Maggots are fly larvae. Flies land on the body, lay eggs, and the larvae feed until they hatch. Then the cycle repeats itself.
If a person dies in a hermetically sealed clean room, maggots would not appear unless the flay larvae were already there. If they died outside the room and were brought in, the eggs were already laid.
This actually makes sense to me now and I will explain why. I have dogs that do their business outside and within minutes you can see flys flying around the "poop". When I pick it up and place it in a bag, within days maggots appear.
When you think of it, while you are outside having a bar-be-que, those flies land on food all the time. Place that food in a bag in a car or trash maggots will appear.
I am not saying they were in the pizza, but I feel at some point flys landed on Caylee, like they would land on me while walking around and drop an egg. If Caylee was placed in the trunk at some point after she died, these maggots will appear for sure as well as hanging out on the pizza.
I also feel the Anthony's dispose of their dog and cat waste in the trash, which will also bring on the maggots.
I still rule out the pizza theory!