Cicadas are large, winged insects that emerge either annually or on multi-year cycles, such as the 13-year or 17-year periodical broods. Their sudden, mass appearances often raise public concern about potential threats to people and animals. These insects are primarily interested in mating and feeding on plant fluids, and they pose virtually no danger to humans or household pets.
Physical Interactions with Humans
Cicadas do not have the physical mechanisms to bite or sting a person defensively, as they lack mandibles, which are the chewing mouthparts found in biting insects. They also do not possess a stinger or venom, making it impossible for them to inflict a painful or medically significant injury. Any sensation of being “poked” or “pricked” is accidental, resulting from the cicada’s primary feeding tool, the proboscis, or beak.
The proboscis is a straw-like mouthpart designed for piercing plant stems and sucking up sap, not for drawing blood. If a cicada lands on a person and attempts to probe the skin, it is simply mistaking the tissue for a plant surface while searching for a drink. This action is usually harmless and cannot penetrate human skin deeply, often feeling like a mild pinch or scratch at most. The insect’s only goal is to find a source of tree fluid, not to engage with or attack a person.
While physically harmless, cicadas produce one notable environmental hazard: extreme noise. Male cicadas generate mating calls using specialized organs called tymbals, producing sounds that can reach levels between 90 and over 100 decibels. This volume is comparable to a power lawnmower or a chainsaw and can be loud enough to cause discomfort. Prolonged exposure to such high decibel levels may require hearing protection, but the sound itself does not transmit disease or cause physical trauma.
Health Risks and Pathogen Transmission
A common concern is whether cicadas can carry or transmit diseases to humans, but scientific evidence confirms they are not vectors for human pathogens. Unlike mosquitoes or ticks, cicadas do not feed on blood and therefore cannot spread viruses, bacteria, or other parasites between people. The most common health issue related to their presence is the possibility of mild allergic reactions. These reactions are typically a response to the fine dust created by the immense volume of shed exoskeletons (molting debris) left behind as the nymphs transform into adults.
A visually alarming, yet harmless, biological phenomenon involves the parasitic fungus Massospora cicadina. This fungus infects some periodical cicadas, replacing the insect’s abdomen with a chalky white or yellowish plug of fungal spores. Infected cicadas have been observed to contain compounds like cathinone, a type of amphetamine, which is believed to contribute to their hyperactive behavior. Though this fungus is non-transmissible to humans, people should avoid consuming these infected insects due to the presence of various mycotoxins identified within the fungal plug.
Impact on Pets and Landscape
Cicadas are non-toxic to both cats and dogs, meaning they do not contain harmful chemical toxins. However, pets are often drawn to the crunchy, readily available insects and may eat them in large quantities. The primary risk is gastrointestinal upset, as the insects’ hard, chitinous exoskeletons are difficult to digest, potentially leading to vomiting, diarrhea, or, in rare cases, a digestive tract obstruction.
The only genuine threat cicadas pose is to the landscape, specifically to young trees and shrubs. Female cicadas cause damage during oviposition (laying eggs), using an ovipositor to slice slits into small, pencil-sized branches. The repeated incisions weaken the branch tips, causing the leaves to wilt and the ends of the branches to die, a condition known as “flagging.” Mature, established trees can easily withstand this natural pruning, but vulnerable saplings may require protective netting to prevent serious injury.