Can My Bearded Dragon Eat Dead Insects?
All bearded dragons, regardless of age, need part of their diet to be live insects. Younger dragons need 80% live protein in their diet, while adults only need 20% live protein in their diet; your dragon will never stop needing to eat live bugs.
Dead insects do not have nearly as much nutritional value as live insects. When insects are alive, their bodies are mainly water, and this is what holds the vast majority of the nutrients in their bodies. When they die, they start to lose this water and the nutrients contained within it, so most of the nutritional value is lost. Also, bearded dragons love to hunt. It's an excellent form of exercise and stimulation for them, and they will lose the need to hunt their food if they don't have to anymore. This leads to them becoming lazy and always expecting to be hand fed or just have the food set in front of them. When you try and feed them live insects again, they may not even try to hunt anymore and just let them get away.
You also have to consider why the insect died in the first place and the fact that dead bodies attract bacteria. If the insect was sick or had parasites, then you could easily pass these on to your dragon when you feed it, and this could make your dragon extremely ill. The only safe way to feed dead insects is to purchase commercially prepared dried insects, but these are more meant as an emergency supplement in case you cannot obtain live food, and you do not want your dragon to go hungry. If you are scared to feed live insects, then you probably want to consider a reptile that doesn't need to eat live food rather than getting a bearded dragon as your pet.