From the Digest

Bugs (and More)

Mealybugs are difficult to remove from the hooked spines of this mammillaria, even when the bugs are dead.

By Mike Hellmann (January 2020)

This is not just an article on how to get rid of bugs that are on your plants. It is meant to help us address “bug” issues with a more holistic strategy to prevent, identify early and deal with what is looking to damage your plants long before the damage is done. I chose the term “bugs,” as I think it best collectively covers all the crawling nemeses we encounter while growing our plants.

Bugs are omnipresent and very opportunistic. They will always be here as long as they have a food source. Just like crabgrass and other weeds in the yard, open field or vegetable garden, they make their presence known and always will. Even if thought to be under control, it doesn’t take long for them to again get the upper hand. They can be suppressed, but not eliminated.

To be environmentally responsible and truly successful at bug control, it really falls on us to prevent rather than cure bug problems. In the horticulture industry, the concept of IPM (Integrated Pest Management) was embraced long ago. It encourages a proactive, preventative, safe and responsible means by which to keep plants (relatively) bug-free. Prevention, early detection and removal are much more advantageous than waiting until a big pest population rears its head before acting.

When is the best time to pull a weed? Is it when small and not yet spreading/setting seed or when looming big/tall and obnoxious after seed has dispersed into the wind? Yes, the best time to pull a weed is when it’s small. The same logic applies to bugs.

With all bugs, the best defense is to grow strong, healthy plants. All pests are opportunistic and will gravitate toward plants that are ailing or compromised, as their defense mechanisms are weakened. Thus, cultivation efforts regarding proper soil, light, exposure, irrigation and fertilizer combine to put up the biggest roadblock against the nasty critters.

That being said, monitoring for bugs is also very important. More important than just monitoring is to monitor routinely. Inspect the newest growth, under leaves and the leaves themselves for signs of pests or discoloration that may indicate their presence. Quite often this means looking for symptoms of bug populations rather than the bugs themselves.

Bugs are quiet. They move slowly while keeping a low profile. Kind of like moles in the yard, they’re “sneaky.” But once established, their populations can explode.

Unless we’re dealing with swarms of locusts, large bug populations usually don’t “just happen.” They’re the results of an initial bug population … and time. If we let our guard down, time is on their side. This is where we often fall short. We get complacent for many reasons. Complacency is not good.

When you acquire new plants, inspect them immediately for pests and try to quickly repot into your own soil mix, which will help the plants acclimate to your growing regimen. We usually inspect plants we purchase, but perhaps not always. Sometimes we are gifted plants and need to heed this same caution. I know I have often regretted not following through with both of these simple procedures.

Early detection and action are key to pest control. Using that weed analogy, when you pull a weed at a small size, you can totally eradicate it. When you let it go, you risk it going to seed, which can happen quickly. Bugs are the same. They procreate exponentially, especially during the warm growing season. This then makes control much more difficult.

When detected early, controls can include physical removal, as well as simple, safe sprays and treatments that are not that toxic. The best time to closely pay attention to your plants is when you water. Take your time and look for anything different or out of the ordinary. Watch for ants, as well. They are attracted to the secretions left by aphids, scale and mealybugs.

What do we do when we find bugs on our plants? Below are a few quick fixes for some of the more common pests – if they are caught before they reach epidemic proportions.

This astrophytum shows the sooty mold (top center) that makes mealybug infestations even worse – fungi that feed on their sugary excrement.


Mealybugs are easily controlled (if detected early) by dabbing or spraying with a 50/50 mix of alcohol and water. Be sure to focus on leaf nodes and where new branches separate, as mealybugs are elusive creatures. They often hide and lay eggs where sprays and Q-tips do not reach.

On larger plants or where a severe infestation develops, some kind of systemic option may be better. This will translocate into the vascular system of the plants and kill pests no matter how well they hide. Remember that all insects and mites have a life cycle that includes egg, larva, pupa (four-stage life cycle only) and adult, so no matter what you use, it will only affect the exposed or actively feeding stage of the pests.

With mealybugs, you also have the root mealy part of the group, which can be difficult to detect without inspecting plant roots. Here, the symptoms are often evident as discolored or atypical top growth.

Cacti and the asclepiads seem to be the most susceptible to root mealies. The best control may be some kind of systemic chemical used as a preventative or, when necessary, as a treatment. Various oils and insecticidal soaps are used on many houseplants and outdoor ornamentals but should not be used on succulents without testing first. They can permanently scar some succulents, especially if exposed to sun or stressed at the time of application.

Spider mites are only about one-eighth of an inch long. They fall under the Arachnid family because they have eight legs. Photo from

Spider Mites

Spider mites are humbling creatures that are probably the most difficult to both detect and control. To make matters worse, they are almost invisible to the human eye. Often, the only symptom may be the discoloration of foliage, which happens long after a population establishes itself. This is the result of the mites feeding on chlorophyll, the green pigment of plants. This leaves behind a faded leaf color and contorted foliage.

Spider mites love the new, tender growth of many succulents – mesembs in general and almost all tropical plants. They tend to be most prevalent in winter, as they love the dry indoor air of our homes. The mites find these conditions very inviting, for they work well with the mites’ physiology and ability to secrete wastes.

Fortunately, outdoors they are not as comfortable due to the higher humidity and frequent rains. They can thus be discouraged by overhead watering and topical sprays – even if just with water. When I had a larger collection of tropical plants such as alocasias and anthuriums, I took them to the shower stall (during winter months only) every weekend and gave them a warm, gentle, five-minute shower. This worked wonders. Nothing had a chance to establish a significant population. Oh yeah, do not forget to rinse out the tub afterwards!

Systemics don’t work well on mites. They are shallow feeders that don’t reach the deeper vascular systems of plants, where the chemical is waiting.

Mites can be very challenging to detect. Tiny critters and very fine webs often are the first indicators of a population. Many confuse these webs with those of common garden spiders. To help find spider mites, some place a white sheet of paper under a plant while shaking the foliage or brushing the stems. Here the mites are much more visible.

About the same size as spider mites, aphids are another hard-to-spot pest. Photo from


By comparison, aphids are relatively easy to detect and control. Bubbly and green, yellow or orange in color, they are hard to miss. Physical removal is often enough. Otherwise, just about any over-the-counter product will ruin their day.

A few succulents attract aphids, such as adenias and adeniums. Others that put out vinelike stems seem to be quite popular with aphids. Again, these aren’t the worst of our nemeses, but one that needs to be on your radar.


Squirrels are a pest category I cannot help you with without incriminating myself. You’re on your own.

They are much easier to detect than other pests, but not easy to eradicate from our property. They seem to be the most problematic when summers are dry, and they are looking for moisture. Then your sempervivums and any other soft, succulent, unarmed plant leaf or body is fair game.

I guess it is hard to blame the little rascals. They also have a real affinity to Portulacaria afra. If you come up with an effective, nonviolent means of control, please let me know. It seems once they detect a food source – be it your plants or a bird feeder – they will never forget it.

In summary, it is best to prevent and be proactive with pests. It is so easy to be complacent, especially if you are taking care of hundreds of plants or if you’ve never yet experienced a pest problem.

When you need to treat your plants with any kind of spray, make sure your plants are well hydrated, out of the sun and completely without stress. Otherwise, phytotoxic results may develop. Burning of plant tissue often occurs if you spray the wrong thing on the wrong plant at the wrong time.

In addition to the above, please take time to read the label of any chemical that you apply. It has a lot of information of which you should be aware before using. Also, many succulents don’t take well to horticultural oils (including neem oil) or insecticidal soaps that are commonly used on tropical plants. This is not to say that these cannot be used in some situations, but use all the above cautions before you do.

If you are up against a pest situation, please remember that you have resources in this society that can help you through it. Chances are we have experienced the exact same thing ourselves.