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Posted by gardenspuds CA- SF Bay area (My Page) on
Thu, Oct 21, 10 at 17:15

I went to water my orchids today, and noticed what I thought was white fungus on one of the Phalaenopsis, but on closer inspection, I saw an oval insect. Looking in one of my orchid books, they look like Mealybugs. The largest one is 1/4".

The book I have recommends removing with a cotton swab dipped in denatured alcohol and then spray weekly with insecticidal soap. I don't have any denatured alcohol, what can I do instead? I'd like to stay organic.

I haven't introduced any new plants in about a year, wonder how they got there! None of my other plants show any bugs yet.

Do I need to change the potting medium or sterilize the rocks in the humidity tray?


Follow-Up Postings:

RE: Mealybugs

Vodka or gin. Spray the whole plant except flowers or buds. Wipe off any bug bodies that are visible and spray that part again.

Glass cleaner works also. Even dish soap and water will kill some if you have no rubbing alcohol.

RE: Mealybugs

You can use the alcohol from the drug store.

RE: Mealybugs

Or the nasty tasting not flavored Listerine mouth wash .

RE: Mealybugs

Mealybugs are a major problem for Phals and need to tackled vigorously and often until eradicated. rubbing alcohol(applied on the infected areas with a cotton bud) is good, but be sure to treat the eggs and immatures(looka like a white dust) as well as the mature bugs, make sure you look in the leaf crevices. go back every two weeks until you are sure you have gotten rid of them otherwise you stand a high risk of losing the plant.

RE: Mealybugs

Hi Barbara,

1. Oak Hill Gardens' Nov. newsletter addresses this very topic. I didn't realize that, when threatened with sprays, alcohol on Q-tips, etc., mealybugs hide in places on the plant that spray might not reach or in the media, where they eat roots. They may travel to other plants, even cork mounts. Ick!

Oak Hills' sure-fire remedy for a big infestation is to soak the bare root plant in "the insecticide of your choice," then dip everything else - labels, pots, wires, rings, clips, etc. in a solution of 10% bleach.

They treat plants w/ only a few mealybugs w/ insecticidal spray, including spraying the medium. However, with their # of plants, they probably don't have the luxury of using a Q-tip dipped in alcohol - yes, regular rubbing alcohol from Target, the grocery store, etc.

Oak Hill staff is responsive to questions, and you could ask about the most organic insecticide that might be effective. (The info here isn't complete, so please read the newsletter if you decide to check out this method.)

2. A commercial grower gave me this recipe for insecticidal soap, and it's worked well for me:

For a gallon of water - 1/2 to 1 cup (rubbing) alcohol
1 tbsp cooking oil - Canola being preferred
1 tbsp Dawn dishwashing soap

3. These days, I use Safer 3-in-1 Spray, effective for mites, fungus, and insects. (I think it's also available just for insects.) It's listed with the Organic Materials Review Institute, but I haven't researched that - could be worthless. Active ingredients are potassium salts of fatty acids and sulfur. Right or wrong, I use it in the house w/ no precautions except rubber gloves & shutting the door to that room for a few hours cuz we have dogs and cats.

4. Also, for 3+ years, I've about 25 Phals, mostly inside, and have never seen more than 3-4 mealybugs at a time. Each fall, I take plants outside and spray with 1600 X-clude. You can also spot spray w/ it inside.

From the Golden Harvest Organics site

1600 X-clude is truly a product that's right for the times. The active ingredient is natural pyrethrum (from chrysanthemum flowers) and it is microencapsulated to work better and longer with lower mammalian toxicity potential.

1600 X-clude is a microencapsulated (timed-release) pyrethrum insecticide... labeled for use in Hobby Greenhouses, Homes, Interiorscapes and Landscapes on Potted and Flowering Plants, Foliage, Bedding Plants, Cut Flowers and Ornamentals.

Supposedly it's safe around people, dogs, and cats, but I'm extra cautious, and if I spray inside, I open windows and use a fan to blow air out, if it's warm enough, or put a towel under the door for a couple of days otherwise.

5. This site also lists green remedies for insects, including "orange peel spray" for aphids, fungus gnats, mealy bugs & as an ant repellant. Also covers outside insects.

Hope some of this is helpful. Whitecat8

Here is a link that might be useful: Oak Hill Gardens November '10 Newsletter

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