You’ve probably heard the buzz that 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. Some people are obsessed with observing or documenting these periodic cicadas. Other people think they make enticing cuisine.

But the Food and Drug Administration (FDA) says if you have a shellfish allergy, you definitely don’t want to eat cicadas. They are related to shrimp and lobsters. If you see “cicada scampi,” are offered candy choc’ full of cicadas, or even see them served up raw, you may want to steer clear.

Here’s the warning:

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 a member of the Asthma and Allergy Foundation of America’s (AAFA) Medical Scientific Council, breaks down the reasons for the FDA warning:

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, the Director of the Food Allergy Center and Associate Professor of Pediatrics in the Division of Allergy and Immunology at Nationwide Children’s Hospital in Ohio, told Emily Heil of The Washington Post that allergic reactions to foods occur when people eat proteins. People with a shellfish allergy typically react to a muscle protein called tropomyosin.

“Many insects contain this tropomyosin muscle protein which is very similar to that found in shellfish,” Dr. Stukus noted. “Therefore, 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.”

There isn’t a lot of research on the risk of allergic reactions to cicadas in people with a shellfish allergy. But Dr. Stukus says when you aren’t certain of any danger, it’s best to leave cicadas out of your diet. So skip the cicadas on the menu, even though they literally may be all over the map.

Oh, and about that general “don’t eat cicadas if you have a seafood allergy” warning from the FDA? It may be broad for a reason. But it also might be a little misleading.

“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.”

The FDA may have put out the overall “seafood” language as a general precaution. But the warning is specifically for people with shellfish/crustacean allergies.

Also, 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. So if you can’t resist being around the big bug shells or the carcasses they leave behind, go wild!

“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. [Here’s an example:] If you have a lobster allergy, you can hold it in your hands and play with it all day. It’s not going to cause an allergic reaction. You just can’t eat the muscle.”