We apologize, but Mr. Smarty Plants needs some time to catch up after receiving an overwhelming amount of mail. Soon, we hope to be taking new inquiries once more. I’m grateful.
Before, Mr. Smarty Plants responded to a query regarding cholla cactus cochineal bug management (similar to your prickly pears). What Larry and Brigid Larson wrote is as follows: Cochineal feeding can harm the cactus and occasionally result in the host plant’s death. The Cactus Doctor talks about getting rid of cochineal. Their advice is as follows: 1) A hose with a power nozzle attached to the end. 2) It was advised to clean the affected areas with insecticidal soap or unscented dish soap to treat them if the infestation gets out of hand. Neem oil was also mentioned as a possible natural remedy.
In response to another Mr. Smarty Plants query about cochineal bugs on prickly pear cactus, Nan Hampton provided the following response. (As you can see, this is a common query.) It sounds like cochineal bugs are infesting your cactus (Dactylopius sp.). They are cactus-eating small scale insects. They generate fluffy white wax that covers their body as they consume the cactus and shields them from predators as well as the weather (especially drying out). The fluffy wax also acts as a sail or balloon to carry the bugs to a fresh cactus patch in the breeze. The carminic acid that the bugs create aids in shielding them from predators, particularly ants. Indigenous peoples of southwestern North America, Central America, and subtropical South America have been using this bug’s carminic acid for centuries—possibly millennia—to synthesize a vivid red dye that they utilized to create exquisitely colored fabrics. Cochineal bugs were formerly only found in the New World. The cochineal bug spread around the world when European explorers came to a place and saw the stunning red cloth made by the locals. Although they have also been employed to help reduce cactus populations, the need for cochineal bugs decreased when a synthetic red color was created. But recently, there has been a resurgence of interest in cochineal bug cultivation for red dye because it was discovered that synthetic red dyes can have harmful side effects on health. Today, food coloring and cosmetics both employ the bug-derived dye. Because of this, managing cochineal bugs hasn’t really been a top concern, and as a result, I haven’t been able to discover a lot of information on managing them. If you only have a minor infestation, I advise scraping them off (slowly, to avoid the cactus spines) and throwing them away. They might also come off with a water under pressure wash. To ensure that you don’t harm your cactus, test a tiny area first. Then, collect and get rid of any insects that you wash off the cactus.
The University of Arizona Extension also suggests a similar set of remedies in a publication on cactus diseases.
The usage of insecticides was discussed on multiple websites, and Wikipedia included several natural predators: “The population of the bug on its cacti hosts can be lowered by a variety of natural enemies. Insects appear to be the most significant group of predators. Numerous parasitic wasps as well as predatory insects including ladybugs (Coleoptera), different Diptera (like Syrphidae and Chamaemyiidae), lacewings (Neuroptera), and ants (order Hymenoptera) as well as pyralid moths (order Lepidoptera), which kill cacti, have all been identified.”
Here is more information on the intriguing world of the Dactylopius coccus cochineal scale insect and the carmine dye that was highly sought for fabric dyeing in the 15th century.
Should my cactus have white fuzz?
The substance that appears to be cotton fibers is actually a fine wax made by adult cochineal scale insects, and the little black specks may be their nymphs. On cholla (Cylindropuntia spp.) and prickly pear (Opuntia spp.) cactus, it is typical in this region. The white beards that resemble those on other cacti, such as the Peruvian old man (Espostoa lanata) and Peruvian old woman (Espostoa melanostele), are not an insect byproduct but rather typical, healthy changed tissues. Landscape chollas and prickly pears have a white waxy coating produced by cochineal scale that helps shield these actual bugs from predators and insecticides.
I’ve seen prickly pear pads covered in that white fluff almost entirely. Mild infestations, like the ones Doa Ana County Extension Master Gardener Dael Goodman and I saw at in Las Cruces earlier new week, are more typical. In New Mexico, there are multiple native cholla and prickly pear species. There are numerous of them in the Goodmans’ front yard, and we immediately noted that some species were more affected by the cochineal scale than others.
Topical pesticides, especially natural ones like petroleum oils and insecticidal soaps, are unlikely to be effective no matter what time of year it is if the insects are shielded by a white covering. Also, keep in mind that the ultimate goal isn’t to completely eradicate cochineal scale from your garden—partially that’s impossible—but rather to control the populations of insect pests until beneficial insects come to the rescue.
You will be shocked to see a bright red liquid that seems to appear out of nowhere if you squeeze a glob of the white goo that has healthy females hidden inside. Carmine, a natural dye used for millennia to color textiles and create artwork, is produced inside the bodies of cochineal scale insects. Because this carmine component is also utilized in red foods and cosmetics like sausages, lipstick, pie fillings, and vividly colored alcoholic beverages, check product labels for it. Before the firm converted to an artificial dye in 2006, it was used to create the vibrant color of Campari liquor, but a new generation of craft distillers and other producers are increasingly adopting it as a substitute for synthetic red components.
Goodman and I attempted to film the flowing red fluids squeezing the white tufts on her prickly pear pads with a small stick, but we hardly noticed any redness. The female cochineal population may be declining at this time of year, or those specific tufts may be so old that the residents have long since disappeared and have only left that waxy material behind. We’ll give it another go with a fresher sample in the summer.
Six cholla species and seven prickly pear species are covered in Robert DeWitt Ivey’s stunning reference work Flowering Plants of New Mexico. There are five yellow-flowered prickly pears in that group. Identification might be aided by paying close attention to the pad sizes and spine specifics. If you intend to approach closely, make preparations and carry tongs.
At the Agricultural Science Center in Los Lunas, Marisa Thompson, PhD, is the Extension Horticulture Specialist for New Mexico State University.
How can I eradicate mealybugs from cacti?
Mealybugs can be readily removed if you catch them early, before they have a chance to multiply.
Scrape the mealy insect off your cactus by using a q-tip in rubbing alcohol that is 70 percent strength.
To be sure, examine the plant from top to bottom. For a few more days, check the plant daily to make sure no new pests have arrived.
For each mealybug, use a different side of the q-tip because you don’t want to distribute them more than required.
You will need to spray your plant if the mealybugs are more numerous and cannot be removed one by one.
Before you can totally get rid of these pests, you will need to repeat treatment multiple times to destroy them in all stages.
Using a Homemade Dish Soap Spray
Making your own homemade mealybug spray from things you probably already have on hand is another option.
Neem oil, if you can find it, should be added to the combination for a far better success rate.
Your plant will receive a layer of protection from neem oil, making it more difficult for insects to eat through it.
With Blue Dawn dish soap and a 2 percent soap to water ratio, I’ve had the most results.
For instance, my spray bottle holds 650ml (or 20 oz), so I added 13ml (or half an ounce) of dish soap before adding water to cover the remaining space.
Use distilled or bottled water to prevent mealybugs from benefiting from the minerals in your tap water.
You want to make sure you get every area of your cactus since these small creatures can hide in crevices and crannies. Spray this mixture immediately on the surface of your cactus.
If there are still some bugs present, repeat the process again in a few days. To remove any remaining soap, spritz the cactus with distilled water after the bugs have all disappeared but don’t use any soap this time.
Avoid using too much soapy water because dish soap is still a detergent and might harm your houseplant if used excessively.
Use 70% Isopropyl Alcohol
The best method for getting rid of mealybugs on your cactus is typically to kill them using isopropyl alcohol.
Spray every bug and white fuzz spot you notice with 70% isopropyl alcohol (often referred to as rubbing alcohol) with a spray bottle.
Avoid using alcohol that is 90% strength since it will flash off too rapidly and not be as effective.
And if you opt for this strategy, be careful to keep your plant away from hot or direct sunlight to prevent burning. Spray ideally in the morning or at night.
The mealybugs are almost instantly killed by the isopropyl alcohol, which almost dries them up on touch. This will only work if you spray every single bug you see, just as the soap water method.
However, be careful with the alcohol; too much of it can harm the plant.
It might be better to dip a q-tip in the isopropyl alcohol and kill the mealybugs one at a time if you have caught them early and are certain that there are only a few bugs.
Nowadays, it can be challenging to get isopropyl alcohol, so if you can’t, try the dish soap and neem oil method first.
As there are probably other components in hand sanitizer that could be detrimental to your plant, I wouldn’t advise using it to get rid of mealybugs.
Systemic Insecticide Spray
Finally, you can buy systemic pesticide (bonide granules) at your neighborhood garden center or greenhouse to eradicate mealybugs from the inside out. Mealybugs become poisoned by the fluids.
In essence, you’ll water your cactus while using the pesticide, which works more like an antibiotic than a topical application like the other two techniques.
I advise applying a spray (either the soap mixture or rubbing alcohol) together with the systemic pesticide to get rid of mealybugs permanently.
This is because mealybugs may still be present in your soil, making it preferable to attack them from all sides.
Ideally, repot your plant in fresh soil if you can to ensure that no bugs or eggs are still present.
Other Methods That Might Get Rid of Mealybugs
You might try taking the natural approach and introducing other bugs that will devour the mealybugs if you have mealy bugs on your outdoor cacti.
Ladybugs will devour them, and mealybugs and aphids are both consumed by the larvae of the Green Lacewing.
To eliminate bugs, larvae, and other pathogens, some people bake their soil in the oven.
You can sterilize a small amount of soil by putting it on a baking sheet and roasting it in the oven for roughly 45 minutes at 175200 degrees Fahrenheit.