Sunday, November 04, 2012

Wax, feces, dish detergent, and a baby scale

My Schefflera was harbouring scale bugs again. I had cleaned them off in January and the plant did fine all year, but now that the heater comes on occasionally, and the light is lower, here they are back again.

This time I didn't wait until the leaves were falling off. (Well, one or two did.) When I saw the plant shiny and sticky with leaked sap, I checked, and found the scales.

This time, I removed the plant immediately to the shower, where I sprayed it well with household cleaner, then washed that off with a strong, lukewarm shower. Then I drizzled the whole plant well with dishwashing detergent and left it to soak. After about 15 minutes, I showered it again.

When it was dry, I brought it back to the light and inspected it, finding about a dozen scale bugs, which all appeared to be dead when I inspected them under the microscope.

Large scale bug, about 1 to 1.5 mm long, upside down, and apparently dessicated.

They like to settle along the veins of the leaf and on tender parts of the stems.

Scar, where the bug has been washed off, leaving a ring of waxy strings.

The mother scale bugs shelter their eggs and young under their wax and feces coating, even after they have died. How about these? Did the detergent get under those umbrellas? Were there future scales in there? I flipped all that I'd removed entire on their backs and examined them. In one which looked as dead as all the rest, a hint of motion caught my attention. It was a baby, waving four little legs in the air, transparent, short legs, like blond hair with elbows. The only one; all the rest had been washed away.

Last January, I wondered about those "eye" spots, so visible in the top photo. Someone was asking about them on BugGuide, too, and not getting an answer. I wandered off down the web, and found a USDA site dealing with scale bugs. Down through the halls: Scale insects -- soft scales -- to a page with the anatomy of 46 species of scale bugs. Mine turned out to be Coccus hesperidium, the brown scale. On its page, there's a detailed description and a drawing with definitions of the parts. There is no mention of eyes or eye spots.

What there is, in abundance, are pores. Large pores and micro-pores, and double pores. Some excrete wax, some the honeydew that coats the leaves. Two of those could be what looks like eyes. I've left a question at BugGuide about it.

And it seems that this method, a warm, soapy shower and soak, actually works. A lot more fun that scraping lumps off sticky leaves, too. But I'll still need to check for newborns next week. The plant looks fine.

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