The yellow thing is the adult female, which lacks legs and eyes. Basically just mouthparts and gonads. The cover, which you peeled off, is secreted for protection. The males are more insect-looking, have wings, and can fly.
The only way to reliably identify the adult female is to make a slide-mount of a cleared specimen so all the microscopic features can be seen. That's a lot of work, but some educated guesses can be made based upon the host, geographic range, and the shape/color of the cover.