kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

Small black flies, what to do?

I've noticed some very small (smaller than or equal to the size of fruit flies, but not fruit flies) flies that are congregating around my bonsai. These bonsai are in a greenhouse window where humidity is fairly high. However, the flies don't limit themselves to the area, but do hang around our toad tank, some other house plants, and a fruit bowl. They don't SEEM to be harming the bonsai (or other plants) at all, but they are quite annoying. They seem to have a preference for a 4" Aralia nursery pot that tends to retain moisture. Without a better description, can anyone guess what they might be and how to get rid of them?

User avatar
Gnome
Mod
Posts: 5122
Joined: Wed Jul 05, 2006 4:17 am
Location: Western PA USDA Zone 6A

kdodds,

Perhaps Fungus Gnats? I have had these occasionally but never inside. The maggots are in soil that is moist and high in organic matter. The adults don't do any harm but the maggots can feed on roots. Take a close look at the soil of the most likely host plant and check for small maggots.

[url=https://www.umass.edu/umext/floriculture/fact_sheets/pest_management/fungnat.html]Information here[/url].

[img]https://bugguide.net/images/raw/YHUHRR6HHRUH9ZEH3HIL8ZMLNZNHRRNHWZXLUZILUZML9Z5LUZWHFHXH5Z7H1HXH6ZGLBZ5LVZWH.jpg[/img]

Norm

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

Could be something related? That's very close to what they look like, but with stockier bodies. How would you rid yourself of them? Anything I can use that's safe for the plants?

User avatar
Gnome
Mod
Posts: 5122
Joined: Wed Jul 05, 2006 4:17 am
Location: Western PA USDA Zone 6A

kdodds,

The only time I have been troubled by them is when I used home-made fertilizer cakes outdoors. These cakes deteriorated quickly and became mushy. The maggots seemed to be concentrated in this organic material. I simply removed the cakes and allowed the top of my soil to dry and gradually they seemed to disappear. A lean, medium seems to not favor their presence.

Norm

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

THanks for the link. I just read through and the description of the shore fly seems more correct (i.e. it's similar in appearance, but more robust). But the problem is that there is no standing water, nor algae, in the area. So, I'm going to assume that my 40yo eyes are "off" and that they are fungus gnats. I've had great luck with biological control of mosquitos in ponds (Bacillus thuringiensis) and so Gnatrol seems like the ideal solution, being plant safe as well. It's also not effective against shore flies so, if it doesn't work, I can figure out where to go from there more readily. Thanks for the help Norm!

arboricola
Senior Member
Posts: 224
Joined: Tue Sep 25, 2007 9:07 pm
Location: Minnesota zone 4

Here's what I use to get rid of funus gnats, scale, spider mites, and aphids. Mix 2 parts 70% rubbing alcohol, 1 part water, and a couple drops dish soap. Put in a spray bottle and mist the tree if you have scale, spider mites, or aphids. lighty mist the soil for gnats. The alcohol kills on contact and evaporates in seconds. Spray once a day for 7 days, then once a week for 3 weeks.

For the flying guys I put a little Port wine in a shallow bowl. They die happy. A little sugar water works too.

Phil...

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

And there aren't any issues with the alcohol in the soil?

arboricola
Senior Member
Posts: 224
Joined: Tue Sep 25, 2007 9:07 pm
Location: Minnesota zone 4

Nope. Just don't soak the soil.

Phil...

alisios
Senior Member
Posts: 298
Joined: Sun Jun 10, 2007 3:25 am
Location: Sedona, Arizona

I've been getting a lot of these lately and I have been able to cut down drastically on the population by repotting with a less organic soil mix in all my indoor plants.

If you are unable to find items like Turface in your area (like me), I was able to ask my local hardware store (which also carries planting supplies) if they could order me some bags of Schultz "aquatic plant soil" - it's the stuff you're looking for:

https://www.schultz.com/ProductCategories/Soilsamendments/AquaticPlantSoil/

Sift through it to get the smaller pieces out.

Good luck

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

I've used that for water lilies, iris, etc., in our pond before we moved. I don't if it's where we purchased it (kind of a "high end" nursery) or not, but it's incredibly expensive stuff. I seem to remember a 10lb bag being $30. This was maybe 6 years ago, though, before we moved and, of course, left the pond. ;) If you needa source for Akadama or something similar, let me know, it's readily available from the many online bonsai sellers, including those on e-bay.

When using these "soil-less" potting media, isn't it difficult to get a nice thick carpet of moss to grow? I've never had any success getting moss established with pumice or other porous media.

alisios
Senior Member
Posts: 298
Joined: Sun Jun 10, 2007 3:25 am
Location: Sedona, Arizona

kdodds wrote: When using these "soil-less" potting media, isn't it difficult to get a nice thick carpet of moss to grow? I've never had any success getting moss established with pumice or other porous media.
I'd like to grow moss too, but being from the desert, I'd be lucky if any moss would live :(

btw, I paid 7 dollars for a 10 pound bag of that soil...

User avatar
Gnome
Mod
Posts: 5122
Joined: Wed Jul 05, 2006 4:17 am
Location: Western PA USDA Zone 6A

kdodds,
When using these "soil-less" potting media, isn't it difficult to get a nice thick carpet of moss to grow? I've never had any success getting moss established with pumice or other porous media.
At the risk of stating the obvious; soil-less does not necessarily mean inorganic. I use pine bark/mulch as my organic component. I don't worry too much about moss but most of my trees are still (or even worse, moved back to :oops: ) training pots.

Norm

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

:lol: I hear ya, being that I only got back into the hobby in December/January, everything's in "trainiing", accept for a to be semi-cascade Grewia and some accent plants.

User avatar
slx2007
Full Member
Posts: 57
Joined: Wed Mar 26, 2008 5:24 pm
Location: Elk Grove, CA

Spray the plants with "Ultar Fine" Oil monthly. I think it is the most safe and efficint way to get rid of the little flies.

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

I've ordered some Gnatrol as well as pheromone-based gnat/fly traps.

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

Just an update...

It's been 8 days since the first Gnatrol treatment. I can say that the incidence of new adults has been greatly curtailed, if not completely eliminated, as of last night. None of the trees seem any the worse for wear from this treatment (1 teaspoon per gallon in a soak) and received a second treatment last night (just in case). In conjuction with the glue traps the problem has been almost completely eliminated. :)

User avatar
Gnome
Mod
Posts: 5122
Joined: Wed Jul 05, 2006 4:17 am
Location: Western PA USDA Zone 6A

kdodds,

Excellent! From time to time we have questions in this pest and until recently I was unaware that there was a strain of Bt (Bacillus thuringiensis) that was effective. I believe that this is essentially the same product in case anyone has trouble locating Gnatrol.
[url]https://www.gardensalive.com/product.asp?pn=1962&sid=146146&eid=p_1962&bhcd2=1209047442[/url]

These products are naturally occurring bacteria that infect the larvae of the target species. There are also strains of Bt that are effective in controlling tent caterpillars and mosquitoes. A little research is required to ensure that you purchase the correct strain.


Norm

kdodds
Greener Thumb
Posts: 1436
Joined: Fri Mar 07, 2008 12:07 am
Location: Airmont, NY Zone 6/7

:lol: Yeah, control was, so far, knock wood, pretty painless. Of course, I have not researched the life cycle of the gnats (if that's the positive id). But, I'm hoping this is not a lull in the natural breeding pattern. It wouldn't seem to be since the effect coincides with the treatment and new flies were, previously, emerging every few days.

Return to “BONSAI FORUM”