Chameleons are insectivorous and will do quite well with insects that you should be able to purchase from local pet stores. Most people feed their chameleons a regular diet of crickets, which can usually be bought from wherever you purchased your chameleon in varied sizes. However, if you live in an area where you cannot get insects regularly, they can be ordered online or by telephone and delivered to you in bulk.
It is good practice to try and feed your chameleon a varied diet of different types of insects. Some of the more common insects you should try and feed your chameleon are crickets, wax worms, meal worms, super worms, fruit flies (for younger chameleons), flies, moths, and grasshoppers. Be careful how many larger winged insects (such as moths) you feed your reptile as the wings can be difficult to digest, and this could lead to bigger problems. Also, be cautious with wild caught insects. Make sure they haven't been subjected to any types of pesticides since these would then be passed on to your chameleon an cause significant harm to it.
Make sure not to feed your chameleon insects that are too large for it. It should not have to gag the insect down. If you see that your chameleon is doing this, try using smaller feeder insects in order to prevent choking.
How much you will need to feed your chameleon will vary depending on several factors. Chameleons will usually eat much more when they are experiencing a growth period. Don't be surprised if your pet is consuming 15 or 20 large crickets a day during this time.
Temperature is another factor. If you find your chameleon is not eating much, you might want to try and increase the temperature of his/her enclosure for a few days. When chameleons are too cold, they will become more sedentary, and thus, burn fewer calories. This means that they will likely eat less since they do not require as much food energy.
The simplest way to figure out how much your chameleon needs to eat is to observe his/her eating habits closely, and feed him/her according to what he/she seems content with. Make sure to note and lengthy changes in eating habits which seem to arise for no apparent reason. There is usually no need for alarm, but be watchful all the same.
Gut loading is a tern used to describe the fattening-up of feeder insects with vitamin rich foods. Equally important as the insects you feed your chameleon, is what you feed your insects. It is important to note that if you are not feeding your insects a vitamin rich diet (or not feeding them at all in some cases) the nutritional value of them decreases significantly, and your chameleon ends up eating what is in essence, empty shells. Everything you feed your insects will inevitably be passed on to your chameleon, so feed them well.
A good diet for insects can consist of potatoes, carrots, cabbage, fish flake, low-fat kitten chow, bee-pollen, and potato flakes. Commercial (insect) food with concentrations of calcium and other essential vitamins are also available, but not a necessity. The bottom line is, feed your insects well.
Also, you will want to dust your insects with a calcium rich supplement before feeding them to your chameleon. You should try and find a cricket dust with a calcium/phosphorous ratio of 2:1 in favor of calcium.