Studies have been conducted to determine whether the adult butterfly remembers from the time it was a caterpillar. Sure enough, once the studies were concluded, there was scientific fact that they do so. Studies like this are great, providing scientific proof of many things.
We never think of things like this because we assume it would already be known. After all, the caterpillar is only the young/child form of an adult butterfly. The ‘brain’ (ganglea) stays the ‘brain’ from caterpillar through chrysalis into the adult.

We had been raising plantain (Plantago lanceolata) for a couple of years before we started to raise Buckeye butterflies. Because their host plant that they use in the fall has tiny leaves that dehydrate almost immediately, even when placed in water, we were desperate to find another host plant. Reading a bit in a couple of books, we read that they also host on the same plant we were growing as an herb at our herb nursery. We placed few large full-leafed plants with caterpillars. The next morning, the leaves were completely devoured, down to and below the soil level. We released quite a few of the adult butterflies when they emerged. Before long, our plantain, growing in pots for customers, were tiny instead of as large as they had been. They were covered in Buckeye caterpillars. Although thousands of Buckeyes migrate through every spring and fall, they had never laid eggs on our plantain before we raised caterpillars on it. Once we fed caterpillars plantain and released the resulting adults, they laid eggs all over the plantain. After the initial surprise to see the plants, which had never been eaten, suddenly covered in hundreds of caterpillars, we realized it made perfect sense. The butterfly with wings is nothing more than the caterpillar all ‘grown up’.

We learned that raising caterpillars on a less-favored yet totally legitimate host plant is a good way to start a generation that will, for the most part, prefer that plant when they lay eggs.
There are so many topics that are still waiting to be studied in proper scientific studies. Done properly, any of us could do these studies and write up a paper on our experiments and results.
What have you learned that you later realized was new information to butterfly and moth enthusiasts, citizen scientists, and/or lepidopterists?