considered, periodical cicadas are not pests. They are unique insects that benefit many different members of our wildlife community and should be enjoyed and shared with youngsters so they can appreciate nature at its noisiest!

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