Sticky Secretion under leaves?

[Nievesgirl]

I have little drops of sticky stuff on the main vein on the leaf where the stem is. What is this stuff ? does this mean infestation of something ? if so I guess it’s from the spider mites 

[helixturnhelix]

Sticky leaves has always translated to aphids for me

[Darkhorse]

I have noticed this too on some of my plants.  Sometimes on the main leaf vein, sometimes just on the bottom of the leaf.  My guess is that where the spider mites are slashing holes in the leaf surface, the plant "leaks."

[Charlie]

It's an interesting question, and one I've dealt with over the years. For sure sap sucking insects often excrete sugar waste called honeydew, which is sticky. Hibiscus also have sap, some varieties a lot more than others, seems to me. Sometimes this sap seems to exude from leaves but I've not seen that often. Then there is the nectar inside of flowers that would be sticky if it ever spilled out. No definite answer but since insects are the main worry here, a close examination of the sticky leaf and the leaves above it for insects should tell you if there are any there. Oftentimes we will find signs of insects after the insects have moved on or been eaten by predator insects.

Charlie