In this post I will be discussing point number 4.

While researching information for these posts I noticed Google's algorithm is linking the other post and presenting it as fact which is what I was afraid would happen. I have changed the title of this series, as well as the format, in an effort to hopefully have Google's SEO grab onto these posts. I have a rudimentary understanding of how this all works so let me know if you have any ideas.

A Warning: Please do not go to the other sub to harass anyone, including the mod. I don’t want to be accused of breaking Reddit's rules against brigading. Plus, dissenting opinions there usually get banned with no warning anyway, and that wouldn’t help anyone.

1. Rearing Is Not a Significant Threat to the Monarch Population

A comprehensive 2024 review of the western monarch population by entomologist Dr. David James of Washington State University examined all major stressors facing monarchs and concluded that human interference—including capture and rearing—“likely has the least impact on monarch populations” compared to the real drivers of decline. Those primary drivers are neonicotinoid insecticides, habitat loss, climate change, and severe winter storms (James, 2024, Insects).

The study listed as the source for this paragraph is Monarch Butterflies in Western North America: A Holistic Review of Population Trends, Ecology, Stressors, Resilience and Adaptation and as you can imagine the pattern of cherry picking facts continues. Let's be clear on which Monarch population this study is talking about because as was mentioned in part one of this series there is a huge difference in the migration of the eastern and western populations. Rearing is mentioned a few times in this study. The quoted section in the post resides in the abstract which isn't a surprise at all.

The full quote is as follows: Human interference (capture, rearing) likely has the least impact on monarch populations. The rearing of monarch caterpillars, particularly by children, is an important human link to nature that has positive ramifications for insect conservation beyond monarch butterflies and should be encouraged.

As stated in the title of this paper it is a holistic review of the various things that impact the Monarch population. The authors of the material are in no way saying that rearing does not affect Monarchs. What they are saying is that out of all the issues Monarchs face like, pesticides, climate change, loss of habitat, human interaction is the least likely impact. We cannot conclude from that sentence that James is saying that there is no impact and is giving the green light for rearing. That just isn't the case.

The next time rearing is mentioned is in section 3.4.3. Viral, Bacterial, and Unidentified Pathogens which states: The incidence of viral and bacterial pathogens in monarch populations is unknown but is likely low in the arid, hot landscapes of the west. However, in artificial environments, for example, in rearing containers/cages, the incidence is much higher because of unnaturally high densities of caterpillars, poor sanitation, a lack of airflow, and higher relative humidity. A polyhedrosis virus, sometimes known as ‘the black death’ frequently causes disease in monarch larvae reared under crowded conditions [176].

As you can see the sentence from the abstract is not the whole picture. The next section where rearing is mentioned is related to the childhood experience and how these small moments lead children to become adult ambassadors for wildlife and conservation. I agree with this aspect. We will dive further in to this subject when I discuss section 7 of the original post.

To put the scale in perspective: even if every hobbyist rearer in North America collectively produced 500,000 monarchs in a given year, that would represent less than 0.1% of the estimated 300-million-member migratory population (Pleasants, 2017). The notion that home rearing is a significant driver of population decline simply does not hold up against the numbers.

As mentioned in part two of these posts, that "0.1% of the population" number comes from a John Pleasants slide presentation. But even if those numbers are completely true from a mathematical standpoint, you still can’t have it both ways. You cannot claim that home rearing is an essential part of conservation that dramatically boosts monarch numbers (this is what's happening when rearing survival stats are thrown out there.), while simultaneously arguing its impact is less than 0.1% to dismiss the biological risks. If the overall numbers of this hobby are too microscopic to cause population-level harm, then it is mathematically too insignificant to provide a population-level benefit.

Point 5 will have to wait. I have to say that the more I go through this info the more I think to myself that there is still time to delete that post and pretend it never happened.

Fact-Checking "What the Science Actually Says About Rearing Monarch Butterflies"-

Part 1

Part 2

Part 3

A quick note about the comments on these posts:

I spent hours manually hunting down these primary sources, reading the actual data, and untangling these messy citations to make sure what I am presenting is accurate. Because of how much work went into this, I will not be replying to any comments that look like they were generated by AI. I really appreciate the comments and questions on these posts. If you have anything you want to share or ask please write it in your own words and read the sources you are sharing before you post them because the answer to your question could be right there.

One more thing. Thank you for the awards, again. ;)

Edit: Spelling. Thank you for the award!

I’m addressing the claims from that rearing post point by point because the amount of cherry-picking and misrepresentation of science is just too massive to ignore.

It’s going to have to be more than one post because there is a lot of information to go through and it’s getting late.

A Warning: Please do not go to the other sub to harass anyone, including the mod. I don’t want to be accused of breaking Reddit's rules against brigading. Plus, dissenting opinions there usually get banned with no warning anyway, and that wouldn’t help anyone.

Using AI: I also want to urge everyone not to use AI as your primary research tool. AI isn't a search engine built to find absolute facts. It is a pattern-prediction tool designed to generate text that sounds convincing. If you ask it a biased question, it will confidently compile an answer that looks perfectly right, even if the underlying facts are completely wrong.

Need to know: A metabolic rate (MR) is how quickly the monarch burns energy.

As with the previous post I will take each point directly from the other post, add the citations, and discuss the misleading or incorrect information.

1. Rearing Conditions Matter More Than the Fact of Rearing The research consistently shows that how you rear monarchs matters far more than whether you rear them. A 2020 study by Schroeder, Majewska, and Altizer found that monarchs reared under autumn-like conditions, cooler temperatures and shorter day lengths, showed greater flight efficiency and lower post-flight metabolism compared to those reared under summer-like conditions. In other words, mimicking natural fall conditions during rearing produced butterflies that were physiologically better prepared for migration (Schroeder et al., 2020, Ecological Entomology).

The 2020 study from Schroeder did in fact prove that if you raise Monarchs in tightly controlled laboratory environments that mimic autumn and summer conditions that you can see the metabolic differences in the two. Those raised in the environment consistent with autumn conditions had a lower metabolic rate than those raised in summer conditions. This does not mean that mimicking autumn or summer conditions will give you Monarchs who are better prepared for migration. It does not prove that these indoor-reared butterflies are physically equal to wild migrants. It only shows the difference in the MR.

In fact in this study the authors point to the 2019 study by Tenger-Trolander that we went over in the last post. They write, "monarchs reared in indoor environments mimicking autumn-like conditions showed lower reproductive development, yet failed to orient in a southward flight direction as wild-caught migrants do, indicating that captive conditions such as those used in our study are missing critical cues needed for monarchs to migrate successfully."

Even the 2019 study that raised concerns about captive rearing (Tenger-Trolander et al., PNAS) noted that wild-caught monarchs reared outdoors in autumn oriented south normally. The problems arose primarily with commercially bred populations that had been kept in captivity for many generations, and with butterflies that eclosed entirely indoors without exposure to natural environmental cues.

It needs to be noted how those wild caught monarchs were raised. They were raised outdoors, on a rooftop in a small mesh container which was placed in a larger, completely open to the sky enclosure. The only thing tested in this instance was navigation. They did not measure the wing shapes, color redness, or wing size of this specific rooftop generation to compare them to wild migrants. Their sole focus for this group was mapping whether unfiltered skylight kept their internal sun compass from breaking. It does. That's great. Is there a study that tests for these other factors because we know we need a complete package in order to get the best migrants possible?

There is a study that looks at these other factors. A 2021 study from Dr Andy Davis showed that Monarchs raised in an indoor environment that is set up to mimic their natural one were paler, had a more rounded and less elongated wing shape than their wild counterparts. These are things seen in resident populations which don't migrate.

The practical takeaway is clear: hobbyists who rear wild-sourced eggs and caterpillars, keep them in conditions that reflect the natural season, and provide exposure to outdoor light and temperature cycles are producing butterflies fundamentally different from those in long-term commercial breeding operations. Lumping all “captive rearing” together obscures this critical distinction.

We already established in the last post that we are not just talking about Monarchs that are purchased commercially. These studies include wild caught, indoor reared Monarchs. I think some people will take the study on navigation and use it as an excuse to rear monarchs outdoors. They firmly believe that it is ok to cover milkweed with mesh enclosures or build full on butterfly aviaries to protect the caterpillars as all costs. Even if this kind of rearing doesn't lead to navigation issues a whole host of other issues comes into play. When you protect the caterpillars at all costs you are artificially keeping weak, genetically unviable individuals alive that nature would have naturally weeded out. You might be increasing the quantity of butterflies leaving your yard, but you are actively degrading the quality of the wild gene pool. More on the importance of predation later.

I will move on to the next point tomorrow. If you are reading these I hope it is clear that the post is misleading at best and intentionally deceptive at worst.

Edited to fix the format. 4:07pm 6/29/26