The egg hatched and then the larva began tunneling inside the leaf. You can see that as the larva tunneled and ate, it grew, as might be expected. Finally you can barely see where the larva metamorphosed and ate its way out of the leaf, leaving a tiny hole. Leaf miner squiggles occur in many kinds of leaves, and usually a species of leaf miner patronizes a certain species of plant leaf. Such squiggles are extremely common, so finding your leaf miner tunnels could be the goal of an interesting fieldtrip.
Some pupae develop inside cocoons , as in the case of bagworms .
A bagworm cocoon is shown at the right. Bagworm adults are small, stout-bodied moths, of the family Psychidae . Psychid larval bags, like the one at the right, are portable. Sometimes you can spot a bag slowly creeping along a stem. The bagworm cocoon in the picture was found on a twig of Loblolly Pine and if you look closely you can see that some pieces pine needles have been incorporated into the bag.