Periodical cicadas spend most of their lengthy lives underground as nymphs, relying entirely on trees for survival. This relationship is two-fold: nymphs feed on root fluids during their subterranean stage, and females use tree branches for reproduction during their brief emergence as adults. The choices cicadas make regarding host trees determine the long-term habitat for their offspring, making the selection process highly specific.
Favorite Hosts for Feeding and Ovipositing
Cicadas are not overly selective, having been associated with over 70 different plant species, but they exhibit preferences for certain hardwoods for egg-laying, or oviposition. The trees most frequently targeted by adult females include common deciduous species such as Oak, Maple, Ash, Hickory, and Willow. Fruit trees, including Apple, Cherry, and Peach, also receive significant attention.
The nymphs feed underground for 13 or 17 years, consuming xylem fluid from the roots of a wide range of woody plants. While this long-term root parasitism generally does not cause significant harm to mature trees, it forms the basis of the cicada’s life cycle. Adults continue to feed minimally on branches, but the primary concern shifts to egg-laying damage.
Biological Reasons for Tree Preference
The choices made by female cicadas are driven by the architecture and health of the host tree, rather than just the species alone. Females actively seek out branches with high sap flow, which indicates a vigorous and healthy host for the development of their eggs.
The physical structure of the branches is also a major determining factor for successful reproduction. The female uses her spear-like ovipositor to slice into woody plant material, laying up to 20 eggs in each nest. The ideal branches for this process are those roughly 1/4 to 1/2 inch in diameter, often described as pencil-width. Broader and longer branches are selectively used because they reduce the likelihood of the twig dying back, a phenomenon called “flagging,” which can lead to egg desiccation.
Trees That Face the Greatest Risk
While cicadas prefer to lay eggs in mature hardwood species, established trees typically tolerate the damage with little long-term harm. The trees that experience the most severe effects are young saplings, newly planted trees, and recent transplants. This heightened vulnerability is due to size and age, regardless of the tree species.
A small tree’s entire canopy is often composed of the pencil-width branches that cicadas favor. Extensive oviposition scars on a sapling can effectively girdle its small branches, resulting in widespread branch dieback or even the death of the main trunk. Protecting high-risk specimens is accomplished by covering them with fine-mesh netting, ideally with openings no larger than 1/4 inch, to exclude the egg-laying females. The netting should be secured around the trunk before the emergence begins and kept in place until adult cicada activity subsides.
Trees Cicadas Generally Ignore
Certain types of trees are avoided by female cicadas due to unsuitable branch structure or chemical composition. Most conifers, such as Pines, Firs, and Spruces, are not targeted for oviposition. These cone-bearing trees often exude a sticky, resinous sap when punctured, which interferes with the female’s egg-laying process and can damage the eggs.
Other trees are ignored because their tissues are not adequately woody or firm enough for the female to successfully insert her ovipositor and deposit eggs. This category includes non-woody ornamentals and species like Ginkgo, which are considered a safe choice for planting in emergence years. Cicadas seek firm, woody material for their offspring’s initial development, making these non-preferred species less susceptible to damage.