I thought this was sap until I was told it was scale (by someone who did not see it or the attached picture). It's on both of my Kaffir limes, just on the leaves (which appear healthy). It's on about one of four leaves, and appears perfectly clear.

The two Kaffirs are still indoors, but have recently woken up from winter and have been putting out a lot of new growth...so I'm pretty sure it's just sap (the little tan specks are sawdust, btw). Is it?

Thanks!

Although, I cannot see details very well on your picture, I doubt that it is sap. I would say the stickiness is from scale or aphids. - Millet

If that's realy sap, well spray your tree with a copper fungicide, because sap extrudations from buds and leaf breath openings is a symptome of copper deficiency....
But the picture isn't able to tell me that, it's simply a guess...

If when you touch a tissue or paper towel to the leaf it comes away green than it is sap. I know that I had an orange tree that did something similar, but for my poor tree it was the sign of a mite infestation under the leaves Never again will I believe someone who offers to spray my trees before bringing them into the house for the winter. I noticed it too late (I was sick/not feeling well at the time) and lost all but one orange tree which has fortunately mostly recovered from that experience...at least it's growing again & the new leaves are unaffected & pest free.

Cat