Here is what makes the ‘bag worm’ cocoons that people often spot on evergreens 🌲. Bag worms are a moth caterpillar 🐛. Look at the little legs 🦵!!! The males moths will eventually form and fly away from the cocoon, but females simply stay put and release pheromones 👃 to attract suitors. The female will end up laying eggs 🥚 in the cocoon, which also becomes her tomb 😕. The eggs will survive cold weather 🧊and the cycle will continue the following year when caterpillars hatch in the spring 🌺