They look like flesh fly larvae.

Agree that they look like flesh fly larvae although with nothing for scale to determine size I can't say for sure. But FF larvae don't normally bother living plants IME. They are basically carnivores and eat other soil dwelling larvae, carrion, manures, and some decaying soil matter.

What are the symptoms of "killing your plants"?

Dave

Japanese Beetle larvae pic

usually appear much larger than these do and are curved almost in half in a pronounced C shape.

Dave

Whatever they are, they seems like some sort of maggot. I think your soil is too wet and if you do not like them there, change it's environment. I would add something dry, like sand. It will probably kill the bugs, but be aware it might not do your plant any good either.

Put up a bird feeder and rake the top few inches of soil ever day. The birds attracted to the bird feeder will spot them after a raking and go to town. Garden will look like a mine field, but they will eat them up. Are they in just the few top inches of soil?

In the background of your picture, your garden bed appears level or close to it with the grass. Did you dig a bed and fill with soil? If your soil is clay, you probably created the Bathtub effect. You may need to create a raised bed to prevent the bathtub and waterlogged soil which is probably the culprit killing your plants, not the bug larvae. When you water, the clay doesn't allow the water to escape/drain, your plants roots are sitting in water and rotting. Raise the bed and backfill with more soil next year. Just a guess from a blurry picture.

Amelia, these little animals are not the larvae of any kind of beetle (called grubs) and they certainly are not slugs. They are maggots of some kind and their pupae, the darker ones.

Not killing your plants.

So please provide more information about the plants, their immediate environment, and their care.

Most similar pic I could find was that of the cabbage maggot. https://extension.umaine.edu/ipm/ipddl/publications/5005e/

The cabbage maggot is a very destructive insect, attacking crucifers such as cabbage, broccoli, cauliflower, brussel sprouts, radishes, rutabagas, and turnips. All cool-season plants. Wilting leaves are usually a sign of maggot damage and indicate that roots need to be checked for maggots.

What plants are you growing that appear to be getting attacked?

Ootockalockatuvik, your source says cabbage maggots grow to a max 1/4 - 1/3 inch long and they attack cool season brassicas. There's no scale in the OP photo but going by the soil particle size they appear larger than that and it's midsummer. We're not told what plants they're on.

Just trying to help. I would hope my link to a horticultural pest ID website would inspire the poster to look around and measure their pest to ID them. As for brassicas, I'm in zone 7 with 100 degrees this weekend and Kale is happily growing. The poster had no location, for all I know they are growing broccoli in Alaska.

I'm terrible with larvae, but the scale on this would be that they are in a 1/4 cup measuring cup, which isn't very precise, but I would guess the handle is about an inch or a little less across, with the edge of the vessel being 1/8 to 1/4 of an inch ... at least based on most plastic measuring cups I've seen. I'd guess those larvae would be roughly 1/4 to 1/2 an inch ... but I'm estimating, and the measuring cup could be different from my assumptions.