These caterpillars were the last two of 2024. The one at left was easily, hands down, the largest caterpillar I have encountered, and he did something none had done before. He ripped open this pod from a syriaca plant and ate the skin hungrily, as if he couldn't get enough of it. He (after he eclosed later, I saw he was a male) ate and ate, refusing to leave that pod or eat anything else, although I made sure there were always plenty of fresh leaves in the enclosure. After awhile, the other one left its leaf and went over to him, climbed onto the pod, and did the same thing, whether in imitation or instinct, I don't know. Were they also eating the fiber? It did look like it and the fiber began to look frazzled and stringy, like it had been picked at quite a bit. The two of them completely denuded that syriaca pod before morphing into chrysalis. The second caterpillar was quite a bit smaller than the first one. Because pods don't develop until late in the season, would all larva prefer these over leaves if they were available earlier? Why did these two prefer this pod skin over fresh leaves? I have noticed that over time, a caterpillar will shift its food preference; for example, a caterpillar will eat only tuberosa leaves, but as it matures, it eats only syriaca; also sometimes a caterpillar strongly prefers tuberosa flowers.
According to a study by Michelle D. Prysby ('Natural Enemies and Survival of Monarch Eggs and Larvae' in The Monarch Butterfly by KS Oberhauser and Michelle Solensky, published by Cornell University 2004), ants are a voracious predator of Monarch eggs. Quote: "Of the 8 monarch eggs attached to milkweed ramets with F montana (ants) present, ants removed all 8 within 90 minutes..." I wonder if there is any way to reduce the number of ants on my syriaca. In my yard, the ants are all over the syriaca. The first year, I don't think ants had discovered the milkweed yet, and I was able to collect a good number of eggs. The second year, however, there were a lot of ants and I found only a few eggs; most of my eggs that year came from the tuberosa. The third year, I didn't find a single egg on the syriaca, which puzzled me; where were the eggs? I didn't connect this to the presence of ants at the time, as there were a lot of other creatures on the milkweed as well, such as oleander aphids, spiders, and of course milkweed bugs. But granted, ants were all over the milkweed. I would like to find a way to reduce the number of ants without harming them or any of the other creatures.
	What makes a caterpillar hang bent-out and sustain that posture for several hours? Can caterpillars get a "stomach ache?"
Do caterpillars and butterflies have "personalities," as we think of personalities? If not, how do we account for their behavioral differences, as in an active butterfly vs. a passive butterfly, one who seems to be aggressive and eager to leave the enclosure vs. one who "cowers" at the back of the enclosure and won't leave?
	Do smaller butterflies fare better in migration than larger ones? There is an assumption that larger butterflies fare better in migration, but at least one study came up with data that conflicts with this assumption. "....If the effect is real, it would suggest that smaller individuals are better able to make the migratory flight, contrary to previous suggestions that larger individuals are more successful migrants." ("Characteristics of Fall Migratory Monarch Butterflies in Minnesota and Texas" by Borland, Johnson, Crumpton, Thomas, Altizer, and Oberhauser, in The Monarch Butterfly by Oberhauser and Solensky, 2004, Cornell University.)
And finally, the Big Question. It is estimated that well over 90% of Monarch eggs and caterpillars in the wild are killed or eaten by predators. Some estimates are as high as 98% - 99%. By the law of the jungle, survival of the fittest, these were not "meant" to survive; nature weeds out the weak ones and they are needed as food for other forms of life. But what kills them and when? In at least one experiment, F. montana (ants) found and ate 100% of Monarch eggs within the first 90 minutes. In the wild, a few might escape the ants. But does survival of the fittest actually come into play at this point? For example, placement of the eggs? Every egg I have ever found in my milkweed patches have been on the under side of a milkweed leaf. I have not found any anywhere else. The question now is: Is it even possible that the eggs that were eaten by predators were somehow the weak ones, "meant" to not survive? How can an egg determine its own fate? How can there be a "strong" egg or a "weak" egg? A well-hidden or well-placed egg that allows it to somehow hide from predators? As the experiment with ants, referenced above, shows, Monarch eggs are predated on 100% when F. montana is present. It seems unlikely that this has anything to do with the strength or weakness of the egg. It could be that very small caterpillars bring into the equation the survival of the fittest, by being able to hide or evade predators, but it is unlikely this is true of eggs. If I bring eggs into a safe environment, how would this be allowing weaker, "less fit" butterflies to be released into the population as a whole? Obviously, more data is needed. My data show that in 2023, 91% of my backyard-raised eggs and caterpillars morphed into butterflies and were released. In 2024, the percentage of survived-and-released was at 76%.

     Contact: MonarchsMidwest@gmail.com  Thoughts and comments are welcome.