Insect Verdict

September 28, 2010

Dr. Gillian W. Watson, California Pest Prevention Service’s Entomology Lab, emailed the results regarding the plant sample that I mailed last week for scale identification.  Dr. Watson recognized the scale on my “Stairway to Heaven Jacob’s Ladder” (Polemonium reptans) plants as Coccus hesperidum, Common name Soft Brown Scale, C rated (native insect).

Dr. Watson also wrote, “Unfortunately, as an identification lab we cannot advise you on how to control them. Your County Agricultural Commissioner’s office can help you in that way or perhaps your local Nursery.”

Instead of contacting the suggested services, I turned to my Pests of Landscape Trees and Shrubs book for a quick read. Fortunately, Soft Brown Scale seldom causes serious damage. One recommendation is to treat with horticultural oil during dormant season or in spring when crawlers are active. The text also suggested removing heavily infested branches. Unfortunately, most of the stems and leaves on my plants were extremely infested. As I shared before (see September 22 post.), I opted to pull them out.

Although I lost two of my favorite plants, I view this backyard experience as a learning tutorial:  Examine my plants closely at the first sign of trouble, and send a sample for insect identification ASAP.



  1. You’re right about pulling out heavily infested plants. I have a favorite house plant that was given to the family when my brother died many years ago. It got mealy bug one summer when I set it out on the patio. I have treated it every year since but can’t completely eradicate it. This morning I took a look at it and it was again showing signs of mealy bug (and I didn’t put it outside this year). I am now ready to put it in the garbage can.


  2. Another important aspect of scale control: look for ants. Ants herd scale as well as fight off beneficial insects. If you see ants climbing in your scale-infested plants, put out ant baits. Soft scale can also be controlled with a forceful spray of water into the plant (if the plant can take that kind of force!).


  3. To eraddicate the mealy bugs on my cactus, I tried rubbing alcohol. Bought 4 bottles, of 59 percent at the 99 cent store and used about 2/3 of one bottle to douse six cactus. Hope that does the trick for me. I also re-located a livelady bug i found in a tree fern to the cactus area. I believe lady bugs are good mealy bug eaters.

    Also re-plants the ‘specimens’ of cacti & succulents we got at the last cactus meeting. they are doing fine! punched holes in the plastic planters now these plants are ‘portable’ as we discussed earlier. I can move them to different parts of the garden sun/shade if they dont’ do well where i first place them.

    Most of my ‘plantings’ do well with little moving about, it’s just by chance that I place them where i do initially, but sometimes they need a different home.


  4. I totally agree with what you did, when you had plants that were totally infested with soft brown scale you opted to pull them out. That is exactly what I would have done. If I loved the plants I pulled out I would start fresh with new ones in new dirt. If those plants become infested, I would chose a new plant!!


  5. Ants can cause a lot of havoc with our plants, bushes, and trees. Besides herding scale as Fred just commented, they harvest aphids too. This year has been a horrible year for us as far as aphids are concerned. They are on my crepe myrtle trees, some of my Japanese boxwood ( I have hundreds planted), some of the leaves on the birch tree are shiny and the aphids were very plentiful on one of my succulents. We have been busy trying to do away with the ants.

    Mealy bugs are extremely difficult to get rid of and if it were not so sentimental to you Betty, I would dispose of it. Try Bernadine’s fix (I have heard of that before) Good luck.


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