this can be a common problem for any xanth raised on primarily one feeder, it often takes them quite a while to become accepting of feeders other than what they are accustomed to (with the exception of cultured flies or cultured small brown garden snails.
cricks are a poor feeder, they are too exo-skeletal and too high in phosphorous. imo, he should be eating a diet of (non vitamin enhanced) gutloaded dubia, cultured blue or green bottle flies, silkworms, bsfl and the occasional cultured small brown garden snail. and only occasional treats of things like, waxworms, meal/superworms etc. i recommend reserving cricks mostly for dusting/supp purposes.
cham metabolic and nutrition issues are very complicated, and phosphorous plays a very important role in all of it. imo, you are better off relying on more of a healthy diet and less on supplemental additives. not all items you might think are healthy are a good choice. for outstanding info on cham nutrition and balancing cham healthy foods visit sandrachameleons outstanding blog;
https://www.chameleonforums.com/blogs/sandrachameleon/nutritional-information/
http://www.uvma.org/chameleon/vitamind3.htm
http://www.newmanveterinary.com/kidney.html
your comment "waive a worm at him" implies hand feeding, something that many xanths never become comfortable with, especially if not discreetly and patiently introduced to it. going without food for several days at time is no prob and actually good for them, it allows their digestion and nutrition to catch up on any still in process issues.
imo, i would give him several days without food and use the time to order blue bottle fly spikes from mantisplace.com. blue bottle flies are one of a xanths favorite feeders. after a week or so without food you could introduce a dozen or so daily bbfs into his cage via a controlled release container. if that doesnt make him forget about cricks for a while, i would say there are likely other issues brewing. jmo
ps blue bottle flies are easy to raise and keep going, just repost or pm if you need help with them.
also, was this a hornworm you were waving? if so, best to feed only smaller ones or break the mandibles on the larger ones.
