The powder with a warm bath and several rinses and clean the cage thoroughly before reintroducing the specimen.
These two insect killers should be available through your pet dealer or veterinarian. A mixture of half-and-half castor oil and 90% grain alcohol brushed on the affected areas may also eliminate mites. Don’t dip your pet in this mixture; just apply a little locally. Note that 90% grain alcohol is not 90 proof. You can buy 90% grain neutral spirits in your pharmacy or liquor store. A little goes a long way.
If you pick off ticks and chiggers with the tweezers, you might well follow up with an alcohol swab to help reduce the risk of infection at the sore spot. Perhaps a pretreatment with the alcohol will tend to loosen the tick before you attempt to pick it off. This passage is not intended to scare anyone from keeping an iguana. People have had dogs and cats with chiggers, ticks, mites and fleas for all of the recorded history.
A number of large and small ticks attached under the edges of the scales of a rainbow boa. The ticks found on iguanas are usually similar in appearance to those found on snakes – ticks are not too choosy.