Does a bearded dragon need to eat live insects?

As a baby/juvenile, bearded dragons should be eating mostly insects with leafy greens (for example collard greens, dandelion leaves etc.) in roughly a 70%-30% proportion in favour of insects. Stick with crickets as the main staple diet, and provide locusts (if you can buy them in your country) as a treat. Avoid mealworms until they are a bit older, but still don't offer them as a staple when they're older, only as a bit of a treat. The rule of thumb is that the food should be no bigger than the distance between the beardies' eyes. The reason for avoiding the mealworms at an early age is because they provide insufficient nutritional value, as well as risking impaction within your beardie because it cannot digest the crunchy outer shell.

The insects should be live as it provides better nutrients and more protein for the dragon, as well as providing exercise while it hunts the live food. Also remember to not capture your own insects as these may have come into contact with pesticides whihc may harm your dragon. Also remember to dust the insects with calcium (which helps the beardies bones, as well as helping to absorb vitamin D from the UVB light within the enclosure). As well as dusting with calcium, once every few days you should add some powdered multi-vitamins to the insects too, which should keep them healthy.

As beardies get older they become lazier. This is normal and can be witnessed even before the sub-adult stage. When the dragon gets older, the percentage of food given should be, more or less, reversed (i.e. provide 70% greens with 30% insects). Just like always the dragon should be provided with a food bowl filled with salad each day, but expect to have to refill it throughout the day as it gets older. Fruit may also be offered, but avoid citrus fruits such as lemon and lime. Live insects should be offered every other day, as opposed to the daily routine in it's youth.

Hope I helped. :)