How do the Caddisfly larva do that?
Or a better question is .. Why do they do that??! WELL!!! the caddisfly is a very unique insect. It is the only aquatic insect that builds its own protective case out of the substrate that is in their environment.
The species that I collect is pynchopsyche gentilus. They are found in headwater streams throughout the appalachian mountains. What is really crazy about these caddisflies is that they first build a "pre-case" that is made of leaves. The young larva will start building a protecive case using cutouts from leaves. The larva will cut round circles of leaf material out of the leaves and glue them togher. The glue is a silk that the caddisfly larva produce and use as their "glue" to secure the pieces of leaves or stones together.
So, the caddisfly larva has a one year life cycle. The larva hatch from egg masses in the fall. When they emerge from the case as a little larva, they immediatly begin to build a protetive case around them. This is when they are building with the leaves. As the larva grows in its "instar" stages, it will build a larger case. When the larva is in a leaf case that is about 1" in length, it is then ready to transition into its stone case. This happens at about Mid March. The caddisfly will then start adding stones to its leaf case. As the stones are added to the leaf case, the caddisfy larva moves into its stone cases and leaves the leaf case to be used as food for itself or for other caddisflies to eat. Oh, yea, the main food for the caddisfly is leaves. They are very important to the stream ecosystem because they do eat the leaves in the stream and break down the bacteria and algi that grow on the leaves.
Now, as the caddisfly larva is building its stone case, it takes its time because this is the final case and also the cacoon that the caddislfy larva will use when it is ready to go into metamorphosis and change into the adult form of the caddisfly.
The species that I collect is pynchopsyche gentilus. They are found in headwater streams throughout the appalachian mountains. What is really crazy about these caddisflies is that they first build a "pre-case" that is made of leaves. The young larva will start building a protecive case using cutouts from leaves. The larva will cut round circles of leaf material out of the leaves and glue them togher. The glue is a silk that the caddisfly larva produce and use as their "glue" to secure the pieces of leaves or stones together.
So, the caddisfly larva has a one year life cycle. The larva hatch from egg masses in the fall. When they emerge from the case as a little larva, they immediatly begin to build a protetive case around them. This is when they are building with the leaves. As the larva grows in its "instar" stages, it will build a larger case. When the larva is in a leaf case that is about 1" in length, it is then ready to transition into its stone case. This happens at about Mid March. The caddisfly will then start adding stones to its leaf case. As the stones are added to the leaf case, the caddisfy larva moves into its stone cases and leaves the leaf case to be used as food for itself or for other caddisflies to eat. Oh, yea, the main food for the caddisfly is leaves. They are very important to the stream ecosystem because they do eat the leaves in the stream and break down the bacteria and algi that grow on the leaves.
Now, as the caddisfly larva is building its stone case, it takes its time because this is the final case and also the cacoon that the caddislfy larva will use when it is ready to go into metamorphosis and change into the adult form of the caddisfly.