Bearded Dragons and Fruit flies

Question
How do I go about feeding my BD's fruit flies? When I let them out in the Vivarium they just fly to the top of the walls and my BD's cant seem to reach them. They are very active and enjoy crickes and plenty of veggies.  My BS's are about 3 months old and have grown alot in just 2 weeks since I've had them.  Lilly and George seem to be very happy, however they do seem to face up to each other now and then and I'm wondering if Lilly may be a George afterall!!

Answer
 Fruit flies are not usual beardie prey, but try putting the container in the fridge to slow them down.  Also get phoenix worms as a nutritious bug for babies, also silkworms, hornworms, and, of course, crickets that are appropriately sized.
 You may be able to tell male from female at this age.  Hold the beardie with his tummy resting on your hand with the tail facing you.  With your other hand lift his tail straight up and look above the vent. If you notice two little bulges side by side with a dimple in between, he's a boy, If there only one little bulge smack in the middle, it's a girl.
 I would start thinking of setting up a second habitat in a month or two, if not sooner if they are facing off.  Beardies are very territorial and should each have their own space.