I am not sure but wanted to chime in anyways. I had something similar happen when I first started keeping reptiles I had this idea of buying a lot of crickets at one time and always having them on-hand. Well I put them all in a 10 gallon tank with peat-moss as a substrate (can not remember why I did that but I noticed the crickets putting their rear-ends in the peat-moss but I thought nothing of it. A while latter (after my crickets were gone) there was a ton of pin heads. I have wondered how fast they grow and if it would be worth it to raise them.