B)    Parasitic insects.

What’s That White Stuff On My Cactus?

The “green” approach to native desert landscaping in our yards helps the local ecology of our area. By choosing species native to arid environments, in particular, species native to our local desert, we contribute to the overall health and survival of our fragile ecosystem.  As we choose to replace natural habitat with development, it is also important to encourage species-friendly stops in an otherwise fragmented corridor of native resources that generations of wildlife have come to rely on. It is a wildlife watchers reward to landscape with native plants that will attract local and migrating wildlife. Because we are encroaching on wild habitats, we must also act responsibly for wildlife that may be considered threatening or damaging that will also be attracted to desert landscapes.

 Photo: Charles A. Washburn       

                                                                             One common and fairly harmless species is the cochineal scale (Dactylopius coccus), an insect that

                                                                             frequently appears on opuntia spp. of cactus, like the prickly pear. Close inspection of these pests reveal a waxy-cottony substance covering female cochineal and their nymphs. The insects secrete this substance as protection from the sun and to prevent dessication while feeding on the host cactus. The bodies of these insects produce a crimson red pigment that makes their uncovered bodies look dark purple—the source of a highly exported product with its origins beginning in pre-Hispanic Mexico. Used by the ancient Aztec and Maya cultures, cochineal dye of the past was later desired by the Spaniards for its vibrant color and during colonial times was exported to Europe, through Spain . Cochineal dye became colonial Spain ’s 3^rd most lucrative income, behind gold and silver, until artificial dyes replaced the demand.

Today, the cochineal insect is still farmed for its carminic acid in Mexico as well as Peru , Chile , and the Canary Islands . It is a source of natural dye replacing artificial methods particularly important in the food and cosmetic industries, as well as a still popular fabric dye. Look for cochineal in food and cosmetic ingredient labels under: carminic (kermesic) acid, carmine, or E120.

That’s interesting, how do I get rid of it?

A strong water blast strips these insects off of your cactus and will keep them from damaging your plant further. 

*  *  *  *  * 

What’s that white stuff on my cactus? excerpted from 2004 Caliso Learning The Prickly Native: Native Americans and the Cactus program including the following internet sources:

Carmine (Cochineal and Kermes), retrieved from “http://www.newton.dep.anl.gov/natbltn/200-299/nb203.htm”

Red Scales in the Sunset, retrieved from “http://www.botgard.ucla.edu/html/botanytextbooks/economicbotany/Cochineal/”

Cochineal, Wikipedia retrieved from "http://en.wikipedia.org/wiki/Cochineal"