Mealybugs and How to Deal With Them
Mealybugs are a common plant pest that sometimes go unnoticed until they cover a plant, maybe even multiple plants. They produce honeydew, which can lead to sooty mold if allowed to stay on the plant. They also feed on the sap within your plants and inject plant toxins. Luckily, they are a fairly easy pest to treat, if caught early. The rate at which they reproduce can cause a problem when it comes to management. Here we will go over what to look for and what to do about them when you come across the annoying little plant pests!
What to look for
Small, white, fuzzy areas on your plant may not be mold- though it can look very similar! Mealybugs can have a variety of appearances, though all of the ways they present are akin. There are over 2,000 species of mealybugs, each with their own unique appearance, though all mealybugs are oval shaped, wax covered, and white to very light grey. Their bodies are segmented, though the segments aren't always easily noted. Some species can grow waxy filaments either down the side of the body to resemble legs, or as thin, waxy tails. Adult females are typically about one centimeter long. The above description covers females and nymphs, though young nymphs do not yet develop the waxy covering and may appear to be pink, yellow, grey, or orange. Adult males look very similar to small gnats with four eyes and two wings.
The wax can appear to have a fuzzy texture. This is especially true for the ovisacs laid by the adult females. Ovisacs hold the eggs and can appear to be white mold with the naked eye.
It is important to understand the life cycle of any insect to properly treat the infested plant or plants to be sure they take the least amount of damage possible. Some species of mealybugs will produce several ovisacs, while others can only produce one in their lifetime. After the ovisac containing up to 400 eggs is formed, it can take anywhere from 3-14 days for the eggs to hatch. Depending on the species and the environment, it could potentially take even longer. Typically, females will lay ovisacs in protected areas of the plant, such as tight angles between leaves and stems or on the underside of leaves. They favor new over old growth, so plant crowns are another popular place to find both adults and eggs. Females typically go through four instars before they become adults and can lay eggs, while males will have four molts, become a pupa, then emerge as the winged male. They can complete their life cycle in anywhere from 20-75 days, depending on the environmental factors and the species. Males often lose their mouthparts in the adult stage, but females can feed throughout their life.
Plants should be monitored for all types of pests regularly. Mealybugs, as well as many other pests, prefer the undersides of leaves and new growth. Be sure to look thoroughly in the tight nooks and crannies of your plants, as well. Both adult mealybugs and eggs can be found in the well protected areas of the plants. It's a good idea to give your plants a good look through once a week, especially if they live outside or you bring home new plants. Plants that commonly get mealybugs include succulents and cacti, as well as tropical plants like orchids and philodendrons. This doesn't mean that common outdoor plants are safe! Grapes, hibiscus and many other plants usually grown outdoors also get mealybugs.
Mealybugs are fairly easy to treat! Heavily infested parts of the plant should be removed, placed into plastic bags, and discarded. If you choose to use a pesticide, be sure it will target mealybugs and that you follow the label. When it comes to pesticides, the label is the law. Only apply following the directions provided. The wax of the
older instars repel water and chemicals that may be applied to them, so keep that in mind when treating. Treating plants with systemic pesticides before you see pests can help to prevent any infestation.
If pesticides aren't your thing, combining one part water with one part 70% isopropyl alcohol in a spray bottle or on a q-tip will help to kill the pests without pesticides. Be sure to wipe the alcohol and mealybugs off of your plants if you choose this method. This method works for mealybugs because, while they are a form of scale, they are a soft-bodied scale. Alcohol is not an effective treatment for hard bodied insects, like other forms of scale.
Beneficial insects are also an option! Minute pirate bugs, parasitic wasps, some species of ladybugs, lacewing larvae, and predatory flies all have mealybugs on the menu. If you are ordering ladybugs, please be sure they have been sustainably harvested and they are a native species to your area. There are invasive species of ladybugs that should not be released into the landscape. Of all of the predators, lacewings are my personal favorite due to their voracious appetite and availability to purchase as eggs or larvae.
Be sure to check your plants again, even after you have treated the mealybugs in case there are more you couldn't see or eggs that have hatched.
Overall, mealybugs are annoying and can cause a lot of issues for plants. Luckily, they are easy to treat with persistence, especially if your plant collection is small. If caught early, they can be treated quickly and easily. Make sure to scout your plants and treat them accordingly!
As always, if you are concerned about your plants in any way, do not be afraid to reach out!