White bugs on cactus

A cactus might not look like the friendliest place to make your home, but some pests love making a new home on a cactus. While cacti are extremely easy to grow because they require little to no water, they do require attention from time to time in order to keep them healthy and safe.

Lots of different pests can inhabit a cactus. Here are some DIY pest control tips that can keep your cacti healthy and pest-free:


Identification: Mealybugs leave a white fuzz on your cactus, which is an easy way to know that you have a bug problem. Once they are fully grown, mealybugs look like tiny crabs. These bugs multiply quickly, so take quick action. One female can lay 600 eggs!

Prevention: Just like killing a spider, these small bugs can be killed by hand simply by crushing them. If you’re more of a hands-off bug killer, you can dab a mealybug with rubbing alcohol or spray it with a mixture of liquid dish soap and water. After applying the soap, let it sit for a day and then gently rinse that area of the cactus.


Identification: Mice and rats are always looking to upgrade their home. Some Arizona homeowners have been surprised by rodents who eat through the bottom of an outdoor cactus and will hide or even try to live inside of it!

Prevention: You can wrap the bottom of your cactus in wire mesh, but that isn’t always the most visually appealing option. If you know mice are eating your cactus you can set out traps, or even buy small bags that smell like pine. Rodents hate the smell of Christmas trees!

Rodents such as mice and rats can cause your family harm. Check out our rodent control—including treatments for roof rats!

Work With Defense


Identification: If spider mites are making your cactus their home, you will see yellow and rust-colored spots staining your plant. These critters are exceptionally small – you might not even be able to see them until after they’ve damaged your plant.

Prevention: Spider mites like to move from plant to plant, so by the time they are detected they might already be living on nearby cacti or other plants. Prevention is key to controlling spider mites. Once they move in, they’re exceptionally hard to get rid of.

We recommend buying a pesticide that specifically says on the label that it controls spider mites. Ladybugs are also exceptional at naturally controlling spider mites outdoors.


Identification: Scale are small tan or brown bugs that like to eat sap. They look like very tiny bubbles. After they are done eating away at an area, you will be able to see a large scar on the cactus. A female can lay three hundred eggs at once, so a lot of damage can be done in a short amount of time.

Prevention: When you find scale on your cactus, remove them with your fingers or a pair of tweezers. If your cactus is strong enough you can spray it with a garden hose to get them off, but keep in mind that they’ll just come back.

To help keep scale off your cactus, feed the roots an insecticide during the growing season. This will prevent scale from invading your plants.


Identification: Ants don’t directly harm your cactus, but they will be attracted to it and can even carry mealybugs and spider mites.

Prevention: Spraying lemon juice around your cactus will help keep ants away. You can also use insecticides that repel ants.

Ants causing you problems? Our comprehensive pest control solutions cover ant control—no additional packages needed!

Get a Free Quote Now


We all know the scenes in cartoons where a character falls on a cactus and shoots into the air. That might be a funny exaggeration, but cacti do injure people every year.
If you’re concerned about the health of your cacti and other outdoor plants, but the thought of pests in your cacti and other plants gives you a prickly feeling – turn to a professional!

This blog was written by Ryan Michel, Owner of Defense Pest Control

Learn more about how Defense Pest Control can keep pests out of your cacti and the rest of your yard!

Cacti and succulents have to be resilient to survive in some of the hottest and driest places on earth. Little gets past their sharp spines and tough skin, except two tiny insects that can do a lot of damage.

Mealybugs and scale are particularly attracted to cacti and succulents. They can injure and even kill them by feeding on their juice.

Mealybugs attack all parts of a plant, above and below ground, but are usually found on leaves and stems. A plant will be covered with what looks like sticky white cotton, and up close, you can see small, white oval bugs.

Mealybugs can be tough to completely eradicate. Scale insects cover themselves with hard oval, tan or brown shells. They congregate on leaves and stems, and multiply quickly.

Treat Cacti and Succulents for Mealybugs and Scale:

  • Wear gloves before handling cacti, or use bunched-up newspaper or paper towels to hold the plant.
  • Spray water hard enough to dislodge the insects, but not so hard as to damage the plant.
  • Nick scale off with a fingernail or tweezers.
  • Spray the plant with insecticidal soap, neem oil or horticultural oil. Follow directions on the package, as improper use can damage the plant.
  • Wipe mealybugs or scale with a cotton swab dipped in a solution of 50 percent rubbing alcohol and 50 percent water.
  • Large infestations may need treatment with a systemic insecticide. This is a last resort. Avoid insecticides containing imidacloprid, which can harm pollinators. Consider whether to remove and replace the plant instead.

Product Checklist:

  • Gardening gloves
  • Newspaper or paper towels
  • Garden hose with sprayer
  • Tweezers
  • Insecticidal soap
  • Neem or horticultural oil
  • Rubbing alcohol
  • Cotton swabs
  • Systemic insecticide

White Spots on Cactus – Knowledgebase Question

First of all, congratulations on making your cactus happy enough to bloom! The white patches may be a fungus, brought about by less than perfect growing conditions, or they may be evidence that your plant has an infestation of mealy bugs. Since your cactus bloomed earlier in the year, it’s probably happy in its environment. Try looking at the patches with a magnifying glass to see if you can tell whether the patch is a collection of little insects with cottony coatings, or just a single blotch of hairy fungus. Mealy bugs can be very difficult to control, and the first course of action is to try to remove them with a cotton swab dipped in plain water or rubbing alcohol. Or, try prying them off with a blunt knife. (You won’t do any more damage to your plant than the insects are already doing.) This may leave scars that will callous over, but it will help you save your plant. As a last resort, you may have to use an insecticide to rid your cactus of the pests. Mealy bugs travel very slowly, but they can leave eggs on all kinds of surfaces. Move your cactus away from other plants, and be sure to wipe down the sides of the pots to get rid of any eggs.

Cacti and Succulents

Many genera and species

Cactus Anthracnose (fungus – Colletotrichum (Gleosporium) spp.): This disease affects several kinds of cacti, Cereus, Echinocactus, Mammillaria, and particularly Opuntia (prickly pear). Infection results in a rather moist light brown rot which shows many light pink pustules on the surface. Spots are small at first, later enlarge and become covered by the small spore-producing pustules. Large areas may be affected, sometimes destroying entire plants. No satisfactory control is available, other than removing and destroying diseased cladodes as soon as noticed. In the greenhouse, soil from infected plants should be removed and benches disinfected. Spraying with a copper fungicide may help in checking the disease.

Charcoal Spot (fungus – Stevensea (Diplotheca) wrightii): Charcoal spot is a common and destructive disease of Opuntia in Texas. Small spots, usually one-fourth inches or more in diameter, appear first. The spots are surrounded by a ring of small raised dots that are the fruiting structures. Spots later enlarge, but remain separated. There is no control for infected plants. Remove and destroy diseased specimens.

Dry Rot (fungi – Phyllosticta concava and Mycosphaerella spp.): Small black circular spots develop first, which later increase in size until they reach a diameter of one or two inches. Further advance is checked by the development of callus tissue. Minute fruiting structures are seen in the infected tissue. The disease is in part physiological, influenced chiefly by soil moisture. Remove and destroy diseased specimens.

Scorch or Sunscald (fungus – Hendersonia opuntiae): This disease is common and serious on prickly pear cactus (Opuntia). Spots at first are distinctly zoned, later enlarging until entire cladodes turn a reddish-brown and finally die. The center of the disease area is grayish-brown and cracked. Other fungi may also be present in the diseased area. No practical control has been developed.

Cotton Root Rot (fungus – Phymatotrichum omnivorum): Several members of the cactus family are susceptible to attack by the cotton root rot fungus. Infected plants die. When pulled from the soil the brown strands of the fungus can be found growing on the root surface. No control practice is available. For additional information, see the section on Cotton Root Rot.

Soft Rot (bacterium – Erwinia carotovora): The bacterium enters tissue through natural openings and wounds. Under conditions of high humidity, the bacteria reproduce quickly, spreading to healthy parts of the plant. Diseased tissue is watery, soft, black and deteriorates rapidly. If environmental conditions turn dry, the development of the disease may be checked. The best control is to avoid wounds, treat broken surfaces right away with a copper fungicide and avoid having plants in places where humidity is high.

Nematodes (Meloidogyne spp.): Most of the cacti and succulents are susceptible to infection by root knot nematodes. Infected roots show small galls which are typical of the disease and serve to identify it when clean, washed roots are observed. Fumigate or sterilize soil before potting. for additional information, see the section on Root Knot.

Other Diseases (fungi): Other fungi known to cause disease on cacti are Fusarium oxysporum (Fusarium rot), Macrophomina phaseolina (Charcoal rot), Septoria spp., Helminthosporium cactivorum, and Aspergillus alliaceus (Stem and branch rot).

Scab (physiological): Particularly common on prickly pear cactus. Rusty colored, corky areas appear on the stems. Scab is thought to be a form of edema, resulting from overwatering and poor ventilation. Increase light and decrease humidity for control.

Stem Rot of Cacti (fungus – Drechslera cactivorum): Basal or top rot of seedling cacti that turns cactus into a shrunken mummy covered with brown spores. First symptoms are yellow spots. It can completely rot a plant in four days. The fungicide Captan should give some control.

By Susan Campbell

We all love color in nature, especially this time of the year, but none are as vibrant as the color red. “Since the beginning of history the color red has appealed to societies as a color meaning danger and courage, revolution and war, violence and sin, desire and passion.” (1) No red dye was as vibrant in 1519 when Spanish conquistadors found the Aztecs selling an extraordinary red dye in the great market places of Mexico. They called it grana cochinilla or cochineal.

“When Cortes invaded, he was amazed to find Montezuma and other nobles dressed in robes dyed a brilliant, vivid red. He was also amazed to see the native women’s hands and breasts painted the same intense color. In Tenochtitlan (now Mexico City) he found bags of dried cochineal sent as tribute to Montezuma, which were promptly shipped back to Spain. The dye was so much brighter than the rest and almost instantly in high demand in Europe. By 1600, cochineal was second only to silver as the most valuable import from Mexico.” (2)

Cochineal is a scale insect and is found on prickly pear cactus, Opuntia engelmanii. As a rasping, sucking insect, it feeds on the tasty juices of the cactus. It produces a cottony white covering to protect itself from predators. Once plucked from the cactus, the insect is dried and dehydrated, then shipped to all parts of the world to be used in all sorts of ways. Dried cochineal is used in textile dying (such as wool), cosmetics, food coloring, and artist’s paint. Today it is also used as a red dye in nutritional drinks. One of the most famous uses for cochineal was to dye the jackets of the British military “Redcoats” during the Revolutionary War.

Cochineal Scale On Cactus – How To Treat Cochineal Scale Bugs

If you have prickly pear or cholla cacti in your landscape, you’ve probably been confronted with a cottony white mass on the surface of the plants. If you were to remove the mass and crush it on a piece of paper, the result would be a smear of vibrant red, a tell-tale sign of the presence of cochineal scale bugs. What is a cochineal scale and how can you treat cochineal scale? Let’s learn more.

What is Cochineal Scale?

Cochineal scale (Dactylopious spp.) bugs are commonly found on cactus of the Opuntia genera of cacti. It is an insect native to the New World, which was used by the Aztecs for dying and painting. Spanish conquistadors took dried cochineal scale powder back to their homeland where it became a sought after red dye until the 1850’s. Cochineal dye was replaced in popularity by aniline dyes but is still commercially produced in Mexico and India where it is still used to color food, drinks, cosmetics and paints.

Cochineal Scale on Cactus

These small insects suck on cacti leaves. Cochineal scale on cactus is initially a nuisance but, in extreme infestations, can weaken and kill the plant. The cottony, waxy mass is produced to shelter the female insects and their eggs. When the eggs hatch, the nymphs feed on the plant for three weeks, moving all around the plant. After their three weeks of feeding, the nymphs settle down to spin the cottony mass that shelters them from predators.

How to Treat Cochineal Scale

If the infestation of scale is minimal, cochineal scale treatment consists simply of a spray of water. Blast the affected area with hose under pressure. This will expose and weaken the scale bugs, which can then be treated with an insecticidal soap or a mix of ½ teaspoon of dish soap to a gallon of water. If the problem persists, prune off the worst pads at the joints and discard them.

If the cactus seems to be heavily infested, you may have to go with a chemical cochineal scale treatment. Apply a combination of insecticide, dormant oil spray and/or insecticidal soap. Malathion and triazide combined with Neem oil or Volck dormant oil spray should do the trick.

Apply according to the manufacturer’s directions. Do not spray on hot, sunny days, as the plant is likely to burn from the dormant oil. If the weather is too hot to use dormant oil, use pesticide mixed with dish soap.

Cochineal scale is spread around by sticking to birds’ feet, so you need to inspect the plant frequently. Spray the cactus well, paying attention to joints. Spray again in 7 days and then again 14 days after the first application. You’ll know if the scale is being killed off when the white cottony tufts turn gray and squeezing them doesn’t result in a red smear. If scale is still alive after 14-30 days, reapply as above.

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

Search Smarty Plants

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.

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

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? 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!!

Need advice about an agave that didn’t survive the winter in Myrtle Beach, NC.
March 09, 2011 – I live in Myrtle Beach, S.C. bought an agave big last summer and it died in the winter. Some green is showing on the bottom should I cut it all down because the whole top is dead. Thank you
view the full question and answer

Transplanting blue agave pups in Arizona
February 03, 2009 – I have a blue Agave with lots of pups, how do I transplant a few pups into planters. What kind of soil and how much water will they need?
view the full question and answer

Is Sedum recommended for a greenroof project in Houston
July 23, 2008 – Would you recommend using Sedum for a green roof project in Houston, Texas? Will the humidity effect the sedum? If sedum would be a poor choice, what would you recommend for Houston?
view the full question and answer

Century plant dying after bloom
April 06, 2006 – Help!! I want to save my Century Plant from dying. I have already lost one and I don’t want to lose this one. Can cutting the stalk before it gets too big save this beautiful plant? Please, pleas…
view the full question and answer

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

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

A: 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.

Another discovery

It seems just about every time I step into Armstrong Garden Center in Valley Village, near the corner of Magnolia Boulevard and Coldwater Canyon Avenue, I encounter plants I have never seen before.

Just the other day, I came upon a new hybrid called Echibeckia ‘Summerina Brown.’ This robust perennial has Echinacea, the famous medicinal plant, and Rudbeckia, or black-eyed Susan, for parents. Rudbeckia is a plant that blooms orange all summer long. Echinacea, with droopy mauve petals surrounding very fat yellow centers, is more challenging to grow in our area than Rudbeckia, but will succeed in half-day sun where soil is fast-draining. Thus Echibeckia would probably do well in any location with at least four hours of direct sun.

Crown of thorns

The moniker “thornless crown of thorns” (Euphorbia geroldii), a smart marketing ploy, exploits the generic affiliation of this plant with true crown of thorns (Euphorbia millii), a plant whose red bracts are produced throughout the year.

I do not have personal experience with the thornless crown of thorns, but if its bracts on display are even half as long as those of its thorny namesake, it would definitely be worthwhile to have around, especially since you don’t have to worry about being stuck by thorns.


Annual celosia is famous for its plumed or cockscomb shaped inflorescences in red, pink or gold. A new cultivar (Celosia argentea ‘Intenz’) has elongated white and pink cones that cover the plant, according to its label, from now until fall. Celosia is not as water-needy as most people think. Mulch the soil well and you should not have to soak your celosia more than twice a week during the summer.

For more information about area plants and gardens, go to Joshua Siskin’s website at www.thesmartergardener.com.. Send questions and photos to [email protected]

Leave a Reply

Your email address will not be published. Required fields are marked *