In a rare occurrence, a trillion cicadas from two different broods are expected to begin appearing in the Midwest and Southeast regions of the United States at the end of April. These are a type of insect that live underground and then emerge from the soil every 17 years to mate. And there’s a lot of them.

Kids may be fascinated with the cicadas – playing with them, watching them, or closely looking at their shells. But the Food and Drug Administration (FDA) has an important message: If your child has a shellfish allergy, make sure they don’t eat cicadas (as tempting as that might be for some). The warning goes for adults too.

If your child has a shellfish allergy teach them not to put cicadas or other insects in their mouth or eat them. Here’s why:

Yep! We have to say it!

Don't eat #cicadas if you're allergic to seafood as these insects share a family relation to shrimp and lobsters. https://t.co/UBg7CwrObN pic.twitter.com/3qn7czNg53

— U.S. FDA (@US_FDA) June 2, 2021

David Stukus, MD and member of the Asthma and Allergy Foundation of America’s (AAFA) Medical Scientific Council, explains:  

Here’s the deal:
🍤People with shrimp, crab & lobster allergy reaction to a muscle protein called tropomyosin
🦞They do not react to the shell
🪰Cicadas also have tropomyosin

⚠️If you have a shellfish allergy, it’s not advisable to eat cicadas.
Casual exposure poses no risk.👍 https://t.co/9HfJAklWum

— Dr. Dave Stukus (@AllergyKidsDoc) June 2, 2021

Dr. Stukus explains people with a shellfish allergy usually react to a muscle protein called tropomyosin. A lot of insects have the same muscle protein.

“If you have a shellfish allergy, it is probably not a good idea to eat cicadas or other insects without at least first discussing it with your allergist,” says Stukus.

Study is limited on this. But in her research, Mahboobeh Mahdavinia, MD and PhD at Rush University Medical Center in Chicago, says studies show cockroach exposure could lead to the development of shellfish allergy in kids.

“The immune system can confuse certain proteins in seafood with similar proteins that are present in the muscles of cockroaches that commonly elicit an allergic response," says Dr. Mahdavinia. She also notes dust mites and cockroaches are two common household allergens that have tropomyosin. There could be a link between inhaling the protein and shellfish allergy.

Dr. Mahdavinia’s research also shows Black children have higher rates of shellfish allergy compared to white children. This could be due to social determinants of health, including structural racism.

Don’t let general seafood warnings related to cicadas confuse you.

When the FDA put out its cicada warning, they directed it toward anyone with seafood allergies. But it really should have been directed at anyone with a shellfish allergy.

“People who have allergies to finned fish like salmon or tuna tend to react to other proteins which don’t necessarily cross react,” explains Dr. Stukus. “If you have a seafood allergy, you don’t always necessarily have to always avoid crustaceans and finned fish.”

But there is good news for kids with a shellfish allergy who still want to check out cicadas up close.

There’s no muscle protein in the cicada’s shell. The only time cicadas pose a risk for people with a shellfish allergy is if you eat them. It’s OK for kids to keep observing the big bugs so long as they don’t consume them.

“Cicadas are not going to bother anybody with shellfish allergy unless they actively go out of their way to capture them and then ingest them,” Dr. Stukus shares. “That’s the risk for reaction. You can have millions of them on your trees and in your yard − you are going to be fine. The shells they leave behind will not cause any risk for people who want to collect the shells.”

Kids With Food Allergies is the food allergy division of AAFA.