It looks like something is eating new growth. What would cause this?
Certified GKH Gardening Expert
There are many pests that will eat this. Depending on if these are house ferns, or outdoor will further determine the pest. Indoor, the usual pests are insects, or fungal infection. Outdoors get very complicated. Many mammals, birds, and reptiles will eat these.
There are many ways to keep pests off of these. Neem oil works very well, as does garlic extract, and Hot pepper extract. Just be careful not to get any of this into your eyes or mouth.
This collection of articles will give you much more information on creating your own means of pest control, along with many other articles containing useful organic gardening tips: https://www.gardeningknowhow.com/special/organic/