Surprise isopod family

[Synapze]

I brought in a moss specimen for one of my terrariums a few weeks ago and apparently it had a isopod hitchhiker. It's been wandering around eating old debris in the substrate and seems to be very active. Now, it appears there are 4... all are approximately 1/8th inch long. I don't know if they were just really well hidden in the moss specimen and finally decided to show themselves today... or if there has been some reproduction, which I really doubt... but I know practically nothing about isopods, which I assume these are. 

Question: Since this terrarium doesn't contain any other animal life, and from what I've read isopods eat decaying plant matter and waste, will the natural breakdown of the home mixed substrate be enough to support them or should I throw in some mantid poop or small dead insect scraps from time to time? I don't want to place any addition substrate (dead leaves, etc.) since the terrarium was designed for decorative use. I haven't noticed if they've been eating any  of the live moss specimens... I hope not.

 

[Cole 78]

I would add some mantid waste and scraps of dead insects. Some decaying plant matter would help as well. 

 

[ohaple]

Much of their diet will be decaying wood and leaves. If you want to supplement their food, you can do so using fish food. They don't eat much, especially if you only have 4.

I have my dwarf white culture and giant canyon both set up to use a good substrate with bark, leaves, moss, peat, etc. Then I put a piece of mood moss on top. I mist once or twice a week, and feed a tiny bit of zuchhini or fish food once or twice a week.

I am terrible at ID'ng isopods, but my guess with you being in the US is that this is a young armadillidium vulgare. They are very common and often have a pattern like that. Based on the size I was going to guess dwarf purple, which are common in the reptile trade, but they have a flatter look and different coloration.

You will likely be able to find more outside depending on where you live if you want to start off your culture a little stronger. Most people advise never to put "outside" isopods directly into mantis or reptile enclosures since they can carry pests. Instead, wait for them to breed and then put the babies in.