I have a ton of them that hang out in cool, moist places near my rose bed. While they tend to give me the creeps a bit, I haven't found that they have done any harm so I leave them be. As Karl mentioned, I think they primarily feast on dead or decaying plant material.

I have a transplanted "lamb ears"(stachys byzantina) I went to check on it, its doing well- as I was pulling some dead leaves, the base had a deep hole-It spooked me, didnt want my hand bit by something, then I saw a whole bunch of rolly polly bugs-I hear they eat dead leaves-so, are they doing good for my plant, or are they killing it??? The amount of them creeps me out...

Funny but I didnt think they ate anything at all until I planted strawberries and then POW! They do love themselves some strawberries...Oh and by the way, baby pigeons and birds like to eat these, we get lots of baby pigeons roaming and waddling around the backyard looking for food. I started the strawberries from root bunch so they didnt eat them, they waited for the berries. Just when I think I get a nice berry, there they are underneath munching away. I just spray them off and eats what left. They are very clean, I will give them that. Interesting thing I just actually learned tonight...I was looking for something I dropped earlier out in the backyard, so I went out there with a flash light. As I began looking in the grass (which is about 20 feet by 60 feet), I noticed tiny little black bugs everywhere and I mean EVERYWHERE, they turned out to be rollie pollies. Some wear eating the dead grass, some were eating the tips of grass, some were just laying around, some were sleeping in bunches, others were "wrestling". I couldnt believe how many, possibly thousands. Tens of thousands. But yet I still have full strawberries if I find them before the bugs...They wait for them to get ripe BTW but when the berries get scarce, they begin to eat them when they are yellow. But they leave the actual plants alone. And I just finished planting a buttload of butterfly plant/weed seeds too. Which just happens to be their favorite. Pillbugs are not bugs, they are crustaceans, much like shrimp and crayfish. Pillbugs breathe through gills. Because of this, they need a lot of moisture or they will die. They cannot survive in water, but they must have water vapor in order to breathe. Pillbugs molt and shed, but they don't do it all at once. They shed half their exoskeleton and then shed the other half later. Pillbugs are like kangaroos because they carry their eggs in a pouch. The babies remain in the pouch for a few days and then move on. Pillbugs do not urinate. I found this fascinating because the thought of bugs urinating in the first place already seems weird and a little gross. Urine contains ammonia that must be excreted from the body, but pillbugs are able to deal with the ammonia gas and pass it straight to their exoskeleton. Pillbugs drink through their butts. They can drink through their mouths, but they also can take in water from the rear. Pillbugs eat their own poop. As if some of this information is not already alarming, pillbugs munch on poop and rotten veggies all day and even eat their own poop in order to recoup the lost copper in their bodies, which is needed in order for them to live. This is also known as coprography (or gross if you want a simpler term). Pillbugs have blue blood. The color is from a substance called hemocyanin which contains copper ions. When oxygen comes in contact with this substance, the blood of a pillbug becomes blue. Also when pillbugs get sick, they also turn blue. Pillbugs live up to two years and are active at night time.

If everyone tossed the tomatoes that had been snacked on by those insects, we'd never get to eat any! However, the soybean field would worry me.