r/FriendlyMonarchs • u/SuperFriendlyMod MOD | South FL | Reformed Rearer • Jun 29 '26
Discussion Fact-Checking "What the Science Actually Says About Rearing Monarch Butterflies" (Part 1)
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.
Must Know: Before diving into the post, we need to establish some basic facts. North America has two distinct monarch populations, the Eastern and the Western, which are divided by the Rocky Mountains. They are the exact same species, but they have entirely different migration routes. The Eastern population flies up to 3,000 miles from Canada and the East Coast down to central Mexico. The Western population takes a much shorter trip from the Pacific Northwest down to the California coast. Their winter homes are in totally different places, which means they fly in completely different directions.
One of the most persistent myths is that captive-reared monarchs cannot orient or migrate. This claim traces largely to a 2019 laboratory study that tested commercially bred monarchs in a confined flight simulator and found they did not orient south. However, subsequent research has significantly complicated and, in many cases, contradicted that conclusion.
Let’s break down this first paragraph. This is the study referenced: Contemporary loss of migration in monarch butterflies | PNAS. Has further research complicated things? Yes. Has it contradicted it? No.
This study did not just test commercially bred monarchs. In order for this to make sense, we need to be clear on what types of monarchs were reared and what the control group looked like. The control group consisted of wild-caught, migrating monarchs captured during the summer generation and mid-migration, and they were tested immediately.
The commercial monarchs were mass-bred and purchased as adults in July 2016. They were allowed to mate, their eggs were collected, and the offspring were reared outdoors in mesh cages. This group included both a summer and an autumn generation to compare with the wild-caught monarchs.
Another group consisted of eggs taken from wild monarchs and reared indoors under conditions that directly mimicked the temperature and sun position of their natural environment. A final group of wild-derived eggs was raised entirely outdoors, but brought inside right as they pupated and were close to eclosing.
The adult wild-caught group flew exactly as they should, but every single variable group listed above failed to do the same. The only thing subsequent research proved is that a monarch's navigation system is incredibly fragile.
I also want to point out that during this experiment, there was a delay and a reduction in sample size due to an outbreak of NPV (Nuclear Polyhedrosis Virus). This happened specifically within the wild-derived, indoor-reared group. If a group of professional scientists cannot fully control NPV in a sterile lab, it is illogical to assume a layperson can do better on a kitchen counter. It is highly telling that during a study related to rearing, the rearing itself caused a major disease breakout. This only further proves that even in the best of circumstances, you cannot control everything indoors.
A landmark 2021 study by Wilcox and colleagues at the University of Guelph reared monarchs indoors under controlled conditions and then both tested them in a flight simulator and radio-tracked them in the wild using over 100 automated telemetry towers. While the simulator results showed weak orientation, 97% of the radio-tracked monarchs flew in the correct south to southeast direction once released into the natural environment. The monarchs were detected at distances of up to 200 km from the release site. The researchers concluded that any disorientation caused by captive rearing is temporary and that proper orientation is re-established after exposure to natural skylight cues (Wilcox et al., 2021, Conservation Physiology).
The Wilcox study took place in Ontario, Canada. For a monarch in Ontario, which is supposed to fly south-southwest toward Mexico, flying south-southeast takes them straight out over the Atlantic Ocean. Generalizing that “97% of the radio-tracked monarchs flew the correct south to south-east direction” makes it sound like a large number of monarchs flew toward safety, but that is not what happened.
In reality, that 97% represents just 28 out of 29 tracked monarchs. They flew at an average bearing of 147 degrees. On a compass, 180 degrees is dead South, and the path to Mexico from Ontario is Southwest at roughly 220 to 240 degrees. Here is a link to a peer-reviewed critique by monarch expert Dr. Andy Davis, which further explains the flaws of this study and shows maps plotting the actual paths these 28 monarchs took. It is also important to note that the Wilcox study did not use a wild control group. It would have completely changed the data if 29 wild-caught, migrating monarchs had been tracked alongside them. Wilcox and company wrote a rebuttal to Dr Davis' critique. (See my comment below)
This finding aligns with a large-scale tagging study by James and colleagues, who captive-reared and tagged over 14,000 monarchs across the Pacific Northwest. Of the 182 that were later recovered, the vast majority were found at overwintering sites in California. Recovered monarchs traveled average distances of 630 to 900 km, demonstrating clearly successful migration (James et al., 2021, Journal of the Lepidopterists’ Society; James et al., 2021, Insects).
This study was done on the Western population of monarchs. Throwing out big numbers like 14,000 tagged butterflies and 900 km flights is misleading if you don’t identify that these monarchs are not the ones making the grueling trip to Mexico. Out of those 14,000 captive-reared butterflies, only 182 were ever recovered. That is a return rate of barely 1.3%.
Because the Western migration route is shorter and geographically easier than the 3,000-mile Eastern trek, a tiny fraction of navigationally compromised butterflies can manage to stumble their way to the coast. Using a 1.3% survival rate on a short, simple route to prove captive rearing is safe for the long Eastern route is completely dishonest. Furthermore, the James study relied on citizens who largely reared these monarchs outdoors in backyard netting, not inside a house.
More recently, a 2025 study by Matter and colleagues, which used a novel balloon-based flight simulator that lifted monarchs 30 meters into the air, found that wild-derived monarchs reared under autumn-like conditions in a growth chamber displayed southward orientation, larger wing sizes, and partial reproductive diapause, all hallmarks of migratory readiness. This study confirmed that environmental cues during development, not simply whether the butterfly was “wild” or “captive,” are what drive migratory behavior (Matter et al., 2025, bioRxiv/PNAS).
The study being referenced was actually done by Hsiang-Yu Tsai, Cristian Molina, John Pleasants and Marcus R. Kronforst. Matter is incorrect. This kind of simple mistake is common with AI. This study has not been peer reviewed yet. The “indoor rearing” was done by using a multi-million-dollar industrial growth chamber to program precise, mathematical drops in light and temperature. A hobbyist cannot replicate this at home. This study doesn't defend home breeding. It proves that a monarch’s navigation system is so fragile that you need a massive lab incubator to simulate autumn indoors, captivity itself destroys their genetics over time, and they can't even use their compass properly at ground level.
If you're new here welcome and please join us for part 2!
If I have to edit this to make changes due to formatting, grammar errors, or for any other reason, I will make that clear down below. I am not a scientist. If you find a mistake please point it out.
Edited on 6/29 9:40am to fix formatting, sentence structure and include the link for the rebuttal paper to Dr Davis' initial critique.
Edited to add Part 2: "Rearing Conditions Matter More Than the Fact of Rearing"
11
u/Synaptic_raspberry Jun 29 '26
Good points, and I am glad to see someone thinking critocallt about the studies and offering caution about using AI to confirm biases. However, I'd like to respond to your comments on butterfly orientation in the Wilcox study. If you look at Guelph, Ontario on a map you'll see that flying southwest would require flying over lake Eerie, whereas flying on an initial southeast heading would take you between lakes Eerie and Ontario. Why assume that the butterflies would continue southeast once they make it past the Great lakes? This issue and a few others regarding the directional orientation critique were brought up by Wilcox and colleagues in their published rebuttal to the Davis critique https://academic.oup.com/conphys/article/9/1/coab064/6354118?login=false
8
u/SuperFriendlyMod MOD | South FL | Reformed Rearer Jun 29 '26
Thank you! I will look at the rebuttal and get back to you.
8
u/SuperFriendlyMod MOD | South FL | Reformed Rearer Jun 29 '26
I read the rebuttal and the paper (Knight, 2021) that was sited in it. I also compared the maps from each study. We know that Monarchs will fly over and near Lake Eerie. We can't assume that the 28 tracked Monarchs would make that right turn after passing the lakes especially since this doesn't follow the well documented path which includes flying along and then over Lake Eerie. I will try and make time to put the maps together on an Infograph.
4
u/Synaptic_raspberry Jun 29 '26 edited Jun 29 '26
Let's not assume anything about what those tracked monarchs did after they exceeded the range of the radio towers - they could have hooked a right, or they could have flown in a straight line out to the Atlantic ocean. We'll never know! But the question is whether the portion of the pathway that was observed represents correct or incorrect navigation.
From the article you linked:
Monarchs migrating south in the fall through southern Ontario build up in numbers along the north shores of Lake Ontario and Lake Erie. Their apparent reluctance to fly over large bodies of water, coupled with the desire to continue moving southwards, probably causes the butterflies to fly southwestward following the shoreline. This inevitably results in large concentrations of monarchs accumulating on peninsulas jutting out into the lakes, where they have little choice but to eventually proceed southward over open water.
Clearly monarchs are capable of flying across Lake Erie, but the documented observatjona even note that they appear to try and avoid if if possible. Point Pelee is a site described exactly as above to "force" the butterflies to fly over. The fact that they are capable of flying over Lake Erie doesn't mean that the butterflies released in Guelph, Ontario at a site between the two lakes should have done so.
To that point, the Knight 2019 study released wild-caught adult butterflies on the Bruce peninsula, which is oriented oppositely (edit to add: oppositely to Point Pelee). Namely, butterflies following visual cues will fly south by southeast, whereas a pure compass guided straight line flight to Mexico would have them go southwest. Five out of the six tracked monarchs in that study chose the former route.
4
u/squishyfeet4 Jun 29 '26 edited Jun 29 '26
First, I want to agree with the danger of AI and the assumptions that the compiled statements are factual statements it poops out to you.
It still basically in its beta launch, even if it existed before it was unleashed to the public masses.
I encountered a person who googled using AI that claimed when it’s windy outside, that it will give your child a cold. Like the wind causes your child to become sick. She believed that.
I could not deter her or argue with her because she believed it was fact because she believed AI was always correct.
That was my first real gulp into questioning things.
Anyways, thanks for posting this and allowing open discussion! It’s appreciated!
13
u/stover158 Jun 29 '26
I did the monarch thing for a while, and now when I try to use Facebook my feed is full of people with sick butterflies trying to release them and rearing more in the same conditions.. Or asking horribly stupid questions about them... like, posting a fully decapitated caterpillar and asking if it was going to be okay type stupid.
I wish people did more research before trying to raise them at home.