Hi Anna,
I do not have an answer to your question posted regarding gnat killer dust, but I hope you don't mind me jumping in to inquire the more experienced out there about using colored sand to help eliminate fungus gnats...I read in one of the threads on this site that if you apply a thin layer of sand that would keep these "bugger" away....I poured colored sand on my umbrella tree yesterday after I watered and I did notice there are no gnats in sight today...but now I'm worried because I don't know if the colored sand will harm my plant....I guess you can say I was desperate, since I have tried so many other ways to get rid of these creature ...I've lost approx 5 plants already....someone out there please help!

What is (or was) the active ingredient in this product? What was the actual name on the container and perhaps it can be searched. I doubt that it was called Fungus Gnat Killer Dust. Or maybe it was!!!

Chemicals are taken off the market all the time, once they've been proven to cause more problems than they fix, or enough data has come in to support major health or environmental issue in association with their use.

Anna Lisa, I can't offer any more help than Rhizo...a search shows some pest products by CIL but I don't find a dust for pests.

Juey, I didn't have any luck with a sand topping for gnats, although a TV gardening personality here who usually gives good advice says it works. My gnats didn't mind going in and out of the drainage holes one bit - I wonder if the sand isn't better as a preventative measure.

BTi (bacillus thuringiensis subspecies israelensis, subspecies is important here) is an odorless, harmless to pets, birds, people, natural larvacide that will take care of your gnats when used as a soil drench - the larvae die and breeding cycle is stopped. It's available in products like Gnatrol, Knock Out Gnats, or you can make your own solution by floating a mosquito dunk in a container of water overnight, then using that water to water your plants. Use it about three consecutive times on your normal watering schedule.

Thank you Morz, I will give BTi a try...do you think that the chemicals in the colored sand can hurt my unbrella tree? I'm thinking of spooning out the stuff before the next watering.

Does the package say what the sand is colored with? I think it is most likely harmless if it's the type usually used in dish gardens (i.e. cactus) or aquariums - did the package indicate the product was intended for something else?

Hi Morz, unfortunately, information is not inclued on what the sand is colored with...the label states that it can be used in "floral arrangements, candle displays, crafts and more"....I bought it at Big Lots for half the price of what Michael's sells it for, except that on the package of the one sold at Michael's it does mention that it can be used for fresh plants or flowers.....i may be losing a nickle to save a penny huh??? Thanks for responding
Juey

Just Google GNAT ASSASSIN.