Fruit flies stay very small. That small size plus how easy they are to keep and breed cheaply are what makes them a good choice to include in the diet of a small young chameleon

There are two common types of fruit flies - flightless and wingless. The flightless ones are a bit larger - black with red eyes. The wingless ones are a bit smaller, brownish in colour.
If your chameleon is less than 5 months old, feed it as much as it can eat within about 5 minutes, several times daily.
Lightly dust fruit flies with a phosphorous and vitamin free calcium supplement most daily feedings (some people dust only about half of what is offered). Dust with a vitamin powder about once a week - depends on the brand as to how often to use it.
Other prey choices for a young veiled would be small terrestrial isopods, small crickets, baby superworms, small butterworms, small/baby silkworms, leaf rollers, cockroach nymphs, grain moths, solider fly maggots (aka phoenix worms) and a limited number of small mealworms.