All about mealybugs, cacti and succulents
Mealybugs are small creatures that, like us, love cacti and succulents. We often get questions about them: how can you actually recognize them? Are they really mealybugs, or just a bit of fluff or a piece of perlite? Since these little creatures often appear on cacti and succulents, we’ve written a fun and informative blog about them. That way, you’ll learn exactly how to identify mealybugs and how best to treat your plants.
What is a mealybug?
A mealybug is a small insect that feeds on the sap from your cactus or succulent. They are oval-shaped and grayish-white. Young mealybugs are 1 mm long, while adult females can grow up to 5 mm and may have many woolly filaments around them. The males are smaller than the females and develop wings. They use these to fertilize many females. The females change very little as they pass through the different stages. They simply grow larger, and their mobility changes.
When the eggs hatch, the young mealybugs are also called crawlers. This is because they can move quickly across the plant. They look for a good place to hide and eventually settle. At this stage, they do not yet suck sap from the plant.
The next stage is the nymph stage. The mealybugs have grown larger and begin feeding on plant sap. They can still move at this stage, but very slowly. After this, they develop into adult mealybugs. The male has no mouth and cannot feed. For this reason, he searches for females to reproduce. Female mealybugs make a woolly nest around themselves. They lay their eggs in it, after which they die. And so the cycle begins again. Under ideal conditions, the eggs hatch after 6–8 days.
What damage do mealybugs cause to plants?
Mealybugs suck the nutrient-rich sap from the plant. This slows its growth. For example, you may see oddly shaped leaves, yellowing on the leaves, or a yellowing cactus tip. Photosynthesis in the plant also decreases. This weakens your plant and makes it more susceptible to the next problem.
Plant sap contains a lot of sugar and very little protein. Mealybugs need a lot of protein, so they consume a large amount of plant sap. They excrete the excess sugar as honeydew. This provides a good breeding ground for fungi (both beneficial and harmful). Since the plant’s resistance is weaker, this can damage it.
How do plants get mealybugs?
There can be many different causes. Sometimes you suddenly find them on plants you’ve had for years, but they can just as easily appear on plants you’ve only had for a few months. We’ve listed the most common causes below.
- Mealybugs can reach your plants on air currents coming in from outside.
- They can hitch a ride on your clothes if you’ve come into contact with another plant that has them.
- Male mealybugs can fly. They can simply fly in through an open window or door and settle on your plant.
- They can arrive on new plants and then spread to other plants.
The causes listed above are the most common ones. There are probably others that occur only occasionally. Do you have lots of plants together, for example in a greenhouse or on your windowsill? And do you see lots of ants walking around the pots? Then you may want to check for mealybugs more carefully. Ants love the sweet substance mealybugs excrete. They protect mealybugs from predators, often by grouping them together to make this easier. This also helps mealybugs spread from one plant to another.
Should I inspect my plants every day, and how do I recognize mealybugs?
Based on the above, it might seem impossible to keep mealybugs away. In practice, it’s often not that bad. I certainly wouldn’t start inspecting your plants obsessively every day. You can do this every few weeks instead. What’s more important is knowing where to look and what they look like. Mealybugs are small, oval-shaped creatures measuring 1–5 mm. Young mealybugs do not yet have a woolly coating, while older adult females do; their wool is white. Mealybugs like to settle in places you can’t see right away. In almost all cases, they appear in the same spots on your cactus or succulent. We’ve listed them below:
- On leafy succulents, they are usually found on the underside of leaves or in the leaf axils (the area where the leaf joins the plant).
- On cacti, they hide among the spines at the top of the plant or often between the ribs. Young mealybugs in particular can hide well here.
- Always check 1–2 cm above the soil line where your cactus or succulent emerges from the soil. They can hide well here, and this is an area where they can easily suck sap from the plant.
- Spent cactus flowers. For some reason, they seem to prefer these, especially larger flowers. Once the flowers have finished blooming, they can remain on the plant for a while. Once they dry out, you can often remove them from the plant. If you’re waiting for the seed pod to ripen so you can collect seeds, be sure to check it carefully.
- Some species, such as Aeonium and carrion flowers like Huernia and Orbea, are especially susceptible to mealybugs. Given the choice, mealybugs will always choose these plants. Check these species more often.
- Some cactus and succulent species have features that closely resemble mealybugs in shape and color. Think of the spots on an Astrophytum, or the white areoles of various Mammillaria or Opuntia species. Also, the scale-like leaves of an Avonia. These plants are not more susceptible to mealybugs, but you should inspect them extra carefully because mealybugs can hide very easily among these features.
- Check plants with low resistance more carefully. Plants that are not doing well are more susceptible to mealybug infestations.
The points above are particularly helpful for spotting an early mealybug infestation. This makes it quick and easy to treat. As an infestation grows, you’ll naturally see them in different places all over the plant. But at the beginning, when there are only one or a few, they almost always choose one of the spots listed above.
What can I do about mealybugs?
Fortunately, there are many things you can do about mealybugs. If you find a plant with mealybugs, we recommend keeping it separate from your other plants at first. This will prevent them from spreading further. The treatment depends on the size of the infestation. Below, we describe a few household remedies, biological control using natural predators, and an organic pesticide that we’ve had very good results with ourselves. Chemical pesticides are not covered. They are often harmful to the environment and many other living organisms besides mealybugs. The choice to use these products is up to you; we do not want to promote them.
If you’ve found one or a few mealybugs on your plant, you can dab them with a small brush or cotton swab dipped in rubbing alcohol. Mealybugs cannot tolerate this.
If there are several, or you’re worried you may have missed some, you can also spray the plant with a mixture of water, liquid green soap, and rubbing alcohol. Ratio: 500 ml water, 10 ml green soap, and 10 ml rubbing alcohol. For succulents with a waxy coating, test it on a single leaf first and check that it does not cause discoloration or damage the protective wax layer.
These household treatments work well. Keep an eye on the plants for 2 weeks to see if any new mealybugs hatch from the eggs, and treat again if necessary. Under ideal conditions, the eggs hatch after 6–8 days. If it’s a little colder, this may take longer. For this reason, we recommend a 14-day period. That way, you can be sure you’ve also dealt with any bugs that hatched later.
One organic product that we’ve had good results with and also use ourselves is Leaf Insects by Organifer. We started using it because we wanted to stop using chemical pesticides. A major advantage of this product is that you can use it preventively, against mealybugs you’ve found, and as a systemic treatment. One important drawback: it smells strongly of garlic, so we recommend not using it indoors. Take your plants outside and treat them there instead.
Leaf Insects by Organifer works by entering the plant and making its sap taste unpleasant. If you use it preventively, new mealybugs will be less likely to settle on your plants. If you use it as a treatment, the mealybugs on the plant will starve. You can apply this product by spraying it onto the plants with a spray bottle. We recommend spraying the plant thoroughly so the product reaches every part of your cactus or succulent. You can do this once a week for 2–3 weeks. You’ll see the number of mealybugs decrease during this time. Sometimes they remain attached, but they are already dead and will fall off when touched. If you spray the product on your plants, we recommend not misting or spraying them with water during this period. This dilutes the product and makes it less effective.
You can also apply the product when watering. This makes it systemic and allows it to reach pests around the roots too. If you do this, we recommend watering at the same frequency as usual. Watering more often can cause rot. We would only water from above if your pot is sealed. Otherwise, all the water will drain through and the treatment will be less effective. If your pot is not sealed, you can place it in a saucer.
Interested in Leaf Insects by Organifer? You can find the link to the product here and at the bottom of the blog. Mixing instructions are available on the product page.
A third effective method of control is introducing natural predators. The advantage is that this is organic and certainly effective, because natural predators know where to look and can find well-hidden mealybugs too. There are drawbacks as well: you have to be comfortable suddenly having lots of extra little creatures in your home. Natural predators also eat a lot, so if you only have a few mealybugs, they will quickly starve, often before any new eggs have hatched.
There are also minimum and maximum temperature limits to consider. Mealybugs are not very affected by these, but different natural predators are. This is often not a problem in your home, but if your plants are in a greenhouse, it’s something to keep in mind during cold or hot spells in winter and summer. It’s best to check the active temperature range for each species.
These days, you can easily order natural predators of mealybugs online and have them delivered to your home. Two examples you can use are listed below.
- Green lacewing, Chrysoperla carnea
- Cryptolaemus montrouzieri predatory beetle larvae
- What else can I do to prevent them?
In addition to checking your plants, you can also help strengthen their resistance. Mealybugs are more likely to choose plants with low resistance. This does not guarantee that they’ll leave healthy plants alone, but it can make your plants more resilient. A plant’s resistance is often linked to having the right amount of sunlight and warmth. During the growing season, you can feed your plant once a month, and if it has been in the same soil for many years, you can repot it and give it fresh soil. Both can help increase your plant’s resistance.
Another thing to watch out for is drafts. Is your plant in a drafty spot in your home? Then there is a greater chance that mealybugs could be carried onto your plants by the airflow.
We hope you’re now ready to protect your plants from mealybugs. Did you enjoy reading the blog? Or is there any information you feel is missing? Let us know!
