I bought some mealworms and tiny crickets for the chicks today. The guy at the store told me that I had to cut the heads off the mealworms or they would burrow into the chicks.....is this true? The chicks are 4 days old. Also, they only had grit with calcium so I did not buy it. Will they be ok until Wednesday when I can get to the feed store, or should I not give them these delicious treats?