Having an insect problem w/my avocado plant

[babs15]

Hi all, Couldn't figure out why I had these little tiny black flies around the house every now and then. Well, today I put my glasses on and looked at the pot that my avocado is in and lo and behold there are these tiny bugs, flies (fruit flies??) I don't know what they are. What can I do to get rid of them without killing my plant? Any help would be appreciated.

[applestar]

Most likely fungus gnats. Is your avocado healthy? If not you maybe overwatering and not letting the soil dry enough in between.

Set out a wide container of soapy water next to the plant. fungus gnats love to drown themselves in them. I use my kids' shampoo that smells faintly of violets, but I think you can use anything as long as they're not insect repelling like lavender, mint, eucalyptus, etc.

If the soil is allowed to dry on the surface the way avocado prefers, I think fungus gnat larvae will not thrive. So let's go from there before taking more drastic action.

[babs15]

I will immediately try your remedy. I was watering it once a week. Maybe that was too much. I will report back after awhile. Thank you again

[applestar]

I just wanted to tell you that my bowl of soapy water is quite full with the gnats. Every morning (I have to put my glasses on to do this) I have been inspecting the base of my avocado plant. I still see activity. Oh, I forgot to say that I also filled a spray bottle with soapy water and that also has been terrific. There are many dead bugs on the floor after I spray. I don't know how long this is going to go on for. Any thoughts on that? Thanks again, Barbara

See! They can't help themselves.

Killing the adults will help to break the cycle and you should be seeing less flying around. I believe watering with the same soapy water will weaken or kill some of the larvae. I also dust the soil surface with diatomaceous earth powder -- BE SURE to use the raw agricultural/horticultural kind (or human consumption supplement if you want to spend the money) and NOT the heat processed pool filtering kind which is hazardous -- to pierce the larvae and kill them when the soil surface is drying.

But seriously you can get DE from good garden centers and feed stores because they are added to animal feed against the bugs in them and some people use it as livestock wormers.

Typical timeframe for eliminating most if not all pest infestation is two weeks of regular treatment.

You are almost there.

[babs15]

I am a big baby when it comes to using chemicals (I'm afraid to use weed killer outside) so I will stick with my soapy water routine and keep my fingers crossed that it will eradicate them. I am so happy I found this website and have people like you that are so helpful!!! Thanks again

[Green Mantis]

I bought some of those yellow sticky things, you put on the plastic stick that is provided, and they are dead all over it. So they definately work. Real easy to change out too. I have a big tank beside those plants, that has moist soil in it, for my 4 pet Salamanders, that's what attracts them.

[cynthia_h]

As of last fall (approx. October 2010), there is also a very fine-grained formulation of diatomaceous earth available in pet-supply stores. It's quite safe. I purchased a container and now add DE to my cats' food twice a week for internal flea control. (External flea control on the two cats is flea combing.)

I could use DE in the dogs' food, but the $ would be prohibitive. Instead, I use another $$$ product: Comfortis, whose active agent is spinosad.

Cynthia H.
Sunset Zone 17, USDA Zone 9

[applestar]

Yep. DE is completely natural, ground up mineral-like mass deposits of ancient dead sea planktons. The skeletal remains are microscopic sharp shards that can pierce the soft bodies of insects where their "armored" exoskeleton meet, like in joints and between abdominal segments.

There are some possible environmental issues with digging them up and "mining" them, if you have concerns in that area.

Once they are high heat-processed and puffed for pool, etc. filtration purposes, the shards become brittle and dangerous when inhaled, like fiberglass and asbestos. Hence the warning.

[babs15]

I still keep a bowl of soapy water next to my plant and I change it every week. There are always plenty of gnats in there as Applestar had told me there would be. But it never stops. I do notice it is slightly less but they are still coming. Other than the DE is there a spray I can use that won't kill the plant? My other question now is that the lower leaves of my avocado plant have brown circular spots on them. Is this due to overwatering or something else. Any advice would be appreciated.

[froggy]

Fungus gnats eat mold in the soil. Get rid of the mold, and the gnats will disappear. First, let the top of the soil go dry before watering again. Second, cinnamon kills fungus, sprinkle a bit on the soil, or keep a stick in your watering can - don't overdo it though, it can burn your plants roots...

There is a thread on fungus gnats in the container gardening forum here - read through that for more ideas...

[babs15]

I will try the cinnamon and I just read that info. It seems to have worked for many others. Hope it will work for me too! Thank you again

[babs15]

Thank you so much for the cinnamon tip. One application and I couldn't believe how few gnats there were in my bowl of soapy water sitting right next to my avocado plant. Wow! amazing. My only problem now is why are the leaves developing large brown spots. I've pulled them off but if it continues before I have to ditch my plant I might just plant it outside.

[froggy]

Too much cinnamon can damage the plants roots - I believe I mentioned that... Keep the environment stable, remove any cinnamon residue and don't use any for a while. Make sure you don't over water the plant. If the roots are damaged, it will need water less frequently - use the chopstick method to check how dry the soil is...

[ladybug1970]

Hello, I have a question for applestar hopefully he or she gets it, but I was reading your post on the soapy water for the gnats and wanted to know how much water to soap. I'm having the same problem. Thanks

[rainbowgardener]

here's a thread where I recently replied to someone else about the fungus gnats: https://www.helpfulgardener.com/forum/vi ... ts#p402961

The soapy water spray would be a tablespoon or so of liquid soap in a quart of water. If you are spraying the leaves of your plant, I would use real soap (e.g. Dr. Brunners, Murphy's oil soap, etc) not dish "soap" which is actually detergent. Detergent can burn the leaves.

[applestar]

If ladybug is talking about containers of soapy water for the gnats to dive into, I just put in a dribble to a squirt of liquid soap then water from the faucet -- the resulting solution should have sudsy foam on top to begin with, though the bubbles will subside.