As your dragon is 18 months, I would only feed a few insects a day (about half dozen) and deffinitely salad. Adult dragons don't need alot of protein once they are full grown. Gravid females do need more protein but other than that, a few insects a day or a couple normal insect feedings a week, is more than enough. A variety of insects deffinitely is great as well. Just remember that adult dragons only need about 10% of their daily diet as insects, the rest should be greens.
I suggest cutting out the waxworms altogether, offering them maybe once a month or less. Silkworms, butterworms, roaches, etc are great to feed as well. You can feed locusts much as you feed any other insect, just remove the large hind legs on adult locusts, as these may damage the dragon's mouth or throat because of the sharp spurs.
The waxworm/superworm/mealworm beetles are fine to feed, but in moderation. They do have a hard shell and if too many are fed (ie say a dozen at a sitting) may cause impaction. The moths are fine, they can be fed freely. Silkworm moths are great as well.
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PHLdyPayne