Lightening bugs are deadly to a dragon and earthworm contain something that can cause them to get very ill.
Since dragons have not been in captivity that long, it has been more a thing of what CAN we feed them and KNOW it is safe. crickets , silkworms, hornhowms, mealworms, roaches, superworms, Waxworms (limited amount, a lot of fat), a few other I have seen on here but not used.
You can use baby food in a pinch, chicken, turkey and the vegetables and there is also a can pet food supplement you can get from a vet called AD that is also safe to give them for a short time... this is an excellent source for a sick dragon or one on treatments that is not eating much.
Pellets are another option when you do not have crickets on hand, make sure you moisten them and the ones that dragons eat best is Rep-Cal.
Melissa Kaplin has a page that list toxic plants to avoid and you might want to check that out on the link below
Melissa Kaplin's website-toxic plants