Phosphorous-free calcium dusted (at most feedings) on the insects before feeding them to the chameleon will help to make up for the poor calcium to phos. ratio found in many feeder insects.
The phos.-free calcium/D3 dust can be used lightly twice a month to ensure that the chameleon is getting enough without overdosing it. D3 from supplements can build up in the system...so don't overdo it.