Help identifying a possible root pest

[schmiggle]

I already posted this in the plant forum, but I figure I might have better luck here, given that this is an insect.

Sadly, the following picture is the best I could get:
It has a reddish-brown head and a gray-black body, it's about half an inch long, and bunches of them were living in a wet soil composed of fifty percent peat moss and fifty percent sand by volume. They burrow out of the soil when I add water, presumably because they begin to drown. I am concerned they may be feeding on my plant's roots.

 

[myrmecophile]

Looks like a millipede. Some can be a problem others not so much.

 

[Hisserdude]

Actually it's not a millipede, looks like a Lepidoptera larva, probably some sort of moth. Some can be serious plant pests, so I'd suggest posting pictures on Bugguide.net to see if any of the experts there can identify it further, though they'll probably need a clearer picture.

 

[myrmecophile]

Upon further examination of the image it does indeed appear to be a lep larva. But as mentioned a much better image is going to be needed for Id.

 

[schmiggle]

Thanks guys! Here are a bunch of better pictures (will post on bugguide as well). They still aren't great, but they are much clearer.

 

[Jacob Ma]

You can tell if your plant's roots are harmed by checking the coloration of the plant. If the leaves start to blotch or brown completely, then something is wrong with the root system. You can try checking the plant's roots as well, as eaten roots should appear black (unless if naturally black) and have evidence of minute bite marks. I don't think this caterpillar is a particular root pest, but rather a ground-dwelling species that must have tried to hibernate or smuggle itself into a warmer climate. Some species of ground-dwelling caterpillars will cluster or congregate with each other to have a sort of safety in numbers, and find food and shelter as one mass.

 

[The Snark]

A belated FYI. Saw several thousand grubs exactly like the ones pictured. It's a Scarabaeiformia.
The farmers around here have tricks to deal with them. They shade the street lights adjacent to their fields to keep from attracting the beetles. They also hang a light on a long bamboo pole over a pond so the beetles fall into it and drown (or become frog feasts). Then when a field is heavily infested they plant potatoes. The roots and fruit have a powerful poison, Solanine, that does a severe knock down to the grub population.