The top picture features our young grapefruit tree before the scale bug infestation. As a result of the infestation we had to remove one badly infested branch, reducing the plant by about one quarter. I think we severely limited the breadth of the scale bug infestation, and hopefully the remainder of the plant will thrive.
The next two pictures show the scale bugs, first on a portion of stem, and second on the underside of the leaves. The scale bug females are attaching to the plant and feeding on the sap. We were able to catch this infestation rather quickly and removed the branch with the majority of the infestation and will continue to monitor it for remaining scale bugs. We can remove a few scale bugs simply by scraping with a fingernail, but removing one badly infested branch removed 95% of the scale bugs.
The smaller black oblong scale bugs are the youngest females, the yellow ones have begun producing a protective waxy coating. You can also see ants in the third picture which have developed a symbiotic relationship with these scale bugs and are harvesting their excrement for its high sugar content.
The reproductive process of these insects varies widely among their various species and is fascinating in its diversity. In some species the males only live a fraction as long as the females, rapidly growing wings, mating and dying all within a matter of a day or two while the females attach to the plant for a significantly longer life. The females sometimes lose their legs once attaching to the plant from lack of use.
Some species of scale bugs have high proportions of their populations which remain hermaphroditic into their adult stages of life. In other species symbiotic ants will actually carry the young scale bugs to new plants to establish new colonies to farm for their sweet excrement.
Humans have used scale bug populations to control unwanted species of plants, harvested their wax for shellac and other species excrete a red substance suitable for use as a dye.
Since we want the grapefruit more than the scale bugs we removed them in this case, but they naturally occur in a wide variety of ecosystems and are all over the Gohn farm, i'm sure. Maybe we'll find a use for them in another situation. Nature, you never cease to amaze me.
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