If you're a houseplant collector, having a few pests is inevitable. In this post we'll talk about the ones you're likely to see, their favorite hiding places, what times of year you can expect to see them, and how to make them go away (without throwing a plant in the trash can).
Thrips are tiny black little bugs that live on the leaves of plants. We have seen them primarily on philodedron plants, particularly the philodendron selloum and monstera, but we have also seen them on alocasia low rider and borneo giants. While they are slow to kill a plant, they can gradually make a plant's leaves turn yellow while they do their work. Be sure to inspect the underside of leaves. They seem to cut straight lines across a leaf's main vein which cuts off the majority of the leaf's nutrients, leaving a leaf to hang down from the stalk and eventually turn the leaf brown. Spray the leaves (front and back) with an organic insecticidal soap every week for 3-4 weeks until you've beaten them back to a manageable level. As the plant begins to rebuild and grow new leaves, it's a good sign when more leaves are healthy than yellow. Keep an eye on these pests and apply the spray as needed - we have seen these pests year-round. Avoid overwatering your plants as moist environments seem to breed pests.
Mealybugs are an especially disgusting and repulsive pest. They are mush larger than thrips, and can easily be seen when present. You will often see a series of white cottony clumps of fuzz on your plant when they are present, and upon closer inspection, you'll see the bugs themselves further towards the middle of the plant. Look closely between the stalks of plants as they seem to like to hide between tight spaces. We have found these pests on plants with many nooks and crannies, in particular the sago palm, ponytail palm, and foxtail fern. Start by knocking the pests off with a small paint brush, making sure to get in between the cracks of leaves, stalks, and stems. Be sure to kill the pests by cleaning them off the plant with a paper towel and crushing them. Knock all the pests, white fuzz, and egg pods off the plant with the brush, then apply a good coating of organic insecticidal spray to the entire plant and let dry. Keep an eye on the plant for the following weeks. These seem to be fall-winter bugs.
Scale bugs are deceptive as they commonly present as a white fuzz ball on the center of a cactus' thorns. They can appear year-round but as cacti are heat-loving plants, they seem to appear when the plant is overwatered or left in cool damp areas. Start treatment by taking the plant outdoors with a hose or watering can and begin pouring water over the infected area. While applying water, use a small paint brush to poke and dab the infection until the fuzz material loosens and falls off. As much as possible, be sure to remove the material from the plant and soil entirely. Apply a thorough coating of organic insecticidal soap on the entire plant after the water dries, and keep an eye on the plant in the following weeks, repeating the procedure if necessary.
FRUIT FLIES AND FUNGUS GNATS
Small flies are a common and very annoying houseplant pest that often present year-round. They do not seem to harm the plant itself, rather they burrow in the soil and reproduce quickly, making your hanging basket or potted plant a living fruit bowl. Start by making a mild neem oil solution, then water the plant thoroughly with this solution. Let the plant dry out completely between waterings as these bugs seem to thrive in damp soil more so than dry soil. Apply a second watering of mild neem oil if necessary after a week or so. We have seen these pests primarily in plants that are overwatered, independent of the plant type. Strings of pearls, fiddle leaf figs, dracaenas - almost any plant is susceptible to these pests as they are after the soil, not the plant.
Spider mites often present on leafy plants that do not require constant watering, as these plants are left alone for 1-3 weeks giving the pest time to colonize and create webbing. Plants that require more regular maintenance are usually disrupted enough that the pest does not have time to take over. Leafy low maintenance plants such as Chinese Evergreen (aglaonema), Rubber Plant, ZZ Plant, Jade Plant, Bird of Paradise, and Ponytail Palms are all susceptible to these pests are you might not check them for a week or two, giving the pest time to do its work. Be sure to visually check your low maintenance plants every few days for signs of life. If found, clean the plant with a damp towel and paint brush to clean the area. You could spray the area with an organic insecticidal soap for good measure.
MILLIPEDES AND SNAILS
We have seen a few larger bugs on plants, primarily plants that have been shipped to our shop directly from growers in more tropical climates. Millipedes, snails, and even frogs (yes, frogs!) have shown up in our shop in either the soil of plants or around the base of plants. For soil-based creatures like millipedes, start to water the plant every week or twice weekly with a mild neem oil solution as instructed above for fruit flies and gnats. Unlike flies, these soil-loving creatures do harm a plant's roots and stalks (in the case of snails), so it is critical to kill these pests (ok you can simply remove the frogs, no need to kill them!). After a thorough watering with a neem oil solution, any bugs that have not been killed may come to the surface of the soil, so take a few minutes to dig around lightly with a trowel or stick to uncover any pests in the top 1-2 inches of soil. If found, remove them while wearing gloves and be sure they are disposed of properly. Repeat this treatment weekly for every watering for 1-3 weeks to root out the pests and resolve the issue. This issue is more prevalent when you first get a new plant as it may have just arrived from a tropical climate; once the plant has adjusted to its new home indoors, the pests will struggle to survive.