Below is a picture from a customer who asked the question, “What are these in my bin and are they harmful to the worms”? These are probably black soldier fly larvae. They are a little unsightly, but are good composters in their own right and are not harmful to your worms. These tend to show up in my manure piles when the weather heats up. I will remove them most of the time from my worm bin if they show up, but it is not necessary.
Texas Jumpers 
Other photos of the black soldier fly larvae are black and my ‘larvae’ are definitely whitish. Could mine be a different critter? I don’t want to risk my bins health if they are indeed harmful
Don’t think it’s an issue. If you are concerned at all you can pick them out.
There is a compost bin with full of okd cowdung in my garden which was left for a long time say 6 months. Now when I opened it I found these worms inside. To my surprise I saw the cow dung was fully converted into very light black soil like vermicompost. Definitely it was the outcome of the presence of these white worms. I think it’s not larvae rather full fledged worms.