Monarch caterpillars molt (shed their skin) five times throughout their larval stage. The "skin" that is left behind is actually the caterpillar's exoskeleton. An insect's skeleton is on the outside, as opposed to on the instead like mammals, fish, reptiles, amphibians and birds. Endoskeletons provide support inside the body in the form of bones and cartilage, whereas As caterpillars grow, their exoskeleton gets too tight, so they need to shed it in order to continue to grow. Each molt results in a new "instar" stage. Therefore, when the egg hatches, that tiny 2 mm caterpillar is in its first instar stage.
It will molt three more times and grow exponentially over a couple of weeks. Each stage lasts 3-5 days. The fifth and final molt is when the fifth instar caterpillar becomes a chrysalis.
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Knotweed Identification
Browse our knotweed slides below to learn how to identify these invasive plants before they take over your yard, park or garden. These plants (with the exception of Himalayan knotweed) are destructive, breaking apart asphalt and entering homes through the foundation. Check out the Knotweed! app to learn more about all four species of knotweed: Japanese, giant, Bohemian (the hybrid of Japanese and giant) and Himalayan (uncommon).
Note: Japanese knotweed is on the list of 100 top invasive species in the world.
