Is rearing butterflies in captivity harming species? Moderation is key says expert

A Sudbury entomologist says that while raising and releasing butterflies can be a learning experience for both children and butterfly enthusiasts, this should be done in moderation.  

A decline in the Monarch butterfly population has led some northerners to raise and release butterflies in hopes of boosting the number that migrate to Mexico each fall. 

While this can be a valuable experience for butterfly enthusiasts, there can be downsides to this practice. Mass rearing can have adverse effects on the Monarch butterfly population and should be avoided. Here's why. 

Raising butterflies in captivity often results in butterflies not knowing how to adapt once they are released into the wild. 

Jennifer Babin-Fenske, Coordinator of EarthCare Sudbury Initiatives for the City of Greater Sudbury, has raised awareness of local wildlife and insects for over 10 years as a part of the city's EarthCare Program and Biodiversity Action Plan.

"Keeping a wild animal in captivity from birth, they often don't know how to take care of themselves in nature," said Babin-Fenske. "If we rear too many Monarchs in captivity, they are being released without exposure to the elements, predators."

Monarch butterflies rely on Milkweed for both protection and feeding. According to Babin-Fenske, mass rearing may also mean not enough habitat to support the population. This can result in a food shortage when the Monarchs migrate to Mexico.

Habitat loss can be attributed to urbanization and residents removing the invasive weed from their gardens.

Babin-Fenske suggests planting Swamp Milkweed instead, a less invasive strain of the more common species in Sudbury. This will be more sustainable in gardens and still benefit the Monarch butterfly population.

Habitat loss in Mexico is another challenge for the species. Deforestation has led to losses in the Monarch's overwintering habitat. This may be contributing to the decline in the population.  

Babin-Fenske also pointed out that in nature, survival of the fittest promotes selection of the strongest butterflies. Yet, rearing butterflies in captivity can allow the weaker to survive. This can mean other generations of genetically weaker offspring. 

"Some of the weaker individuals may have survived, when in nature they would not have," said Babin-Fenske.

She encourages people to enjoy nature and to rear butterflies as a learning experience, in moderation.

"Rearing insects can be a really interesting and educational experience for children and adults, as you see individuals grow from egg to larvae to adult," Babin-Fenske said. "We just want to be careful if we're trying to promote rearing them in mass."

As part of her role with EarthCare Sudbury, Babin-Fenske helps the program donate butterfly kits every year to schools in the region. Children have the opportunity to rear caterpillars through their lifecycle and release them to the wild. 

While this program has been on hold during the pandemic, she is hoping to have it running again next year.