I found this info about hornworms on www.mulberryfarms.com, thought I would share it.
Goliath worms grow so quickly sometimes they grow too big, too fast for some customers animals to eat. When Goliath worms reach the size desired - you can slow growth dramatically and extend shelf life considerably (by a couple weeks) - if you store them between 55 and 65 degrees.
DO NOT REFRIGERATE them because most refrigerators are between 35 and 40 degrees (too cold) which will usually kill them. The easiest way to extend their shelf life is to place the worm cups in an ice chest with small blue ice packets and exchange the blue ice with fresh ones at least once or twice a day to keep cool.
There is enough food in each cup to raise several worms to full size. If however you run short on food, they may become cannibalistic. Larger worms can eat bell pepper or you can purchase additional Hornworm food from Mulberry Farms at www.MulberryFarms.com.
CAUTION: DO NOT FEED TOMATO OR TOBACCO LEAVES TO HORNWORMS BECAUSE THEY ARE TOXIC TO REPTILES!!!