Have you recently noticed that your gorgeous hydrangeas are looking a little less beautiful lately? Perhaps they are starting to droop, appear generally less healthy, and look a bit discolored. It is possible your hydrangeas are infested by a common pest called a scale insect.
You can figure out whether this is the case by looking for a few signs that are easy to spot. This article will provide you with these clues as well as solutions for preventing this pest from wreaking havoc on your hydrangeas or any other plants you have in your garden and yard.
But just what are scale insects?
What Are Scale Insects?
The scale is a type of insect that attacks the foliage and stems of many kinds of plants. There are actually over 1,000 different species of scale insects in North America alone.
Scales have a tube-like feature on their heads that allow them to feed on the sap of plants. The scale insects will attach to the plant they made home and remain there. In fact, they lose their legs once they have settled on a good spot.
Unfortunately, these pests leave behind a chemical that can result in the growth of a certain mold that can damage the plant. This is precisely why it is so important to know how to tell when you have a scale issue and just what to do to take care of this issue immediately.
If you let a scale infestation get out of hand, it can result in the death of your hydrangeas, which are no doubt one of the jewels of your garden or yard. Keep reading to learn more about how to control a scale insect problem and save your precious hydrangeas.
Signs Your Hydrangeas Are Infested by Scales
To figure out whether your hydrangeas are infested by scales, there are a few signs to keep an eye out for.
If your hydrangeas are wilted and slightly yellow in the leaves, it could be due to scale insects, but you can look closely at your plants for other symptoms as well. You can also search for the pests themselves on your hydrangeas or seek out the residue some of the insects leave behind.
First, let’s take a look at the clues your hydrangeas can give that you have a scale problem. Keep in mind that a few scales on your plants will not harm them; rather, it is when you have an infestation that you should be concerned and take action against these pests.
Signs Shown by Hydrangeas
Your hydrangeas will generally look very weak if they are badly infested by scale insects. The foliage can fall off prematurely and start to appear discolored. Also, you will notice the stems, leaves, and branches wilting.
Two other telltale signs include the appearance of a black fungus on the leaves of the hydrangeas, as well as the residue left behind by the insects. This substance, called honeydew, is a clear, sticky liquid that is secreted by insects that feed on sap. Other insects and animals will sometimes feed on this residue.
Searching for the Scales
Another way to figure out if your hydrangeas are infested by scale insects is by searching for the pests themselves. They can be found as eggs, nymphs (juveniles), or adults.
The eggs look oval-shaped, small, and fluffy. The nymphs appear yellow and very tiny. They can be seen moving around the plant. These are juveniles that hatched recently. The adult scales do not move around, they are brown, and are an oval shape.
Scale eggs can take between one and three weeks to hatch after being laid by a female scale. There can be several eggs laid by one female scale in a single year. Interestingly, many female scales do not reproduce with a male counterpart and use parthenogenesis to reproduce asexually instead.
Upon hatching, the baby scales will move around the plant until they find an ideal spot for long-term feeding. Eventually, some will make their own hard shell and lose their legs after finding their spot.
There are hard and soft types of scale insects.
The hard, or armored, variety make their own durable covering over their bodies that remains there, as these adult insects do not move. These shields are not actually attached to the insects. Rather, they simply sit over the pests.
The soft types of scales produce a great deal of honeydew unlike the hard variety, which secrete none whatsoever. Both types of scale can be flat or spherical in shape.
Solutions for Ridding of Scale Insects
There are a few options you have at your disposal when dealing with a scale infestation. You can use the method of biological control, you can use pesticides, you can apply horticultural oil, or you can use natural products.
The most time-consuming method, but also the most environmentally-friendly, is using natural predators of the scale insect to your advantage. You can attract insects such as parasitic wasps and lacewings to your yard.
To do this, you simply must grow many different varieties of flowering plants in your yard and/or garden. If the predator insects have plenty of pollen around from other plants to feed on, they will remain in the area and kill the scales that are damaging your hydrangeas.
Also, with a steady supply of pollen and honeydew, which they also feed on, parasitic wasps and lacewings will lay more eggs and live longer, in turn, killing more of those pesky scales.
On the opposite side of the coin, there are insects that actually benefit scales. One of these insects is ants. Since they feed on the honeydew secreted by scale insects, it leaves less food for the natural predators. This can result in fewer of these predators in the area.
Therefore, reducing the number of ants in your yard can eventually lead to a decrease in the number of scales on your hydrangeas.
Dust can also deter natural predators from sticking around and killing scales, so make sure you keep your plants’ leaves free of dirt.
Remember that if you do go this route and decide to use only biological control to rid of the scale insects, it can take several months to notice results. However, this can have a lasting effect.
Pesticides and Horticultural Oil
If you choose to use pesticides, you can scrape off as many of the scales you can first. After this, you should spray the plants with pesticide every few days. Keep in mind that scraping off the scales will not do much good if you have a bad infestation.
You should never add pesticides to plants when they are in the flowering stage. It is ideal for you to spray the plants when the scale insects are nymphs as they have yet to create their protective shells.
You can also use horticultural oil. Once again, you can scrape off the scale insects before applying the oil if there aren’t too many. You can use a tool with bristles to help.
Another step that you can do before applying the oil is cut off the leaves and branches of the hydrangeas that have been very badly damaged by the scales. You can make the cut at about a quarter-inch from the base of the branches and leaves.
Now, you can spray your plants with the oil. What this will essentially do is suffocate the pests.
One thing to keep in mind is that your plants should be totally dry when you spray them with the oil. Also, do it on a day that isn’t too humid, and make sure to protect yourself with safety glasses and with gloves if you have sensitive skin.
Many types of horticultural oil will require you to mix it with some water. Thus, keep the bottle shaken up so the oil and water do not separate from each other. Spray the solution on the stems, branches, and leaves of your affected hydrangeas.
It is best to use the oil in the early spring to target the scales that survived the winter. If you still notice the insects when summer rolls around, you can spray the plants with oil again.
If you happen to have an infestation of scales that is on the lighter side, you can put alcohol on each scale insect to kill them. An alternative to alcohol is a neem-based leaf shine.
Another option is an organic pesticide. An example of this is insecticidal soap. If you do use a solution such as this one, you must do so while the scale insects are still larvae. You also must repeat the process several times throughout the hatching season to effectively get rid of the scales on your hydrangeas.
There is also natural pesticide you can pick up that is made from plants that have natural insecticidal qualities. These products are much better for the environment and far less harmful for the affected plants than manmade chemicals.
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.