I don't know whether you are noticing honeydew..which is a bi product of aphids or not?? Honeydew is sugar so it is sticky.Take a close look for any type of insects and if so treat as necessary.

It is just one sticky drop per leaf attached underside where leaf starts.

****one per leaf.

Thank you rosco.

Best wishes ,
Radovan

I hate to resurrect an old thread, but this exact thing is happening to me. I grew a hibiscus rosa-sinensis from seed, and now I'm getting one single red drop on the underside of almost every leaf, where the leaf meets the stem. In my curiosity, I licked one. It tasted sweet.
I didn't see any other signs of an infestation of any sort. Radovan, did you ever find out what was up with your plants?

My friend just took some clearer shots

Here's one with flash

You are correct. If you lift the leaf of a hibiscus you will see a small droplet of nectar produced. This is to attract insects that can provide predatory protection. My issue is that ants want to have their cake and eat it too. Along with the ants come their bud sucking friend the aphid. Neither are welcome in my flower garden.
Ed

Wow, I'm impressed. I've never been accused of being very observant but there is not way I'd ever notice that one little imperfection. You should be commended for the attention you give your plants.

Thanks Jonnie for sharing that.

Darren

Very similar thing happened to my hibiscus but only with crystal clear sugar sweet (yep I tasted them too) drops. So I've been wondering why and came across this page. Internet is one good invention...

I appreciate "radovan" for sharing this problem 7 yrs ago and also many thanks to "JonnieSilvs" & "Gutzmek" for enlightening us.

Best wishes from Turkey.

Zeki

This is also happening to me, but my leaves are yellowing and dropping. One clear drop on the back side of several leaves, plus dropping leaves. Is that still to attract nice bugs?