Try mixing up his feeders also. One day silks the next day crix and then hornworms. If you can get some horns that are small enough for him thats what i would try next. My panther really started growing when i started adding a wider variety of feeders at around the 3 month mark. Good Luck fattening him up. Btw since he's a veiled try adding some greens and some fruit to his diet also. Strwberry and mango are great fruits to give them as are collard greens or kale.