Rowly, can't say for sure without seeing them but we have a similar grub here in Minnesota. I had some in my fish which caused some conern. I checked with our state DNR and here's the scoop. I can't quote what kind of parasite this is but it's life cycle involves a period where it matures inside the gut of blue herons, then it drops into the pond with the bird feces, it is then picked up by snails, when a fish eats the snails it gets in the fish. It then somehow migrates into the fish meat usually just under the skin. After it matures it comes out of the fish and eventually gets picked up by the next heron. My DNR guy said since you can't get rid of snails you need to get rid of the Herons and your problem is gone. I began deterring Herons and since then I haven't seen a parasite. You might be glad to know that they are not harmful to eat since they can't infest a person but you should make sure they are cooked. Great news huh?

Gotta get back to fishin!