Cactus and Oak Tree Pests: Ancient Sources of Red Dye

Q I just read your prickly pear cactus (Opuntia ficus-nitida) article and wanted to report that I have six such cactus in my front yard. They have been troubled with a sticky white insect pest for several years. It seems like I have tried everything to get rid of it. I have used alcohol, soap suds, Permethrin, Pyrethrin and orange oil. But the pest, which looks like a mealybug, keeps coming back. Last year I trimmed the cactus back to about 4 or 5 feet. But when they started growing again, the pest came back. What can I do to get rid of it?
— Marion Carole Carion, Woodland Hills
After reading this note, I sent her a response indicating that the pest she mentioned was probably cochineal scale. In reply, she wrote, “When I rub the pest with my fingers, my fingers turn red.” This was conclusive proof that her cactus pest was, in fact, cochineal scale. Sticky white clusters of scale insects are remarkably similar to those of mealybugs.
From the time the Spanish arrived in Mexico in the 16th century, until the advent of synthetic dyes in the late 19th century, cochineal scales were the main source of red textile dye in America and Europe.
Spain had a monopoly on the cochineal dye market for about 250 years until scale-laden cactus pads were surreptitiously exported — by the French and Portuguese — to the Caribbean, the Canary Islands and Portugal.
Sessile female scales attach themselves to prickly pear cactus pads, stick their proboscises into the pads, and suck cactus sap for sustenance. In the process, they produce a rich scarlet pigment known as carminic acid. This metabolite is stored in the gut of the female scales, to be used in defending themselves from attacking ants.
Scale eggs are especially rich in carminic acid and the indigenous peoples who still produce traditional cochineal dye are astute in collecting the pregnant scales for maximum dye production.
Prior to the export of cochineal dye from Mexico to Europe, the main source of European red dye was the kermes scale, which had been utilized as a textile dye since biblical times. In the book of Exodus, the materials utilized in construction and furnishing of the desert Tabernacle included tola’at shani, literally translated as “scarlet worm,” since it was thought that the dye used in coloring the Tabernacle tapestries and other fabrics was derived from a worm.
Recent investigations of this subject by Israeli researchers proved that the scarlet worm was in fact a scale insect that feeds on the Mediterranean kermes oak (Quercus coccifera).
However, the scarlet dye produced by the Mexican cactus scale was eight times brighter than that produced by the Mediterranean oak tree scale, and so all red dye used in Europe was soon manufactured from the cactus scale.
The most basic techniques for cochineal scale control are mechanical. Attach a power nozzle to the end of a hose and submit the scales to a strong blast of water. You can also dip a toothbrush or any kind of brush with a long handle into a solution of dish soap or insecticidal soap for the purpose of scrubbing off the scales.
Once soap is applied, hosing is no longer advised since it would wash off the soap. Still, you should continue to make water blasts and apply the soap at regular seven- to 10-day intervals in order to achieve reasonable control.
In winter, spray with Neem oil, an organic product derived from a tropical tree.
Release of mealybug destroyers, a species of lady beetle, is effective as a biological control technique. Mealybug destroyers, which resemble mealybugs in their larval stage, feast on mealybugs and scales, too. Locally, you can acquire mealybug destroyers from Rincon-Vitova Insectaries in Ventura. Other growers of beneficial insects can be located through the Internet.

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