Step I - III
The chameleon notice a movement. the prey is then located and determined as edible. During this step, chameleon calculates the exact position of the prey for accuracy.
II. "Localization" (see picture box #1 and 2 by Robert Salas below)
The chameleon focus both of its eyes and move slowly to close the distance between him and the prey. And, he moves slightly forward.
III. "Protrusion" (see picture box #2 and 3 by Robert Salas below)
This signified by the chameleon opening his mouth and protruding his tongue slightly. A sign that he is ready to shoot at any moment.
Step IV "Projection" (see box #1 by Paul Kartsub below)
When the chameleon is ready, its tongue will immediately be shot at a high speed toward the prey. Usually, chameleons instinctively focus to shoot for the insect's head to minimize retaliation from the prey. Once catapulted, the chameleon cannot halt the tongue in the middle of action.
Step V "Retraction" (see box #2 and 3 by Kartsub below)
As the tip of the tongue become somewhat extended in width, the tongue is then pulled backward creating a vacuum/ suction motion (think of their tongue to somewhat similar to straw). On top of the muscle that able to hold the prey, the suction stabilizes the prey preventing them to be able to break loose easily. Contrary to popular beliefs, chameleon tongue (although somewhat sticky) are covered with moisturizing agent. So, they do not depends on the stickiness of their tongue as much as they depend on gripping and vacuuming.
Notice the bent tongue in the 3rd photo from the top by Kartsub. The bent area is the point where the Hyoid bone ends.
Step VI "Consumption" (see box #4 by Kartsub above and box #1 by Kartsub below).
During retraction, once the tongue is in close proximity to the mouth, the chameleon will close both of his eyes by reflex to avoid injuries from the struggling insects.
The next step is pretty obvious. The chameleon will bite hard to deliver a fatal blow to the prey .