My chicks are 4 weeks old today. I have not given them any treats--they eat only the starter crumbles. However, I moved them out to the coop today and I noticed that there are bugs in the coop (i.e. ants, spiders, a roach). If my chicks were to eat these bugs, do they need grit?? Now I'm panicking because I don't have grit and I don't want my chicks to eat these bugs if they need grit. Please advise. Also, if I do need to give them grit, where do I get it? Is there a certain size grit I need?