Posts Tagged ‘scale insects’


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.


Battle of the Scales

September 22, 2010

Several weeks ago, I noticed that the leaves on two “Stairway to Heaven Jacob’s Ladder” (Polemonium reptans) were sticky. Thinking aphids had infected them, I hosed both plants (above photo ) off after each watering. I did this for two or three weeks. It was only when the lower, underneath leaves turned yellow that a serious problem became clear.

Spreading the plants apart for a slower look, I saw hundreds of insects feasting on the stems and leaves. I took a sample to the Amador Master Gardener’s office and learned that the insect was scales. Scales are so small they are difficult to spot in the beginning. Still, if I had paid attention, looked deeper, taken more interest maybe the scales could have been controllable. Now, there’s a chance scales will infect neighboring potted plants.

Here’s what I found in my Pests of Landscape Trees and Shrubs book on scales:

The newly hatched scale nymphs, called crawlers, emerge and walk along branches or are spread by the wind or inadvertently by people or animals. Scale crawlers are usually pale yellow to orange and about the size of the period. Within 1 to a few days, crawlers settle and insert their strawlike mouthparts to feed on plant juices. After settling, armored scales secrete a waxy covering and remain on the same plant part for the rest of their lives; nymphs of soft scale species can move a little, usually from foliage to bark before leaves drop in the fall.”

Considering how infested the plants were and that scales live on the plant(s) for a lifetime, and can easily spread, I pulled them out and placed them in a tightly sealed bag for the incinerator. Before doing this, I saved a sample to submit to the State of California Pest Prevention Services in Sacramento. Identifying what type of scale may help eliminate or control any future spread of this insect.

For information on how you can submit samples troubled with disease or insects to the California Pest Prevention Services, call 1-919-262-1100. Forms and submission information is not available online. However, their website is worth viewing.

If you have an insect from the United States or Canada, and want it identified, you can upload images at (If you misplace the web address, you can find it here, under Helpful Resources.) This is an amazing sight, from which the family can benefit.

Your local master gardeners can also help identify insects and disease, and offer possible solutions.

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