Cicadas

Overview 

Cicadas are in the order Hemiptera which is comprised of insects that use piercing-sucking mouthparts to feed. There are two groups of cicadas: annual and periodical cicadas. Annual cicadas (Neotibicen spp.), also called dog-day cicadas, emerge every year and periodical cicadas (Magicicada spp.) emerge every 13 or 17 years depending on the brood.  

2024 Periodical Brood XIX (13-year Great Southern Brood 19) and Periodical Brood XIII (17-year Northern Illinois Brood 13) 

For the first time since 1803, when Thomas Jefferson was president, Brood XIX and XIII occurred simultaneously (the next time these two Broods overlap will be in the year 2245). They did not emerge in the same area: Brood XIX occurred in most of Missouri while Brood XIII occurred primarily in Northern Illinois. Brood XIX was comprised of four different species of cicadas (M. neotredecim, M. tredecim, M. tredecassini, M. tredecula) and is found in 14 states.  

Symptoms & Diagnosis 

The most prominent signs of cicadas are the loud mating call of the males and the presence of exoskeletal sheds. Tree flagging may be noticeable (the very tips of branches are dead) and upon inspection damage from the female's ovipositor may be seen. Tree flagging acts like natural pruning and does not harm mature trees, it actually helps them. 

Annual Cicadas appear in late summer and are brown-green with dark-colored eyes. They are larger than the periodical cicadas, growing up to 2 inches long. 

Periodical Cicadas appear in late spring and are black with orange markings and red eyes. The periodical cicadas are typically smaller than annual cicadas, reaching 1.5 inches in length. Periodical cicada mating calls harmonize and can be as loud as a lawn mower or a jet taking off. 

Life Cycle 

Annual cicadas emerge in late July through September, and Periodical cicadas emerge within a few nights anywhere from late April through May (once soil temperatures 8 inches under reach 64^oF). After cicadas emerge from the ground, they spend only a few weeks above the soil. Cicadas emerge and crawl up almost any vertical object around (trees, fenceposts, even house siding) where they molt into their adult form. The molting process takes a few hours including the time it takes for the new exoskeleton to harden and wings to form. The males will use loud mating calls to attract females to reproduce. Females will lay eggs into twigs using an ovipositor; each ovipositor slit can contain 10-25 eggs and each female can lay up to 400 to 600 eggs in her lifetime. After reproduction is complete, the adults die. In 6-10 weeks the eggs hatch, the twig falls to the ground, and the nymphs burrow into the soil down 6-18 inches below the soil line. The nymphs live underground for several years using their mouthparts to suck the plant sap out of the roots (starting with grass roots and moving up to tree roots). Periodical cicadas stay underground for either 13 or 17 years, depending on the Brood. Annual cicadas live underground for anywhere from two to five years with overlap happening every year. Periodical cicadas will start approaching the surface of the soil a month or so out from total emergence often forming mud-tunnels that expose them to the surface, this is common with overly wet soils.  

Human & Ecosystem Connections 

Cicadas are not harmful to humans or pets but can be a nuisance as they are clumsy fliers. If held, cicadas may attempt to use its mouthpart to poke skin, but cannot chew or bite. Cicadas cannot jump, only crawl and fly. Cicadas can be eaten and provide a great source of protein and vitamins, but they are best eaten before their exoskeleton hardens (they will be pale in color). Most pesticides are not effective on cicadas and will do more harm than good. The timeframe in which cicadas are present is short enough that control is not needed. 

Benefits 

Cicadas are a major food source for birds and other fauna when available. Periodical cicadas emerge in such large numbers that they cannot be all consumed before new eggs are laid, so it is a wonderful buffet for many insect-eating birds. This overabundance can cause a rise in caterpillar numbers since birds prefer the cicadas over their typical caterpillars. On mature trees, the process of egg laying acts as a natural pruner since the tip of the branch where the eggs are laid falls off when the eggs hatch. Nymphs burrow into the soil and can help aerate. Any cicadas that are not eaten provide nutrients to the soil as they decompose. Cicadas are the only food source for cicada killer wasps larvae (Sphecius speciosus). 

Damage to Trees 

Since periodical cicadas emerge in spring, caution should be used when planting young trees in spring or the fall before the emergence. Keep trees healthy and watered to help them better recover from any cicada damage. Since female cicadas can cause tip die-back, and the nymphs feed on roots, young trees can be killed if overwhelmed by cicadas. If you have recently planted trees (less than 3 years) or the caliper of the tree is less than 2 inches, you may want to cover the tree with loose, fine mesh netting, ensuring the netting is secured to the tree trunk so that cicadas cannot enter the tree canopy. Be sure to remove the netting as soon as the cicadas have died off. Annual cicadas emerge late enough in the growing season where any damage done is very minimal.