There are three species of seventeen-year cicadas [M. septendecim (L.), M. cassini (Fisher) and M. septendecula Alexander and Moore] and also three species of the more southerly ranging thirteen year cicadas (M. tredecim Walsh and Riley, M. tredecassini Alexander and Moore, and M. tredecula Alexander and Moore).
There are 30 broods of periodical cicadas, most separated geographically (Broods I-XVII are 17-year species; XVIII-XXX are 13-year species). Not all are large enough to be horticulturally important. Brood X is the most important numerically and geographically; it last appeared in 2004; it will appear again in 2021. Brood IX is the brood that will appear in 2020 in southwest Virginia. A map of the yearly occurrence of the various broods in Virginia is given in a Virginia Tech factsheet. See an Adobe Presenter presentation (10 minutes) for periodical cicada in Virginia.
II. Hosts: The host range is very broad; almost any tree is attacked except for those that create sufficient gummy exudate to kill nymphs (e.g. pines). Apple is attacked very successfully. Stone fruits may be attacked, especially under heavy population pressure, but are less suitable hosts. Research in Pennsylvania has shown that if the wound is gummed, mortality of the egg mass can result. Gumming increases with the number of attacks per tree. Grapevines are readily attacked, but only young vines are considered to be at much risk.
III. Description: Adults have black bodies with red eyes and red-orange wing veins. Wings are clear and held tentlike over the body. Antennae appear as small bristles protruding from the head. Adult body length is 3/4 - 1-3/10 inch (19-33 mm), depending on species. Males can be identified by the upturned end of the abdomen and the presence of a tymbal just behind the wings. Females have a sharpened ovipositor, used for inserting eggs in wood, that is normally kept retracted in a groove along the underside of the abdomen (the ovipositor drops down for oviposition). Nymphs are seldom seen, since they cling to tree roots as they feed, holding the roots with their grasping front legs.
IV. Biology: Periodical cicada spends most of its life as a nymph, feeding on xylem sap from tree roots at a depth of 6-18 inches. In the final year of development, nymphs crawl from the soil, climbing tree trunks or any other structure. During the night, the nymphal skin splits along the midline, and the adult emerges. Thousands of adults and exuviae (shed skins) may be found with each tree in the orchard. Adults appear in mid-late May (a few individuals may be heard as early as late April in Virginia). They appear around sunset, males slightly preceding females. Males form chorusing centers of great aggregations. The characteristic sound made by males is produced by a membrane called a tymbal, present only in males; this membrane on the side of the first abdominal segment is backed by an air-filled resonating chamber. (note the white structure seen at the front end of the abdomen, just behind the wings in this image). Sound is made by vibrating the tymbal. The structure for hearing, the tympana, are present in both sexes; these membranes are tucked beneath protective plates on the underside of the insect. Singing peaks around 10:00 AM. Adults feed on a wide range of woody plants during the day; such feeding is apparently restricted to the females since the male digestive tract is rudimentary. Oviposition begins about 2 weeks after emergence. Eggs are inserted into twigs in groups of 10-25; the slit into which the eggs are inserted is 1-4 inches (2.5-10 cm) long. Females may lay over 500 eggs. Oviposition peaks in the early afternoon. (See YouTube oviposition clip). Adults are active for about 6 weeks. Eggs hatch 6-10 weeks after oviposition, whereupon nymphs leave the twigs and drop to the soil. Nymphs tunnel to the roots where they establish themselves for feeding. The most important natural enemies of periodical cicadas include parasitic wasps and flies and predatory mites attacking the eggs, and birds attacking the adults. Cicada killer wasps also attack later adults, but these wasps are timed mainly for the later emerging annual cicadas. A fungal disease, Massospora cicadina, infects the adults. However, these natural mortality agents are insufficient to provide control of the massive outbreaks typical of periodical cicada.
V. Injury: The main damage arises from oviposition wounds in twigs. The region distal to the wound dies. This can be very damaging to the structure of the tree, especially in young blocks. There is greater limb breakage during the season on cicada-injured trees. It is worthwhile to delay planting a block if an emergence is expected within one or two years. A second avenue of injury is feeding by the nymphs. A New York study showed that if nymphs were kept from reaching the roots, growth of apple trees was enhanced. Adults may also feed through bark, causing oozing of sap; this is probably of minor importance. In pear, shoot injury from periodical cicada can provide entry to the fire blight pathogen. Affected trees as well as neighboring trees may show flagging.
Most injury in mature vineyards can be tolerated because most oviposition occurs distal to the clusters, and injured shoots will be pruned off later. However, young vines are subject to severe injury, with females using even the trunks as oviposition sites. (See photo by Lucie Morton). Oviposition may occur at multiple sites on one shoot or young trunk; affected areas become weak and will break easily (Eggs in the shoots may be seen on dissection of the injured material). Such young vineyards should be protected. Aluminum foil or some other physical covering of young trunks has been used successfully.
VI. Monitoring: During springs when adult emergence is expected, watch for the appearance of adults in the orchard. No thresholds are currently available. Treat when aggregations begin to appear in the orchard.
Day, E., D. Pfeiffer, C. Bergh and P. Schultz. 2015. Periodical cicada. VCE Fact Sheet, Pub. 444-276.
Hogmire, H. W., T. A. Baugher, V. L. Crim and S. I. Walter. 1990. Effects and control of periodical cicada (Homoptera: Cicadidae) oviposition injury on nonbearing apple trees. J. Econ. Entomol 83: 2401-2404. Pfeiffer, D. G. and J. C. Bergh. 2013. Periodical cicada in 2013. Virginia Tree Fruit Schools, Feb. 2013. (A 10-minute recorded presentation) News report on Brood 5 (2016)