Revised Handout - Raising Monarchs: Why or Why Not?
The MJV has revised and retitled our existing Rearing Monarchs Responsibly handout to reflect additional information about raising monarchs; it is now Raising Monarchs: Why or Why Not?. Here we share content from the handout, or read the full handout here. For outreach activities, we encourage you to download, print, and share MJV handouts.
Raising Monarchs and Conservation
In the face of monarch population declines, passionate conservationists are fighting to save this winged icon. Rearing monarchs in classrooms and homes has been a valuable educational tool for teachers and for citizen science. Unlike many wildlife species, monarchs are easily reared and offer an up-close look at metamorphosis. As monarch populations have declined, some people have promoted rearing and releasing, or even purchasing, monarchs on a large scale as an attempt to boost wild populations.
There is a lack of scientific evidence that monarch rearing actually results in overall population increases, and it is known to carry risks. Many experts do not support large scale captive rearing for conservation purposes. Potential risks include releasing monarchs that are adapted to captive conditions, increasing parasites and disease in wild monarch populations, and making it more difficult to understand natural monarch distributions. Recommended strategies that do support monarch populations in the long-term include creating or improving habitat, minimizing monarch and habitat exposure to pesticides, and participating in citizen science or other research.
However, there is little risk in responsibly raising a few monarchs for enjoyment, education, or citizen science, which can lead to stronger human connections with and better understanding of this amazing species.
Captive rearing often involves raising monarchs at higher densities than they occur in the wild, and re-use of the same containers over and over again. Monarchs did not evolve under high density conditions, and thus caterpillars reared in close proximity to one another are highly susceptible to disease transmission. Re-use of the same rearing materials can allow parasites and pathogens to accumulate over time and inadvertently spread disease. If unhealthy monarchs survive rearing and are released into the wild, they could transmit diseases or parasites to wild monarchs, risking adverse effects on an already vulnerable population. Unhealthy monarchs may also experience lower survival, reproduction, and migration success relative to healthy butterflies.
Natural Distribution Concerns
Effective conservation requires understanding population distributions. If monarchs are seen in unusual places or times, we can learn about their movement patterns and habitat use. However, if the observer doesn’t know if an unusual sighting involves a captive-reared monarch, our ability to understand natural population distributions is compromised.
Species bred in captivity can adapt to captive settings in just a few generations. Differences in temperature, food, predation and density between wild and captive settings can favor different traits related to development rate, body size, feeding behavior, and defenses. Frankham, 2008 suggests these genetic adaptations are overwhelmingly harmful when offspring of multiple generations of captive breeding are returned to the wild.
Rearing Monarchs Responsibly
For those who do rear monarchs for educational or citizen science purposes, we offer the following guidance for responsible rearing. Below are our tips to do so responsibly, and more detailed information is available in the revised handout.
- Keep the cage clean. Rearing containers need to be cleaned of frass (waste) and old milkweed daily to prevent mold growth. Clean containers with a 20% bleach solution and rinse before putting monarchs inside.
- Keep milkweed fresh. Add fresh milkweed every day to ensure monarch larvae have quality food.
- Avoid extreme temperature and moisture conditions. Keep rearing containers out of direct sunlight and make sure that there is not too much moisture (paper towel should be moist, but not dripping wet). Temperatures that are too cold will delay monarch development. If the container is in direct sun, it will act like a greenhouse, and heat up to potentially lethal temperatures.
- Be conscious of disease. Viral and bacterial infections spread very quickly from one caterpillar to another, so keep containers clean and sterilize them often.
- Submit observations of all reared monarch to citizen science. The Monarch Larva Monitoring Project collects observations on survival of monarchs, Project Monarch Health tests adult monarchs for the OE parasite, and many other citizen science programs may have use for your data.
Raising Monarchs: Why or Why Not?
So, what’s the answer to the question: why rear or not? People who wish to rear monarchs are encouraged to do so in small numbers, for outreach, personal enjoyment, or citizen science. With the risks associated with large-scale rearing for release into the wild, raising large numbers of monarchs in captivity is not a recommended conservation strategy. Creating habitat, rich in milkweed and nectar sources, is critical in our efforts to support self-sustaining monarch populations.
The Monarch Joint Venture is a national partnership of federal and state agencies, non-governmental organizations, businesses and academic programs working together to conserve the monarch butterfly migration. The content in this email does not necessarily reflect the positions of all Monarch Joint Venture partners. Header photo by Tom Collins.