If You Need to Anesthetize a Butterfly, Here’s the Best Way to do it

Anesthesia makes life-saving procedures as pain- and stress-free as possible for the animals we love and care for. But not a lot is known about the effects of anesthesia on animals that we don’t typically consider pets – like butterflies and other invertebrates. Insects are often valuable members of nature centers, zoos and museums, but even if they’re just being evaluated in the wild, they can need anesthesia during physical examinations and injury treatment.

Samuel Tucker is a first-year anesthesia resident at North Carolina State University’s College of Veterinary Medicine. He recently published a study on the most effective way to anesthetize paper kite butterflies.

“The main reasons for anesthetizing butterflies are to enable physical exams, imaging, sample collection, or wing repair, called wing imping,” Tucker says. “And in rare cases, to facilitate euthanasia for an animal that is suffering. But there isn’t much information about the most effective way to do this in veterinary literature. So, we set out to determine the best anesthetic techniques.”

Tucker and colleagues looked at the effects of four different anesthesia methods: carbon dioxide (CO2), cooling to 2.78 degrees Celsius (37 degrees Fahrenheit), administering isoflurane via cotton ball in a closed box, and administering isoflurane via vaporizer.

The butterflies in each group were exposed until they were in a state of recumbency, either lying flat or on one side, then allowed to recover and evaluated for any post-anesthetic effects.

While the butterflies in every group achieved recumbency, the researchers found that overall, isoflurane was the most effective anesthesia method – whether in a vaporizing chamber or just on a cotton ball – due to the observed smooth inductions and recoveries.

“Cooling and CO2 may be effective but may also have the potential to be distressful to the animal,” Tucker says. “Isoflurane has the advantages of quickly producing loss of consciousness, being cost effective, portable (if needed in field settings) and the most commonly used inhalant anesthetic in veterinary anesthesia.

“Every animal deserves humane care, and this study opens the door for more work on anesthetic techniques for invertebrates.”