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Scale insects on hibiscus

Just found scale insects on a large Hibiscus indoors. It s been years since I had these on anything, and never on something so big. Is there a particular spray that is good, or do I need to pick them off one by one? Or pick-then-spray?

Comments (11)

  • birdsnblooms
    14 years ago

    Hi Linnea56. First, isolate your Hibiscus from other plants.
    Hand-picking works, but depending on the amount of scale, it's a slow and long process, plus by not spraying, you're only removing older bugs, missing eggs and crawlers (babies).

    I don't use chemical sprays for a couple reasons, one being we have birds. Chemicals can kill a bird and who knows how harmful it is to other pets and people.

    When it comes to insecticides, I mix my own natural/organic ingredients, ingredients depend on type of insect.

    The best method I've found killing scale is by foliar spraying Fish Emulsion. FE's main use is organic fertilizing, either by mixing with water, then applying to soil or spraying leaves/foliar feedings.

    I was told this useful tidbit from a citrus nursery owner in Fl. She uses it as a preventative on Citrus trees.
    1 capful of FE, warm/room temp water, in a 16 or so ounce spray bottle. Shake thoroughly. Spray all portions of the plant, upper and lower leaves, stems, trunk, everywhere.
    Spray a second application a week later.

    Linn, FE does the job. The only problem is it has a fishy odor. The smell lasts 2-3 days depending on ventilation in your house. On warm days, crack open a window. There is an odorless FE, but I've never used it, so can't vow if it's as odorless as they say. lol.

    Since our temps warmed up, you can bring your Hib outside, spray, and let sit 1-3 hours. Don't forget to bring Hib back in at night. As long as temps are 55-60F and up, you haven't any worries.

    There are other oils, and/or chemicals, but I prefer FE. Good luck whatever you choose. Don't forget to isolate Hib, Toni

  • jeannie7
    14 years ago

    Linnea, the most common method used to treat oyster shell scale insect is with rubbing alcohol which is applied in different ways.
    One is to use a Q-Tip, soaked in the alcohol and the bug is then touched. The alcohol eats through the hard shell and kills the bug. Each bug though must be touched to be effective.

    The other method is to treat the plant.
    In a quart spray bottle, put 20 oz water, one tablespoon of dishSOAP and 4 oz rubbing alcohol. This amounts to about a 2% solution. If you feel it might be too strong, double the amount of water/half the amount of the other.

    Take the plant out where you can spray indiscriminately and spray from top to bottom, bottom to top, ensuring all parts are covered.
    Wait ten minutes, then rinse wellw ith tepid water. Again, from top to bottom, bottom to top and let's not forget to treat the soil as well. That's where the children are.

    This method must be repeated 3 times in 20 days to break the cycle of the bug from egg, to larvae, to adult.
    Then constant vigil is needed.

    Another method is to use the dormant oil that is used outside in combo with lime sulfur.

    Most plant bugs can be treated with the soap and water without concern of damage as long as the soap is not left on the plant.
    Most bugs can be treated initially by simply hitting them with a stream of water.

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  • linnea56 (zone 5b Chicago)
    Original Author
    14 years ago

    Thanks for the help. Where do you find Fish Emulsion? I have heard of it before as fertilizer but have not seen it in stores. Is it a liquid or a powder to be mixed?
    If I go the soap route: I use something like the Dawn dishwashing liquid I have? Or is that too harsh? I have heard of using insecticidal soap but never knew it was to be mixed with alcohol. When you rinse it off, arenÂt you rinsing the solution into the soil of the pot. WonÂt that hurt the plant?

  • rhizo_1 (North AL) zone 7
    14 years ago

    linnea, do you know what kind of scale your plant is infested with? It might make a difference with the control method.

    If you don't want to mess with the fish emulsion, you might want to try a general horticultural oil. (It's the oil in the fish emulsion that helps control the scale.) It won't smell. Oil applications, by the way, are typically recommended for the control of scale insects. Fish emulsion (yes, a fertilizer) is a liquid and can be found in any garden center department. So can an assortment of horticultural oils.

    You can try an alcohol application by mixing one part isopropyl to 3 or 4 parts water (some people even use it stronger) and misting the leaves and stems. You don't need to rinse it off. Avoid dish detergents. Dawn, in particular, has a bad reputation for burning foliage.

    Please do not even consider applying lime-sulfur mixes in conjunction with oil applications. I think that jeannie is trying to kill your plant, lol. Also, you do not need to treat the soil. Scale insects lay their eggs on the plant, they hatch on the plant, and live their entire life on the plant.

  • Mentha
    14 years ago

    FE does work on scale, however you will still need the soap to wash the buggers off the plant. Alcohol would burn a hibiscus, happens every time for me. I would go with the soap, if you must make your own, use soap flakes found in the laundry aisle. Mix a couple tablespoons in a squirt bottle with a bit of glycerine and a bit of garlic oil, and it should not only kill them but repel them.

    Another thing I have used with success is fly spray for horses. It has a citronella scent and scale does not like it.

  • linnea56 (zone 5b Chicago)
    Original Author
    14 years ago

    The scales are rather large, about 3 to 4 mm, and black or very dark brown. Not the smaller light brown ones. They are producing a lot of honeydew which is why I noticed them.

  • birdsnblooms
    14 years ago

    Linnea, Home Depot and some Walmarts sell Fish Emulsion.
    Like I said, it has an odor, but rids scale, immediately.
    FE is also sold online..Ebay, Home Harvest, to name a few.

    I use most dish soaps, except Dawn..Some people swear by it, but anything that 'cuts grease' is a little too harsh in my opinion. But it's great for

    Linnea, do you outdoor plants in summer? Honeydew attracts ants. Have you seen any?
    (If possible) either shower or hose your Hibiscus. Let air dry. Afterwards, give a dose of FE or whichever spray you choose to use, (follow instructions/dossage,) spray thoroughly. Insects hide..under leaves, between stems.

    My plants had one scale outbreak after receiving a newly purchased Olive tree. There were literally hundreds of these disgusting, huge-shelled creatures. Thankfully, I remembered the woman in Fl's advice, and followed her directions to a T. I swear, the following day, all scale were goners! A week later, Olive and neighboring plants got a second dose..this happened over 4 yrs ago..thankfully, not a scale since.

    Whatever you decide to use, good luck. Please remember, aim at all parts of plant to rid these creatures. Toni

  • linnea56 (zone 5b Chicago)
    Original Author
    14 years ago

    I just found another hibiscus with these! In a different room but both plants were from the same source. I suspect they had them secreted somewhere when I bought them. It just took a while before the population boomed and I saw them. I decided to cut off all the tips (where they are congregating) to make it easier to eliminate these. Then I only have to deal with the babies and survivors.

    In checking other plants I found spider mites too, so it looks like everybody needs a soapy bath at the least.

    Yes, they live outside in the summer. I am heading out to Home Depot to buy the FE today. Where do you find glycerine and garlic oil? I have some garlic capsules, pierce and use those?

    Let me see if I understand thisÂtake it outside and spray it with water thoroughly. Let dry. Spray with soap solution. Let sit for 10 minutes, then rinse. Spray with FE solution. Re-do sequence 2 weeks later?

  • tapla (mid-Michigan, USDA z5b-6a)
    14 years ago

    Linnea - Neem Oil is a safe insecticide you can use indoors w/o concern for your or your pet's health. It's known to be effective on insect with sucking/rasping mouth parts. I've used it to control whitefly on hibs, and I've used it to control scale and mites on many other plants.

    I'm not sure if it was this thread where someone cautioned against using alcohol on hibs, but I've used it many times with no ill effects.

    First remove as much of the scale as you can by hand. Then start with a pint of very hot water in a 1 qt spritzer. I then add a tsp of {{gwi:80434}} and few drops of Murphy's Oil Soap (or dishsoap), shake, and add a pint of 70% rubbing alcohol. Shake again and spritz, making sure to cover all surfaces, especially the underside of leaves and leaf axils (crotches). Shake frequently to keep the blend emulsified. Spray at 2 week intervals.


    Here is a link that might be useful: More about neem oil if you click me

  • birdsnblooms
    14 years ago

    Sorry Linnea..Mites too!!! Oh Lord.

    Get a spray bottle. 16oz is fine, if larger or a little smaller, no problem, but 16oz if fairly standard.

    Fill sprayer with warm water. Add 2-4 drops of dish soap. Your Garlic capsules are perfect..yes, pierce the capsule, squeeze gel inside water.
    Got any lemon or lime juice? If so, add about 1/4 teas to water.
    1 capful of Fish Emulsion. Add to solution. After capping, shake vigorously..all ingredients should be well-blended.
    Then spray away. Good luck, Toni

  • linnea56 (zone 5b Chicago)
    Original Author
    14 years ago

    I got the fish emulsion yesterday. ItÂs going to be warm outside today, IÂm going to do this. First have to find some non-dawn dish detergent around the house. Forgot that yesterday. I do have MurphyÂs oil soap mentioned by another poster.

    IÂm not clear about this: First I spray it with soap solution, then let dry, and re-spray again with solution of FE, water, soap, and garlic?

    Or am I spraying only once with the combo FE solution?