We recently heard from one of our young readers, whose aunt wrote to us on his behalf (he is 5 years old). He would like to know how to tell the difference between a “worm seed” and a regular stone. He is also curious if “worm seeds” are soft or hard. His aunt made a note that by “worm seed” he means cocoon. We are more than happy to provide some answers for our curious reader!
We will start by explaining the lifecycle of a butterfly. (It should be noted that a moth experiences the same stages as a butterfly during its lifecycle, but for simplicity’s sake we will just use the word butterfly.) An adult female butterfly lays her eggs on the plant of her choice. This isn’t any random plant, but the plant that will serve as a food source for her babies, known as the host plant.
After about a week (or sometimes longer or shorter depending on the species), an egg hatches and a larva emerges. The larvae of both butterflies and moths are commonly referred to as caterpillars. The larva, or caterpillar, then begins to eat the host plant. In fact, all it does for the next 2-4 weeks is eat, shedding its skin as it grows bigger and bigger. Once the caterpillar is fully grown, it is ready to transform itself into a pupa, which is the transformation stage between the larva and adult. (The term pupa can refer to both butterflies and moths, the term chrysalis is strictly used for butterfly pupa.) To undergo this transformation, the caterpillar spins a silk cocoon and hangs upside down in a J-position. Inside, the caterpillar breaks down and reforms itself as a butterfly! This process takes about 10-15 days. Finally the adult butterfly emerges from its cocoon! Later, adult butterflies mate, females lay their eggs, and the cycle begins again!
Now we will address our reader’s question. He used the word “worm seed” and his aunt clarified that he meant “cocoon”, but what exactly is it? Well, while a pupa or chrysalis is the actual organism, the cocoon is just the silk casing that covers and protects the organism during its transition. So, how is a cocoon different from a rock? Well, the answer to that is a little more confusing because not all cocoons are the same. All contain a caterpillar transforming into a butterfly or moth, but not all look or feel the same. While some cocoons are soft and web-like, others are hard and solid. Some are almost translucent, while some are solidly colored. Most caterpillars choose a secluded and safe place to spin their cocoon, like the underside of a leaf or under a small branch. Unfortunately some cocoons do fall onto the ground, where it could be mistaken for a rock. However, most cocoons are shaped like a bean or teardrop and aren’t as dense as a rock.
Although we weren’t exactly able to provide a straight forward answer for our reader, we hope he learned something interesting from this article! If he wants to witness the process of a butterfly emerging from a cocoon, he should ask his aunt to take him to a local butterfly house or butterfly pavilion. To find the nearest one, she can do an Internet search for “butterfly house [town, city, or state]”. Depending on which state he lives in, there might be 1-2 to choose from!