2024 will be a banner year for bug lovers and entomologists alike. Two unique broods of summer cicadas will be emerging at the same time in a very rare event. Cicadas are some of the longest-lived insects in the animal kingdom, sometimes having lifetimes of 17 years. These large insects start their life as an egg laid inside a tree stem or branch. After several weeks the eggs hatch and the emerged nymph falls to the soil where they will spend the next 13-17 years underground. They spend that time sipping the moisture from plant roots as they slowly grow and eventually emerge as adults to reproduce. The precise mechanism by which these insects know it’s their time to emerge is currently unknown.
In Illinois, both brood XIII and brood XIX will emerge simultaneously in 2024. The adults typically begin showing up in late May and persist for about 4 weeks. By July their party will be over and life will return to normal. Somewhat confusingly, brood XIII has a 17-year life cycle while brood XIX has a 13-year lifecycle. Brood XIX will emerge in the southern half of the state and brood XIII will emerge more to the northern half. There will be some overlap in their geographic region where both broods will be active during the same season. This will truly be a once-in-a-lifetime event, having previously occurred in 1803, the same year as the Louisiana Purchase.
Cicadas are mostly harmless animals. They lack the ability to bite or sting humans, although they may be a nuisance pest as they buzz through the air and produce their cacophony of mating calls to the world. We can anticipate the collective song of cicadas to be particularly boisterous during the 2024 season. However, their impact on trees may be more worrisome.
Remember how we talked about the cicada eggs hatching from within splits in tree stems and branches? Adult cicadas use what entomologists call an ovipositor to cut those splits into tree tissues for their egg-laying purposes. On mature trees, this will generally not be very harmful or threatening. If you have a large mature tree on your property, you may notice a higher number of damaged or dead branches later in the year. However, for younger smaller trees the wounding may become significant or even threatening.
If you’ve planted a new tree in the spring and want to keep it protected from any possible cicada harm, mechanical exclusion is the best method for protection. Drape a light net material or mesh tarp over the tree all the way down to the base, and wrap the base fairly tightly. Cicadas are very large insects and won’t be able to penetrate the netting to get to your young tree. The netting may be removed after the cicadas are finished laying eggs, typically in late June or early July.
The use of pesticides isn’t recommended for control and no effective repellents are commercially available. If your tree does suffer damage, Homer Tree Care is prepared to remove any damaged limbs or branches and retain your plant’s health and aesthetic value safely and effectively. We follow the best recommended arboricultural practices and ensure your tree has the best opportunity to recover properly following a damaging event.