I'd say that was the larvae of the black soldier fly, your bin must be outdoors. They are good at consuming large amounts of organic material in short order. The larvae themselves pose no threat to your worms. The adult BSF do not bite and are not known to transmit pathogens to humans, they don't even eat. Since they don't eat, you likely won't have issues with them buzzing around your food. Because of their short life span as an adult fly, they have no working mouth parts. They have the singular goal of finding a good lookin' fly, having sex, laying eggs and then dying.

In large numbers they may out-compete your worms for food and space but this may not be a problem. If your bin is large enough, the BSF will feed at the surface and the worms should be able to dive into the compost below and hang out there. The BSF poop should contain enough micro-organisms and undigested organic material to keep your worms fed. If you have really large numbers of larvae you can try using a netting or screen to prevent more eggs from being deposited in your bin.

Another issue people find with a lot of BSF is that it makes their bins wet. I don't think it's the worms wetting the bin so much as they are consuming the organic material at a rate faster than the worms do and the moisture that would normally evaporate does not get the chance to and sinks down the the lower compost.