Host an Event Volunteer Join Tickets

Support the plant database you love!

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
1 rating

Tuesday - November 18, 2008

From: Los Angeles , CA
Region: California
Topic: Cacti and Succulents
Title: Cochineal bugs on cactus
Answered by: Nan Hampton

QUESTION:

Mr. Smarty plants. I have purple prickly pear cactus that are developing small white flake like spots, mostly where the thorns would be. Why is this happening and how can I cure it?

ANSWER:

Your cactus sounds as if it is infested with cochineal bugs (Dactylopius sp.).  They are small scale insects that feed on the cactus.  They produce fluffy white wax that hides their bodies as they feed on the cactus and protects them from the elements (drying out, in particular) and from predation.  The fluffy wax also serves as a sail or balloon to float on the wind and take the bugs to a new patch of cactus.  The bugs produce carminic acid that also helps protect them from predation, especially from ants. This carminic acid in the bugs has been used by indigenous peoples of southwestern North America, Central America and sub-tropical South America to make a brilliant red dye for centuries, perhaps millennia, to produce beautifully colored textiles. Originally, the cochineal bugs were limited to the New World.  When the European explorers visited and saw the beautiful red cloth of the natives, they took the cochineal bugs back with them and now they occur all over the world.  When a synthetic red dye was produced the demand for cochineal bugs decreased, although they have also been used to help control cactus popuations.  Recently, however, after it was determined that the synthetic red dyes can have adverse health side effects, there has been a renewed  interest in growing cochineal bugs for red dye.  The dye made from the bugs is currently used in cosmetics and as food coloring.  Because of this, controlling cochineal bugs hasn't really been a priority and, therefore, there isn't a lot of information that I have been able to find for controlling them.  However, click here to read what one grower recommends.  If your infestation is small, I suggest scraping them off (carefully, to avoid the sharp cactus spines) and disposing of them.  You might also be able to wash them off with a water under pressure.  Test a small area first to be sure that you don't injure your cactus and gather up and dispose of any of the insects that you wash off the cactus.

Here are a few links to more information about the cochineal bugs:

Gateway to Sedona with a bit the history of the using the bugs for dye.

Wayne's World with excellent photos of the bugs.

You can read instructions for making and using a natural dye from the cochineal in Using the Cochineal Bug and Dying Things Red!!

 

More Cacti and Succulents Questions

Topmost leaves on yucca are brown
June 08, 2009 - I live in the Lansing, Michigan area, in the lower peninsula and have a couple yuccas whose topmost leaves are brown emerging from winter. Do I prune those, or has the plant died? Thank you.
view the full question and answer

Does the tip of the agave contain poison from Denham Spring LA
December 02, 2009 - I bent over to pick something up and got stabbed in the head with the point of a agave plant. It is about 15 years old and I measured the point-it is right at an inch long. My head did bleed and it bu...
view the full question and answer

Crown rot in Agave americana
June 13, 2007 - My Century Plant's leaves get soft toward the base and eventually fall over and I have to cut them off. What causes this?
view the full question and answer

Can non-native Epiphyllum (Orchid Cactus) be grown in Round Rock, Texas?
July 01, 2014 - Can the Epiphyllum (Orchid Cactus) be grown in the Round Rock Texas area or is this area too hot for it?
view the full question and answer

Information about prickly pear cactus for school project
October 19, 2012 - Hello my name is Case Danzeiser. I go to a middle school called Clint Small Middle School in Austin, Texas. We are doing a species study on a native Texas plants and animals. I choose to study the pri...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.