dunno about the sticky stuff. but when i get fungus gnats, i mulch the top of my pots with course sand. someone told me this a while back. apparently the sand kills the larvae. haven't seen a gnat since.

Mary, I have seen this sticky stuff on my plants at times as well (usually in very small quantities). My suggestion is to first check for critters that may be munching on the plants. The sticky stuff could be sap.

As far as the fungus gnats go, stokesjl's idea with the coarse sand is great, though I think it's more likely that the sand is killing the fungus that the fungus gnats feed on. Personally, I sprinkle ground cinnamon on the top of the soil which also kills the fungus. I've also heard of people keeping mosquito dunks in their watering cans which would definitely kill the larva.

I doubt it's the gnats: in my experience they don't do anything except make baby gnats and try to fly up my nose. A sweet, sticky substance on houseplant leaves almost always means scale, mealybugs, or aphids. What kind of plant are we talking about?

If you've tried spraying with a lot of different insecticides in a short period of time, it's possible that the sprays have interacted with one another somehow, and there's also the outside possibility that it's something the plant is doing (flowering Dracaena fragrans or Hoya carnosa drip nectar, for example, though in both cases you'd be able to see and smell flowers.), or something a neighboring plant is doing, but my bet would be that your scale problem isn't as over as you think it is.

I agree with mr_subjunctive's list of suspects with the addition of whites flies. They too will create a honeydew. Thing is, all these culprits are usually quite visible or you've already looked closer for them. Have you tried shaking a plants with the honeydew to literally see what falls (or flies) off? Anything white amongst the fungus gnats?

tj

I'm going through this right now as well. Meal bugs and spider mites both secrete a sticky substance. I have tried to spray my ivy several times in the shower and have kept it away from all other plants. Still see a few bugs here and there. I might give up on the plant because I don't want my other plants in the house to get bugs.

The plant that I've noticed this most on is a Boston fern. There doesn't appear to be scale on it, or white flies (that I can see.) It's weird because it keeps dripping on the floor too. When I shake the plant all I see is a bunch of dried up leaves. The rest of the plant is green and healthy (although weirdly shiny).

It was said: "Meal bugs and spider mites both secrete a sticky "

Mealybugs yes. Spider mites no.

The list of sticky makers -- the stuff is called honeydew -- are these
1 aphids
2 soft scale (when young, these are small ,semi-transparent, very flat, and difficult to locate. Look on the underside of leaves, alongside the mid vein.)
3 mealybugs
4 adelgids (on conifers)
5 whiteflies

Look along the stems of your fern, as well as the fronds to find the scale insects. Sticky stuff all over the leaves and the floor is a sure sign of these little pests.