not sure on the split, maybe frost damage, or too much moisture around the base. if your trees are healthy, they should be putting out new growth now. try posting in the Citrus forum.

Thanks for the responses. That does make sense considering I have a Meyer lemon is doing the same thing on the branches that froze also. Does this indeed heal over time? Is there anything I need to do?

John, I know not all mites are created equal :-) I'm a Master Gardener, and have some knowledge about pests and their beneficial predators. I'm not an expert by any stretch, either, and not an entomologist by a long, long stretch (I'm a nurse, actually). But from everything I can find, and I have looked at about 10 sites, the Montdorensis is teeny, tiny. And they don't seem to look anything at all like these large green bugs which appear to be about a 1/4" long. Montordrensis appear clearish. Not with this very distinct, green hard shell. I looked through the link you included, and the only photo I can see for this predator mite is the one I have in my post above. Where are you seeing these gigantic predator mites (relatively speaking, as mites for the most part, and very, very tiny) on the link you provided? I must be missing the photos. Willing to be educated. Patty S.

In fact a navel orange is actually a small orange growing inside the larger fruit. As for the insect damage, I am not expert in this field; but it looks like mite damage; it occurs early in the life of the fruit and the most common symptom, as you have noted, is the fruit colors prematurely. I sometimes get this in my garden Meyers that are not systemically protected from insects. Nothing you can do about it; the damage is done and the mite is long gone. In the future get your 10x loupe and check for mites early in the flower/fruit development; if you find them, treat accordingly, or as I do in my field trees, protect them with a systemic insecticide.