the cool thing about getting the flies from the breeder is that you can make sure that your flies has not touch or eat nasty stuff.
I do agree with Trion that in the wild those things are probably don't matter..
But i would recommend to buy the culture anyway..
They will arrive in pupa stage.
You just put the pod in room temperature and by 2 or 3 days you'll see about 250 little flies buzzing around.
Put them in the refrigerator (lower one)- don't freeze them to death

to slow their metabolism. (i say about a day -flies start to die when you refrigerate them for more than 4 days).
Put a spoon of baby cereal+1 boiled egg+ Honey+ plain yogurt and blended them together to make a thick liquid baby food consistency..
I'm embarrassed to say that be4 feeding them to the flies, my curiosity get a hold of me...and yes... i did try a bit.. it actually taste good.
open the lid slowly after tapping some of the flies that climb on the side of the cup so they all fall down.
since you refrigerate the pod, the flies will be too weak to fly.
put a teaspoon of the gutload into the pod.
And from now on, you can put the pod in room temperature.
As soon as they wake up, they will start to feed.
Wait about 3 to 4 hours, they are ready to be your chameleon's delicacies.
Put the fly pod in the refrigerator again for about 15 minutes.
And prepare a clear plastic.
Open the pod, pour some unconscious fly into the plastic.
and then pour the fly into the screen cage.
and presto!!! your cham will definitely get excited and start hunting..
quite cool to see the cham hunt flies..
see from a far though just in case you have a shy chameleon.