A few days back I was walking in a local favorite creek and became aware of a strong buzzing sound coming from the opposite bank. I made my way over and noticed a horsefly with its head stuck in the clay. I didn't know what to make of this at first...surely a horsefly didn't just fly smack-dab into the bank so hard that it drove itself into the mud. I gently reached down and took it by a wing and gave it a slight tug. I was instantly shocked to discover that there was a DINER with a very formidable set of JAWS attached to this most unfortunate fly. I had only a second to realize this because almost immediately the eater released its grip on the eatee and retreated with an amazing swiftness into a burrow previously hidden by the fly's body. I crouched there, staring at the now empty hole in the bank and the half-decapitated fly in one hand, and began to think. Then I noticed the other holes, hundreds of them. All perfectly round, mostly smaller than a pencil. To my amazement, I also began noticing the carcasses lying around in the mud near them....horsefly carcasses. While squatting there hardly moving, just quietly looking at the details of this strange new mystery, I caught a faint flickering motion among this colony of holes. I stared at one particular hole just as something moved within it and got another surprise. In that instant, an object rose to the entrance of the burrow, appeared to take a quick glance outside, and then just as quickly darted back inside and disappeared from view. This was happening all across the colony of holes. The very second I turned my head ar shifted even a bit, the activity stopped. They could see me. After 15 seconds or so of total stillness, they began having a look again, and then gradually satisfied that all threat had passed, these creatures would stay at the entrance to their holes, in wait, I guess, for the next unlucky insect. WHen they stayed at the entrance, they completely blended in with the surrounding mud and even up close I could not be sure of what I was seeing. It had to be the head of something but what? When I tried to get closer this resulted in every one of them darting back into the depths of their holes and the whole waiting process having to be repeated. There is no wonder that I never noticed their existence before--they would have seen the motion of my passing form and vanished long before I would have seen them....if not for that one horsefly! I finally decided that I had to dig one out somehow to get a better look at it, so I hunted up a bit of broken glass and assumed the position. I finally got one to hold still long enough and as quickly as possible drove the glass into the clay behind it. I doubted I would be nearly fast enough but to my surprise it worked and out popped the creature. It was NOT what I expected.
Here is a description of this insect, and all I can guess is that it might be the larval stage of some beetle , perhaps aquatic.
Roughly grub-worm like appearance, though not nearly as stocky or glossy and only covered with short, sparse, but readily-visible hairs.
The specimen I caught was possibly an inch long, a dusty cream color with a head the same color as the surrounding clay, probably from burrowing.
It had a narrow body, with six legs, all just behind the head as in grubs. I could not make out the details of the head to much satisfaction...another trip back to the site might be worth it to bring one home.
There was a strange dorsal "hinge-like" feature towards the rear. Just guessing but this may aid in scuttling back into the burrow so quickly (?)
It had very formidable jaws, which made an audible 'pop' when making an attempt on prey. Luckily it did not try to use these as a self-defense with me....
While in the hand it thrashed wildly and was able to throw itself into the air, similar to some young stages of caterpillar when caught.

There were hundreds of these holes grouped together, all situated on vertical banks above the waterline. The highest hole was less than two and a half feet up from the water.
This creek is a fairly "healthy" creek in that there is little pollution or channelisation and the water quality is usually quite good with an abundance of aquatic life. Average depth ranges from mere inches to occasional pools of under 5 feet and the substrate ranges from clay potholes to moderate cobble to sandy silt depending on what reach you are in.

I tried googling and yahooing this in all kinds of combinations..."carnivorous tunneling beetle larvae", "carnivorous tunneling insects", ...etc. etc. with no luck whatsoever. Probably one last bunch of words that I should have tried, but I thought the forums would be the best bet.

Can anyone help me????