Haha Bill@ Yeah I put some egg shells in with them occasionally, but not to often. Do they actually eat the shells? I sorted the ones out I could into a smaller breeding bin and put it next to my 2 springtail bins. I had totally forgotten about these and wrote them off as dead. I am so thrilled they survived and from what I say the black bug infestation is over. I put a leaf and some yeast in the tank to see if any springs made it, but I am not hurting on those. I am actually thinking I may need a 3rd Spring culture soon. Those suckers are prolific breeders lol.