All sorts of animals eat our food. Id'ing one from a damaged fruit is pretty much impossible to do.

Thanks. So far I have ruled out squirrels.

i guess it is fair to say you can also exclude deers ;)

but seriously, i think a number of bugs could do this.

I have been looking at the plant and haven't seen any bugs. There is sometimes something that looks like a cross between a spiderweb and a cocoon that can span the center of a small leaf - I am sure a bug was in there at some time...but the ones I have picked through *seem* to be empty. I'll take a picture of one of those and it may narrow it down.

Snails/slugs most likely, second possibly would be earwigs, but since the damage is round, it is most likely being caused by snails. It can also be rodents, but not usually at this stage (too bitter for rodents at this stage.) Do you have snail damage on your leaves? Very hard to tell with just this one photo. A photo of the tree, and close ups of the damage would be more helpful. We have terrible issues with snails here in S. California, and this to me appears to be just that. Snail bait at the base of your trees and hand picking out the snails from the tree (look under the leaves, go out in the early morning or evening when they're active helps to find them in the tree) are your choices. Sluggo if you must have organic, Deadline liquid squirted in a couple of concentric rings around the tree, if you want serious treatment. I usually do not recommend metaldehyde pellets if you have small children or dogs, as it is quite poisonous, and dogs are attracted to the metaldehyde pellets. Sluggo is simply iron phosphate, which just degrades to iron in the soil, eventually, but is fatal to snails and slugs.

Patty S.

patty i would not have thought that snails will go up the tree even though for a very short time is crossed my mind but thought this would be from fruits on the ground.
i remember long time ago we placed copper bands around our veggie beds. but since copper is so expensive theese days it is not very economical i guess.
i small band with sharp sand mixed with some DE around the trees probably would help too?

Are you kidding?!? A snail continues to climb to the very top of the tree or to the tips of the branches, where the more tender leaves (any fruits) are. They will eventually make it to the very tippy top of a tree. Citrus trees are probably the biggest snail attractor of all landscaping materials I can possibly think of. Oh, maybe second to Hostas. But almost equal to Hostas. They will stay in the tree, hiding under leaves during the daytime. I have had very young citrus trees nearly stripped of leaves and fruit. Forget the copper bands, worthless. I've tried it on my trees, planters, etc. They just crawl right over the copper. DE might help, but it just gets washed into the soil, so unless you're up to re-applying every few days, I'd stick with Sluggo and hand picking. Sluggo is 100% organic and eventually degrades to add iron back into your soil. Perfectly safe, and in fact, safer than DE, which you should apply with a mask (btw).

Patty S.

Here is a link that might be useful: UC IPM: Citrus and Snail Management

yes DE is not as harmless as it seems ( for the user at least )
no patty i was not kidding as i have not seen any snails in my trees. but this might be because i'm in michigan?
to be honest, to live where you are with that awesome backyard of yours, i'll take the snails any day and pick them up :))
have you tried Guinea fowl?

thank you for the link :)