Almost invisible to the naked eye, spider mites are vicious little creatures that feed on plants’ sap, damaging both indoor and outdoor plants. When dealing with spider mites, it is important to know how they “operate” in order to get rid of them once and for all.
As spider mites feed on a plant’s fluids, they secrete a sugar-rich sticky substance called honeydew. Because spider mites tend to reside on the bottom of the host plant’s leaves, spotting an infestation can be difficult. Spider mites also leave behind tight webs that protect their colonies.
Learning as much as possible about spider mites will allow you to spot these tiny little insects before they can hinder your plants’ growth. Fortunately for us, there are several ways to detect spider mite infestations early on.
Why Are My Plant Leaves Sticky?
If your plants’ leaves feel sticky to the touch, then it is highly likely that they are infested with sap-feeding pests. Aphids, mealybugs, whiteflies, scale insects, and spider mites are among the many bugs that secrete honeydew after ingesting phloem sap.
Plant sap is a highly sugary substance that contains very little protein. To be able to get all the protein they need, bugs must consume large amounts of it, which leaves them with a considerable sugar surplus.
Unable to convert it all into energy, they end up expelling it in the form of honeydew, a clear sticky substance that is quite easy to recognize (at least to someone who knows what they are looking at).
Most bugs reside on the upper side of plants’ leaves, which makes it relatively easy for plant owners to spot infestations early on. With spider mites, however, the sticky residue is often found on the bottom of plants’ leaves, as that is where these little creatures prefer to reside.
To be able to tell if your plants are infested, you will have to inspect them closely, touching both sides of each leaf, as well as their stems.
What You Need To Know About Spider Mites
Let me start by pointing out that, at least from a technical viewpoint, spider mites are not classified as insects. As their name suggests, spider mites are related to spiders, which means that they are also a type of arachnid.
Spider mites are particularly common in North America and can target both indoor and outdoor plants—they are especially fond of greenhouses. They thrive in dry and warm climates and are particularly prolific in environments where their enemies have already been eradicated by pesticides.
Spotting Spider Mites
So, what do these pests look like? Adult spider mites are oval-shaped and red, brown, or orange in color. In terms of size, they are incredibly small: less than 0.04 inches or 1 mm. Young spider mites are even smaller, meaning that they are impossible to see without a magnifying glass.
Like many other pests, spider mites live in colonies and feed on plants’ fluids. They do so by piercing the host plant’s leaves, leaving many teeny tiny light-colored dots all over them.
How Spider Mites Reproduce
The main reason why spider mite infestations often go unnoticed is that these creatures reproduce at a remarkably fast rate.
A single female spider mite can lay as many as twenty eggs a day and can live for up to a month, which makes over 500 eggs per female on average. Spider mites’ ability to reproduce so fast allows them to develop a high level of pesticide resistance within a relatively short time. Eggs usually hatch in spring and only take 5 days to grow into adults.
After being exposed to a certain pesticide, spider mites become somehow immune to it, which is why chemical control may not work if the same pesticides are used over a prolonged period of time. To get rid of spider mites once and for all, you may have to try different pesticides.
How Spider Mites Affect Your Plants
Let us start by pointing out that the most common spider mites are two-spotted spider mites, which can be quite difficult to spot without a magnifying glass. Their eggs are oval-shaped and translucent, which makes them practically undetectable to the human eye.
Once an egg hatches, it turns into a larva, a nymph, and finally, an adult. At first, adult two-spotted spider mites are either green or orange in color, but as they mature, they gradually turn red.
If your plants have been attacked by these bugs, you may be able to tell how advanced the infestation is by their color. If you see a large number of red, green, and orange spider mites, that means that your guests have been working hard to expand their colony.
If you see quite a few red bugs but very few green and orange ones, that means that you are primarily dealing with adult spider mites that haven’t had time to lay a large number of eggs.
As previously mentioned, spider mites are sap-feeding bugs, meaning that they feed on plants’ fluids. If we were to look closely at an infested plant’s leaves, we would certainly see many biting marks all over them.
One of the first signs of a spider mite infestation is discoloration. At first, you may think that your plant simply needs more water or fertilizer, but that is not why its leaves are turning increasingly pale. As spider mites feed on a plant’s sap, they suck out much of its chlorophyll, the pigment that gives plants their vibrant green color.
The less chlorophyll a plant has, the paler its leaves are going to look due to its inability to absorb light (chlorophyll plays an essential role in photosynthesis).
More often than not, when spider mites target a plant, its leaves don’t turn entirely yellow. Instead, you will notice many yellow dots right where the spider mites have been feeding—a phenomenon called stippling.
Sometimes, leaves respond by turning brownish or developing a gritty texture. In case of a severe infestation, there is a good chance that your plants’ leaves will appear dusty and opaque.
As spider mites feed, grow, reproduce and die, they will leave a wide range of gross things behind, such as fecal matter, webs, shed skin cells, and, yes, even dead bodies. You may want to think twice before you touch your infested plant with your bare hands!
How to Identify Spider Mites in Your Plants
When spider mites infest a plant, the texture and appearance of its leaves will start changing within a short period of time. There are three key ways in which you can tell that something is wrong with your plant:
- Its leaves look and feel gritty
- Its leaves look dusty but are not actually covered in dust
- Its leaves feel sticky to the touch
If your plants’ leaves are covered in an unusual sticky substance, then it is highly likely that you are dealing with some kind of sap-feeding pest. Aphids, mealybugs, whiteflies, scale insects, and spider mites are among the many pests that secrete honeydew after feeding on phloem sap.
What to Do if You Find a Spider Mite Infestation
The answer depends on advanced the infestation is. If you see a small amount of honeydew and webbing, that means that the infestation is not yet advanced.
In this case, you may want to try a natural remedy or a mild insecticidal spray before you move on to more aggressive methods. Start by soaking a cloth in warm water and wiping each leaf carefully. Don’t forget to wipe the underside of each leaf, as that is where spider mites tend to hide.
If the problem persists, try cleaning the plant with insecticidal soap or apply another natural insecticide. Remember that you may need to apply insecticidal soap multiple times to get results. With a cotton bud or even with your finger (you may want to wear gloves for this, though), gently scrape off any substances that do not belong on your plant: honeydew, webs, cotton-like masses, carcasses, etc.
If none of these remedies works, chemical insecticides will most probably solve the problem. Of course, you could also discard the affected plants, but that’s not always an option.
When dealing with spider mites, contact products are usually very effective. These products need to be applied in a way that covers the mites’ bodies.
Honeydew on plants does not always indicate the presence of bugs. If you see honeydew on your plants but no bugs, you should consider other possibilities. Check out my blog post to learn more: Honeydew on Plants but No Bugs? Here’s Why
Final Thoughts
Like aphids, mealybugs, and many other sap-feeding insects, spider mites can leave a sticky substance on the plants they infest. Spider mites are mainly interested in the protein content of sap. Unfortunately for them, sap contains far more sugar than protein.
This forces them to consume large amounts of sap, leaving them with a significant sugar surplus which they excrete in the form of a sticky substance called honeydew.
If you get a magnifying glass, you will be able to see webs, carcasses, shed skin cells, and fecal matter—all clear signs of a pest infestation.
