Introduction to Cicadas
Cicadas are fascinating insects with a distinct sound, often associated with hot summer days. While they are a subject of interest for many entomologists, they can also be a concern for gardeners, landscapers, and homeowners, particularly when their numbers increase significantly during certain years. Understanding the biology, behavior, and life cycle of cicadas is essential for anyone looking to prevent potential damage to their trees.
Understanding Cicada Biology
Physical Characteristics
Cicadas are large insects, usually around 1 to 2 inches long, with prominent eyes and transparent wings. They are best known for their unique sound, produced by males to attract females, using specialized structures called tymbals.
Types of Cicadas
There are over 3,000 species of cicadas, but they can be broadly categorized into two types: annual cicadas and periodical cicadas. Annual cicadas appear every year, whereas periodical cicadas emerge in large numbers every 13 or 17 years, depending on the species.
Cicada Lifecycle
Cicadas have a unique and fascinating lifecycle. It consists of several stages, each of which plays a role in the potential impact on trees.
Egg Stage
Female cicadas lay their eggs in the tender twigs and branches of various tree species. They use a specialized organ called an ovipositor to cut slits into the wood, where the eggs are then deposited. This is the first stage where they may cause damage to the tree.
Nymph Stage
Once the eggs hatch, the nymphs drop to the ground and burrow into the soil, where they feed on tree roots. They will remain underground for several years, depending on the type of cicada, feeding and growing until they are ready to emerge.
Adult Stage
The adult stage is the most recognizable phase of the cicada’s life. This is when they emerge from the ground, shed their exoskeleton, mate, and lay eggs. The sound associated with cicadas is most pronounced during this stage.
Damage Caused by Cicadas
Oviposition Damage
The process of laying eggs can cause noticeable damage to young trees. The slits made by the female cicada can weaken the twigs and branches, leading to breakage and a phenomenon called “flagging,” where the ends of branches die and turn brown.
Root Feeding
The nymph stage’s root feeding generally does not cause significant damage to established trees, but it can be a concern for newly planted or young trees with underdeveloped root systems.
Aesthetic Impact
The sheer numbers of cicadas during a mass emergence, particularly with periodical cicadas, can be overwhelming and may be considered a nuisance by some people. This is more of an aesthetic and comfort issue rather than actual harm to the trees.
Preventing Cicada Damage to Trees
Tree Selection
Certain tree species are more attractive to cicadas for egg-laying. Knowing which trees are most susceptible and choosing alternative species can be a proactive approach to minimizing potential damage.
Tree Wrapping
For young or vulnerable trees, wrapping the trunk and branches with fine mesh or netting can prevent female cicadas from accessing the areas where they typically lay eggs. It’s essential to use a material that allows light and air flow and to remove it once the risk has passed.
Proper Watering and Care
Healthy trees are generally more resilient to cicada damage. Regular watering, fertilization, and proper pruning can keep trees strong and better able to recover from any damage that does occur.
Chemical Control
In extreme cases, insecticides may be used to control cicada populations. It’s typically not recommended for home gardeners, as it requires careful timing and application, and may have unintended effects on other non-target organisms.
Myths and Misconceptions About Cicadas
Cicadas are often misunderstood, and there are many myths and misconceptions associated with them. They are not locusts and do not consume leaves or other above-ground plant parts. Their primary impact on trees is through egg-laying and root feeding as nymphs.
Monitoring and Responding to Cicada Emergence
Being aware of the timing of cicada emergence, particularly for periodical cicadas in your area, allows for timely preventive measures. Local extension services, garden centers, and entomology websites often provide information and alerts about expected emergences.
The Role of Cicadas in the Ecosystem
It’s essential to recognize that cicadas play a vital role in the ecosystem. They provide food for various animals, including birds, mammals, and other insects. The tunnels dug by nymphs can aerate the soil, and the decaying bodies of adult cicadas add nutrients back into the environment.
Conclusion
While cicadas can be a concern for tree health, particularly for young or vulnerable trees, understanding their biology, behavior, and lifecycle allows for effective prevention and management. The damage they cause is typically minimal in the grand scheme of things, and their role in the ecosystem adds to the complexity and richness of our natural world. Taking a balanced and informed approach to dealing with cicadas can minimize their impact while allowing for appreciation of these unique and intriguing insects.
