Cicadas pose essentially zero danger to people. They do not sting, they are not venomous, and the rare “bite” a person might experience is a case of mistaken identity by an insect that feeds exclusively on tree fluid. That said, there are a handful of real, lesser-known risks worth understanding, particularly for people with shellfish allergies or those tempted to eat cicadas during a mass emergence.
Why Cicadas Cannot Bite You in the Traditional Sense
Cicadas lack the mouthparts needed to bite a person the way a mosquito, horsefly, or even an ant can. Instead of jaws or mandibles designed to pierce skin, they have a long, straw-like structure called a stylet bundle. Adult cicadas use this apparatus to pierce woody stems and feed on xylem sap, the watery fluid that moves through tree tissue.1PubMed Central. Comparative Material and Mechanical Properties among Cicada Mouthparts: Cuticle Enhanced with Inorganic Elements Facilitates Piercing through Woody Stems for Feeding The mouthparts are reinforced with minerals to punch through bark, so they are strong, but they are engineered for a slow, precise insertion into plant tissue, not for rapidly breaking skin.
On very rare occasions, a cicada that lands on a person’s arm or hand may probe with its stylet, apparently mistaking warm skin for a tree branch. People who have experienced this describe it as a brief, sharp prick, roughly comparable to a thorn scratch. It does not inject venom, saliva toxins, or anything else harmful. The cicada realizes its mistake quickly, because human skin does not yield sap. There is no medical literature documenting serious injury from a cicada probe, and the experience is uncommon enough that most entomologists who study cicadas for decades never personally witness it.
No Venom, No Stingers, No Defensive Aggression
People often lump cicadas in with wasps and hornets because they are large, loud, and sometimes fly directly at your face. But cicadas belong to a completely different branch of the insect world. They have no stinger, produce no venom, and show no territorial or defensive behavior toward humans. When a cicada flies into you during a mass emergence, it is not attacking. Cicadas are clumsy fliers, and during emergence events when billions of them fill the air simultaneously, collisions with people, cars, and buildings are inevitable.
Their defensive strategies are passive. The main one is simply overwhelming predators with sheer numbers: so many cicadas emerge at once that birds, squirrels, and other animals physically cannot eat them all. Individual cicadas have almost no fight-or-flight response directed at large mammals. If you pick one up, it may vibrate its abdomen and produce a loud buzzing sound, which can startle you but cannot hurt you. Some people find the clawed feet slightly scratchy when a cicada grips skin, but this causes no injury.
The Shellfish Allergy Connection
The one population that should genuinely be cautious around cicadas is people with shellfish allergies, and the risk is not from being near them but from eating them. Cicadas, like shrimp, lobsters, and crabs, are arthropods. Their exoskeletons contain chitin and similar proteins that can trigger cross-reactive allergic responses in people sensitized to crustacean allergens. Research on edible insects has identified IgE-binding proteins beyond the well-known pan-allergens, meaning the overlap between insect and crustacean allergy triggers is broader than once assumed.2PubMed Central. Allergens from Edible Insects: Cross-reactivity and Effects of Processing
During major periodical cicada emergences, social media fills with recipes for cicada tacos, tempura cicadas, and cicada stir-fries. The FDA has even issued informal guidance reminding people with shellfish allergies to avoid eating cicadas. If you carry an epinephrine auto-injector for crustacean allergy, treat cicadas the same way you would treat shrimp. This is not a theoretical concern; the shared protein structures are well documented in allergy research, and a reaction could be severe.
Are Cicadas Safe to Eat for Everyone Else?
For people without shellfish or arthropod allergies, cicadas are nutritious and have been eaten by humans across cultures for centuries. Nutritional analysis of cicadas at different life stages shows that protein content is substantial, and essential amino acids increase as the insect matures. Adults contain a higher index of essential amino acids than nymphs. Cicadas also contain notable amounts of eicosapentaenoic acid, an omega-3 fatty acid, with concentrations varying depending on developmental stage.3PubMed Central. Chemical composition and nutritional profile of cicada (Meimuna opalifera Walker) at different developmental stages: Implications for functional food applications
The catch is food safety. Wild-caught cicadas carry bacteria on their surfaces and inside their bodies. Studies of wild-caught cicadas found standard plate counts ranging from about 3 to 9 log CFU per gram, and Enterobacteriaceae were detected on most specimens. Many of the bacterial species identified were biosafety level 2 pathogens or opportunistic pathogens. Bacterial counts rose rapidly in dead cicadas stored at room temperature.4Brill / Journal of Insects as Food and Feed. Hygienic indicator bacteria in the 2 species of wild-caught Japanese cicadas, large brown cicadas and robust cicadas In practical terms, this means you should cook cicadas thoroughly if you plan to eat them, collect them while they are alive or freshly dead, and avoid eating ones that have been sitting on the ground in the heat. Treating them like raw poultry from a food-safety standpoint is a reasonable approach.
Timing matters too. Many cicada enthusiasts recommend collecting newly emerged adults, called tenerals, while they are still soft and pale before their exoskeleton hardens. These are said to have a milder flavor and softer texture. Once the shell darkens and stiffens, the insect becomes crunchier and more fibrous, which some people enjoy and others find unpleasant.
Do Cicadas Carry Diseases That Spread to Humans?
Cicadas are not known to transmit any diseases to humans. Unlike mosquitoes, ticks, or fleas, they do not feed on blood and therefore have no mechanism for picking up human pathogens and delivering them to the next person. The bacteria they carry, as described above, are environmental microbes associated with soil and plant material, not specialized human-disease agents. You can handle cicadas with bare hands without worrying about disease transmission. Washing your hands afterward is sensible in the same way it is sensible after handling any outdoor animal, but no special precautions are needed.
Cicadas do host their own parasites, most famously a fungus called Massospora cicadina that infects periodical cicadas, replacing their abdomens with masses of fungal spores. Infected cicadas sometimes behave strangely, continuing to fly and attempt to mate despite having lost much of their body. This fungus is specific to cicadas and poses no threat to humans, other animals, or garden plants. You might find it unsettling to see, but it is biologically harmless to everything except the cicada.
Pesticide and Heavy Metal Concerns
Because periodical cicada nymphs spend 13 or 17 years underground feeding on root fluids, some people worry they might accumulate pesticides or heavy metals over that long period. Research on 17-year cicadas in Maryland found that organochlorine and heavy metal concentrations were well below levels known to be harmful to birds, and cicadas contained metal concentrations similar to or less than other local invertebrates.5PubMed. Organochlorines and heavy metals in 17-year cicadas pose no apparent dietary threat to birds Even cicadas collected from the median of a major highway did not contain more lead than those from non-traffic sites. Copper and lead were slightly elevated at one location, likely due to sewage plant effluent from river flooding, but still not at dangerous levels.5PubMed. Organochlorines and heavy metals in 17-year cicadas pose no apparent dietary threat to birds
That said, common sense applies. Avoid collecting cicadas from areas that have been recently sprayed with insecticides, near industrial sites, or from lawns treated with chemical fertilizers and herbicides. The long underground period does not make cicadas uniquely contaminated, but it does not make them immune to surface-level chemical exposure either. If you are foraging cicadas from a well-maintained suburban lawn that gets regular pesticide applications, those chemicals could be on or in the insects.
The Noise Factor
If cicadas are going to “hurt” you in any literal sense, it is your eardrums that are most at risk. Male cicadas produce sound using specialized structures called tymbals on their abdomens, and the collective chorus during a mass emergence can reach roughly 90 to 100 decibels at close range. That is comparable to a gas-powered lawn mower or a motorcycle. Sustained exposure at those levels can contribute to temporary hearing discomfort or, in prolonged cases over days and weeks, mild hearing fatigue.
Most people will not experience lasting hearing damage from cicadas simply because the sound is intermittent and you can move away from the loudest trees. But if you work outdoors all day in an area with a heavy emergence, wearing ear protection is not an unreasonable idea. The sound is particularly intense in late morning and early afternoon, when temperatures are highest and males are most actively calling.
Driving Hazards During Mass Emergences
An underappreciated risk from periodical cicadas is the driving hazard they create. When billions of cicadas emerge simultaneously, roads near wooded areas can become slippery with crushed insects. Windshields get smeared, reducing visibility. Cicadas fly into car vents and sometimes into open windows, startling drivers. In areas with dense emergences, local authorities have occasionally noted minor upticks in fender-bender accidents.
Keeping your windows up, using your windshield washer fluid liberally, and slowing down on tree-lined roads during peak emergence are practical steps. The flying is worst during warm daylight hours. If you ride a motorcycle or bicycle, a full-face shield or glasses are worth wearing. A cicada hitting exposed skin at speed can sting, not from any biological mechanism but from sheer impact, in the same way a large beetle or june bug would.
Pets and Cicadas
Dogs, in particular, tend to gorge themselves on cicadas during mass emergences. The insects are slow-moving, abundant, and apparently tasty to many dogs. In small quantities, cicadas are harmless to pets. In large quantities, the exoskeletons can cause gastrointestinal upset: vomiting, diarrhea, or constipation from the indigestible chitin. Veterinary clinics in cicada-heavy regions report a noticeable increase in visits for GI distress during emergence years.
The concern is mechanical, not toxic. Cicadas are not poisonous to dogs or cats. But a dog that eats 50 of them in an afternoon may regret it. Keep an eye on enthusiastic eaters, and if your dog starts vomiting repeatedly or shows signs of intestinal blockage like lethargy and loss of appetite, a vet visit is warranted. Cats are generally less interested in cicadas, though some will catch and eat them with similar, usually milder, consequences.
Why Cicadas Seem Scarier Than They Are
Much of the anxiety around cicadas comes from the sheer spectacle of a periodical emergence. Annual cicadas appear in manageable numbers every summer, and most people barely notice them beyond their evening buzzing. Periodical cicadas, by contrast, emerge in synchronized broods that can produce hundreds of thousands of individuals per acre of forest. The ground churns with nymphs, the air fills with flying adults, and the decaying bodies pile up and smell. It is viscerally overwhelming, and the human brain tends to interpret “overwhelming swarm of large insects” as dangerous.
But the entire evolutionary strategy of periodical cicadas depends on being harmless and abundant. They survive not by fighting back but by flooding the environment so thoroughly that predators cannot possibly eat them all. The remaining cicadas mate, lay eggs, and die within a few weeks. The spectacle is temporary. For anyone who finds the experience genuinely distressing, staying indoors during peak activity hours and keeping doors and windows closed is effective. The emergence typically lasts four to six weeks, with the heaviest activity compressed into about two or three weeks.
Cicadas and Garden Plants
While cicadas do not harm humans, they can damage young trees. Female cicadas use a saw-like ovipositor to cut slits into pencil-thin twigs, where they deposit their eggs. This causes the twig tips to brown and die, a phenomenon called “flagging.” On mature trees, this natural pruning is cosmetically annoying but not harmful to the tree’s long-term health. On recently planted saplings or very young ornamental trees, the accumulated damage from hundreds of egg-laying cuts can be serious enough to kill the tree.
If you planted new trees in the last year or two and a periodical cicada emergence is approaching, wrapping them in fine netting with mesh openings smaller than about half an inch is the standard recommendation. Insecticide spraying is ineffective against cicadas during mass emergences because the sheer numbers make chemical control impractical, and broad-spectrum sprays kill beneficial insects along with the cicadas. The netting comes off after the emergence ends, and the trees continue growing normally.