I don't see any "worms" on your fern but the damage looks extensive. Those worms are caterpillars, leaf chewing insects that are the larvae of butterflies and moths. I do suggest you cut back the damaged fronds and give the fern some diluted fertilizer, such as fish emulsion, to encourage new growth.

The first step to solving the problem is picking off the caterpillars and throw them in a bucket of soapy water. Do this over a period of time.

The Pacific Northwest Insect Handbook has information on the life cycle of these pests and their natural enemies. Here is the link https://pnwhandbooks.org/insect/hort/landscape/common/landscape-caterpillar

A link within the Handbook will take you to information on chemical controls, which includes organic controls. Several pages in you will find controls for chewing insects and look for caterpillars under that.

A very hungry caterpillar can do a lot of damage in a short time, as their sole mission in life is to eat and turn into a moth or butterfly. As the fronds grow back continually check for caterpillars on and underneath the fronds. Watch for and destroy eggs on leaves and on the soil around the plant.

I have looked through a couple hundred photos of caterpillars and its moth/butterfly in the publication Lepidoptera of the Pacific Northwest and saw a couple of caterpillars that look like your picture, but the description of what specific plants host the caterpillar does not mention ferns. https://www.fs.fed.us/foresthealth/technology/pdfs/FHTET_03_11.pdf

There are several recipes on the web for homemade soap and water formulations, but none have been scientifically tested for effectiveness and safety for the plant. The link I sent you previously lists Bt as being effective insecticide and insecticidal soaps. Both would be organic.