Need to kill insects on herbs indoors

gosssamerFebruary 5, 2014


I've been trying for the last few weeks to kill small little bugs on my basil and cilantro plants growing indoors. I went through a whole bottle of Safer, tried vinegar and water, and washing each plant in the sink individually. Nothing so far has worked completely.

I've looked online quite a bit for other methods to attract/kill these various bugs, but have been unsuccessful. Does anyone have any other suggestions for dealing with them?

I'm thinking it's the eggs that aren't being killed?


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balloonflower(5b Denver CO, HZ 5-6, Sunset 2b)

You don't say what the bugs are. The most common in indoor herbs are fungus gnats (little fruit fly lookin critters that you'll see flying all over), whiteflies (itty bitty white moths) and spider mites. Aphids are another possibility, and more destructive.

The thing with the fungus gnats is that they live and breed in the soil, so they're harder to get rid of than whiteflies and aphids which leave eggs on leaves that can be washed off or dealt with using a neem spray. I generally just manage them with the sticky traps. For aphids and whiteflies, I use neem oil spray.

Here is a link that might be useful: houseplant sticky traps

    Bookmark   February 6, 2014 at 11:08AM
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I believe I may have aphids (which have mostly been eliminated) and the black little flying fungus gnats. I don't think they're spider mites because they're flying.

Now I'm bummed. Now that you've helped me to identify them, I'll try and search further about how to eradicate them, unless someone has any further pointers?


    Bookmark   February 6, 2014 at 12:42PM
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balloonflower(5b Denver CO, HZ 5-6, Sunset 2b)

The aphids can be eliminated by washing leaves/dishsoap/neem/lots of squishing. Just needs a lot of vigilance. The other control I've heard for fungus gnats is to introduce a predatory (to the gnat) nematode to the soil, but I haven't ever had the problem bad enough to pay the price for the nematodes. I have tried sand/rocks on top of the soil with no help. They like moist soil conditions, so letting the top layer of soil dry out does help a little, but only so much. My worst infestation was last winter, where they came in with some cheap potting soil.

    Bookmark   February 6, 2014 at 4:44PM
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gjcore(zone 5 Aurora Co)

Dealing with fungus gnats is an ongoing problem here though I usually keep them in check. Try to get all your containers dried out as much as possible without injuring your plants. Running a fan in the room will help a lot. Then water all your plants with a neem oil solution. Keep the fan running as much as possible. When the containers are getting dry again repeat the process at least once more.

    Bookmark   February 7, 2014 at 9:25PM
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Thanks so much for your help.

I've done some additional reading, and I'm currently in the process of letting the pots dry out as much as possible, and also have a fan running next to them.

Next I plan to mix a 3% concentration of hydrogen peroxide with 3 parts water. Apparently that kills the larvae. The pots should be dried out enough to do this tomorrow, so we'll see.

Any thoughts on this?

    Bookmark   February 8, 2014 at 9:06PM
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seysonn(8a WA/HZ 1)

If you keep the top of soil in pots fully dry, it is unlikely that any fungus or pest will thrive in there. I cover my seedling pots with about 1/2" pine bark (1/4" to 1/2" nuggets) Also, bottom-water them. So the top stays dry all the time. I have had occasionally gnats and sprayed with chamomile tea. As you have discovered, a small fan and air movement can prevent fungal growth.


    Bookmark   February 10, 2014 at 12:08AM
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floral_uk z.8/9 SW UK

Is it warm enough to stand them outside a couple of hours occasionally? Fresh air does wonders.

    Bookmark   February 11, 2014 at 8:39AM
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Nope, it's been below freezing here in northern NJ for weeks, and hasn't been above 50F since Sept.

I tried the hydrogen peroxide with water mixture, and I think it helped a bit, but certainly didn't get rid of them.

I'm not sure bottom-watering is really practical for me.

I'm now fearing it's going to kill all the hard work I've put into this for the past few months.

    Bookmark   February 11, 2014 at 12:56PM
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floral_uk z.8/9 SW UK

How many plants do you have? To bottom water you just need to stand the pots in a container of water and then let them drain thoroughly. It's pretty straight forward.

    Bookmark   February 11, 2014 at 4:44PM
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I have about a dozen pots, all within a reflective tent in the basement with no sink.

There isn't enough room left to support another container below each pot. I could probably use some sort of tray, but I'm not sure where to get one that would be supportive enough to hold the pots and the water, yet thin enough to actually fit.

Would I then have to drain the water to avoid it stagnating?

Also, while it says I should receive a copy of follow-ups, I never receive them. Any ideas why that might be?

    Bookmark   February 11, 2014 at 7:58PM
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Well, the hydrogen peroxide mix didn't do squat. It seemed to work for a day or two, but they're back in full force. I now have a spray bottle called Eight that's supposed to kill them.

We'll see what happens in a few days.

    Bookmark   February 14, 2014 at 7:25PM
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chervil2(z5 MA)

I realize that this winter is extremely cold with very few days that are warm enough to place your plants outside for a few hours. However, a couple of weeks ago, I brought all my plants outside so that I could thoroughly clean the entire inside area. Outside, the plants were exposed to UV from the sun and wind that helped to remove many of the insects. Spraying with a hose helped as well. I am overwintering peppers that are infested with green aphids. Interestingly, some Asian ladybugs have taken up residence on the pepper plants and seem to be eating some of the aphids. I have heard that one ladybug can eat 200 aphids per day.

    Bookmark   February 14, 2014 at 8:33PM
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Now there's about 36" of snow on the ground. All the ladybugs are dead or frozen, along with the hose :-)

It's supposed to be 55F late next week. Maybe that's an opportunity to bring them outside, if I can find a nice warm spot on the walkway outside or something.

I'm very disappointed the hydrogen peroxide didn't work.

    Bookmark   February 15, 2014 at 8:56PM
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