Preheat oven according to directions on the crescent-roll package. Prepare the sausages according to the directions on the package. Use tongs to remove the cooked sausages from the frying pan and place them on paper towels. Allow to cool ten to fifteen minutes. Cut the sausages in half lengthwise. Then use the rounded tip of a carrot peeler to scoop out a long, shallow trough down the length of each half. Squeeze a thin line of mustard into each trough.
Separate the crescent-roll dough into its pre-cut triangle pieces, and lay them flat on an ungreased cookie sheet. To form insect larvae, take two sausage halves and, with their mustard-filled sides touching, put them together to form a whole. Place a whole larva at the wide end of each dough triangle, and roll up dough as you would regular crescent rolls. Pinch the ends and seams of the rolls closed. Bake according to package instructions.