Insecticides - Systemic Granules Vs Neem/Alcohol

Davenport, IA

I have fungus gnats coming from a couple of plants, I have spider mites on others.

I got my neem oil, and have mixed 1/2tsp with 8oz water, 8oz 70% isopropyl.

I also have fertilome systemic insecticide granules.

From what I gather, I need to spray the neem mixture several days for three weeks... and then when the weatehr gets warmer, and I put my plants outside, I will potentially have problems with bringing bugs back into the house on the plants. Not to mention, if I go to the plant store, I may end up hauling mites or something else home on my clothes or hands, and having to go through the neem deal again.

Also from what I gather, if I just use the insecticide granules, I will need to just re-apply them when it expires, and won't have to worry about bringing bugs home so much?

I've literally been reading for about 3 hours here, trying to decided which route to go. I have about half of my plants in the gritty mix, waiting to transfer the rest from dirt until later this year, unless they begin to look bad. (All of my seriously bad looking plants have been saved by the transfer! ...with the exception of one, maybe.. it might be too soon to tell)

I'm interested in which of the two products more experienced forum members would use and why?

Thanks so much.


Bay City, MI(Zone 6a)

Usually the gnats, more of a nuisance than a problem themselves, indicate over-watering. The gnats are attracted to moist soils that are 'breaking down', so managing your watering so the top inches of soil go dry before watering again, makes your soil less attractive to gnats. If they get so bad you need treatment, mosquito dunks work if they specifically contain Bacillus thuringiensis subsp. israelensis (Bti), as do yellow sticky cards. The most effective treatments (other than good watering habits) are those that are persistent; killing adults for up to three days. A number of pyrethroid-based insecticides, with extended persistence, are available for use on houseplants including those containing: bifenthrin, cyfluthrin, permethrin, and lambdacyhalothrin. Short-persisting contact insecticides such as those containing pyrethrins, soaps, oils, do not provide sufficient long-term control of fungus gnat adults and require repeat applications at short intervals to be effective.

The systemic insecticide imidacloprid, which is (prolly what's in your granules) will also kill fungus gnat larvae when applied to the growing medium. This active ingredient is available in a number of houseplant insecticide formulations as granules, slow-release “spikes”, and in combination sprays with a pyrethroid-based insecticide.

I never have problems with gnats because the gritty mix is a very inhospitable environment for them, and I like to think I have my watering habits pretty much down pat by now, but if I did, I would always try the least noxious remedy first, and chemicals last.

Best luck!!


Salem, MA

Dear Al,

You said, "A number of pyrethroid-based insecticides, with extended persistence, are available for use on houseplants including those containing: bifenthrin, cyfluthrin, permethrin, and lambdacyhalothrin." Could you name one or two specifically? I'm fighting spider mites on a needlepoint ivy plant, and have been having trouble finding an insecticide that contains Bifenthrin that I can use on my house plants.


Alum Bridge, WV

If I can't control pests with insecticidal soap, I toss the plant before it cam infect others. Mites especially merit a toss into the garbage. This has worked for me for nearly 60 years....................

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