Question

sticky leaves   QUESTION: Hello Jack,

Thanks for answering my question about my new bought orchid. You are right the problem might cause by the wet root. I had that problem since I watered it. Now I stop watering and keep it in a place with good air flow. It looks better now.

I have another question today. I have an orange indoor plant which I grow from a seed three years ago. This year, I noticed that the leaves have oil on the top and bottom surfaces and very sticky. I also found something on the leaves and stems as you can see in the attached picture. I used paper towel to remove it but it kept coming back. Would you please help me identify it and tell me what I should do to keep my plant healthy and clean?

Thanks you in advance.

ANSWER: Lena,

Excellent picture. These are called scale insects and they are related to aphids. Like aphids they excrete a sweet, sticky material called honeydew which is made of plant sap. Scale insects can damage plants in the same way that aphids do as well (wilting, growth deformities, even death).

One treatment is insecticidal soap but it must be repeated once a week or so until the scales are gone which can take awhile. Systemic insecticides are another option but these are a lot more hazardous.

Here's an article about scale insects http://www.livingwithbugs.com/sca_ins.html (yours is a different species) for some background.

Here's an article about insecticidal soap http://www.livingwithbugs.com/insecticidal_soap.html if you are not familiar with this material.

Post a follow up if you have questions.

Jack DeAngelis
http://www.livingwithbugs.com



---------- FOLLOW-UP ----------

QUESTION: Hi Jack,

Thanks for the information. Are scale insects animals? I never seen anything moving on my plant. Will it infect my other plants like orchids?
Do I have to use commercial insecticidal soap to cure it? I am currently using some dish detergent plus some hydrogen peroxide solution plus water to clean it. Any chance to cure with my solution?

Last question, what caused it?

Thanks

Answer
Lena,

Yes, scale insects are insects but as adults they don't move around. Once they find a suitable spot to feed they settle down and stay. Scale insects can infest a variety of houseplants but they tend to develop slowly so if you are vigilant you can stay ahead of the problem. Insecticidal soap is better than dish soap because it is purer and less likely to harm your plants. I'd be very cautious about using anything like hydrogen peroxide because it could do more harm than good. Scale insects are very common pests especially on plants that have been growing in the same place for a long time. Good luck.

Jack DeAngelis