Bugs!!! The good and the bad!
While having the correct light levels and watering properly are two of the most important steps in growing healthy indoor plants, houseplant growers also have to constantly monitor their plants for signs of pests. There are many types of houseplant bugs, and arming yourself with a little information goes a long way toward preventing or eliminating an infestation.
Preventing houseplant pest infestations
Certain houseplants are definitely more prone to pest issues than others, but houseplant bug problems are often prevented by following a few simple steps.
Carefully inspect all new plants before bringing them into your home. Many types of houseplant bugs piggyback their way into your house from the nursery where the plants were grown. Before buying new plants (or taking in “strays” from friends and family), be sure to examine the plant from top to bottom, looking on leaf undersides, along the stems, and even in the soil for signs of the common houseplant insect pests I’m going to introduce you to below.
Even if you think a new plant is pest-free, it may have pest eggs or young pests that you can’t yet see. Before putting any new houseplants with ones you already have, put it in solitary confinement in a separate room for a few weeks. Watch it carefully for signs of houseplant insect pests and only put it in close contact with other plants after it’s been confirmed to be pest-free. You can also place a few yellow sticky cards just above the top of the plant. Many pest insects are attracted to the color yellow, and they’ll quickly get trapped on the card. Check the card every few days for any insects. If you have some on the card, you probably have many more on the plant itself.
Before moving them back indoors, do a “detox” on any houseplants that have spent the summer outside. While most houseplants love to be outside during the warmer months, they often come back inside with several different types of houseplant bugs hitch-hiking on them. The day before moving houseplants back indoors, spray the entire plant – including the lower leaf surfaces and stems – with a sharp stream of water from the hose, using a spray nozzle that emits a forceful spray. This is often all that’s needed to dislodge any pests before moving the plant inside.
Keen observational skills definitely allow you to control many types of houseplant bugs before their populations explode. Examine plants weekly throughout the year, checking for both the insects themselves and signs of their damage.
Another sign that indicates you may have one of several different types of houseplant bugs is the presence of a sticky substance on the plant itself, or on the surface of the table or floor beneath the plant. This shiny, sticky substance is called honeydew, and it’s the excrement of several different pests, including almost all of the houseplant pests mentioned below. The presence of honeydew is a clear sign of pest issues.
The warm, consistent temperature of most homes is ideal for rapid pest breeding. Plus, without ladybugs, parasitic wasps, and other beneficial insects in your home to keep pests in check, houseplant insect pests can go from numbering just a few to an all-out infestation in no time flat. Here are five of the most common types of houseplant bugs and what to do about them.
Adult fungus gnats are super annoying. These minuscule black flies are the classic example of a nuisance pest. When an infested plant is disturbed, a cloud of tiny flies lifts off the soil. Mature gnats life for about a week, and although they’re a pain, they don’t damage your plants. Neither do the larvae, who largely feed on the fungi that naturally grows in potting soil. Because the eggs and larvae need water to survive, fungus gnat infestations are frequently the result of overwatering. A simple reduction in watering is often all that’s needed to control this common houseplant pest. But, if that doesn’t do the trick, a product like DE will definitely take care of the problem.
Another of the more common types of houseplant bugs, scale is sometimes difficult to spot. There are many different species, each with a unique appearance, but the most common houseplant pest scales look like little bumps and are found along the stems and on leaf undersides. Scale insects often have a hard, shell-like covering that makes them difficult to spot and control. They can be gray, black, brown, or even fuzzy. Most scales leave behind the honeydew I mentioned above, so if you see a shiny glaze on the plant, check it for scale. When it comes to houseplant bug problems, scale is probably the most difficult to control. I like to wipe them off my plants with a special cotton pad soaked in isopropyl rubbing alcohol. Physically wiping the pest off the plant multiple times over the course of a few weeks offers the best control. But, another option is to use an organic, neem-based pesticide. Take the plant into a garage or outdoors to apply it, and be sure to follow label instructions.
Aphids (Aphidoidea superfamily, Aphididae family):
Aphids may very well be the most commonly known unwanted houseplant pests. However, I've only ever seen aphids on the food crops that I grow in my home and never on my tropical houseplants. It may very well be a matter of preference of them, but I think what they're really looking for is that gooey sap that they get from the plant by piercing it with their mouthparts. They also exude a sticky, sweet honeydew from their rear, which often attracts other pests, like ants—or provides a medium for sooty mold to grow on, which essentially spells disaster for a plant, particularly if it's fruiting.
Aphids are a soft-bodied insect, so they're very easy to squish between your fingers, which I typically do. Like scales, aphids are also viviparous, which means they give birth to live young. Aphids are born wingless, but if you see an aphid with wings, it's a signal that the colony got too crowded and they are looking for a new houseplant for which to feed.
The best way to get rid of aphids naturally is as follows: on a warm day, early in the morning take your infected houseplant outside and spray it vigorously with a hose. Be careful not to break the plant if it's delicate or newly growing. This can be done by spraying short, strong bursts. This should knock down the aphid population naturally. Once you're finished, inspect the plant and crush any remaining ones with your fingers. Repeatedly do the hose-spray method for another few days until you see everything is under control. If you find aphids keep on coming back despite your best hosing efforts, I would then encourage bringing in some beneficial insects, particularly green lacewing larvae or ladybird larvae.
There are many types of houseplant bugs, but spider mites may just be the ones with the biggest “heebie jeebie” factor. Actually, these guys aren’t bugs at all. Instead, they’re close relatives of spiders. These teeny-tiny houseplant pests cause major issues, not just for plants but also for the homeowner facing the infestation. Though you can barely see them without the help of a magnifying glass, once you know they’re in your house, it’s hard to get them off your mind. Spider mites spin a fine, silky webbing, and collectively, they can cover the entire plant with it. If you look carefully, you’ll see tiny specks crawling around on the webbing; those are the mites themselves. But, before you toss your spider mite-infested ivy or palm plant into the garbage, there are a few steps you can take to get this common houseplant pest in check. First, take the plant outdoors or into the shower and “wash” it off with a spray of water. Spider mites are tiny and are easily washed off the plant. Be sure to rinse both upper and lower leaf surfaces. Then, after the plant has fully dried, use a light-weight horticultural oil to smother them. Reapply the horticultural oil every 10-14 days for two more applications for the best control.
Thrips (Order: Thysanoptera):
Thrips are technically a less common insect pest, but I've found that they are most prevalent in my household. I believe they first came into my home through either my herbs or one of my friend's plants, and they quickly spread, as thrips are typically generalists, puncturing the outer layer of a plant and creating a silvery discoloration on the plant leaf. You'll also notice tiny little bits of black frass, which is a nice way of saying "insect poop". One of my most prized possessions, an African blue basil (Ocimum kilimandscharicum × basilicum), which is particularly hardy and difficult to find, had been almost fully ravaged by thrips. I had saved a couple cuttings, which have now almost entirely bounced back thanks to the help of some natural predators, including Thrips Predators (Neoseiulus cucumeris) and Minute Pirate Bugs (Orius insidiosus), which I released in tandem with much success. Additionally, adult thrips are attracted to the color blue, so you can also affix blue sticky traps around your plants to curtail the population.
There are good bugs too!
Isopods are basically a fancy name for rollie polys, pill bugs, or woodlice. They are small invertebrates, with most species measuring from 1/8″-1″ or so.
There are thousands of species worldwide, with several dozen being cultivated in captivity. Technically, isopods are a terrestrial type of crustacean – they’re more closely related to shrimp than insects!
Isopods live in a wide variety of habitats (some even swim, or live in salt water), but the ones we’re interested in primarily live on and in the soil in tropical or subtropical habitats.
Once introduced into the substrate and given time to establish, they play several important roles to help keep the habitat fresh and clean:
Aerate the soil – as they move around, isopods will dig small tunnels and create voids in the soil, allowing air to descend further down into the substrate layer. These voids facilitate plant growth and help keep your substrate from getting waterlogged.
Consume waste – isopods will eat fecal material, decaying plant matter, wood, and deceased feeder insects that your pet may have missed. They’ll help quickly break down harmful waste into less harmful products that plants can use.
Make nutrients more available to plants and fungi – not only do isopods break down waste into more usable types of nutrients, but they also disperse those nutrients throughout the substrate as they dig and move about the vivarium. Plants and fungi can then break them down further, keeping your habitat healthier.
Fertilize plants – What goes in, must come out. Fortunately, what comes out of isopods is great to spur healthy plant growth.
Eat mites and pest eggs – isopods will predate on the occasional pest eggs. They won’t touch reptile or amphibian eggs, but small eggs (such as from mites) are fair game. They’ll help keep pest numbers down in your bioactive enclosure.
Act as a supplemental food source – Many animals, especially dart frogs and small lizards, will predate on isopods. With all the benefits that isopods bring to the bioactive terrarium, this may seem like a bad thing, but an occasional snacking generally has little impact on the isopod population as a whole.
Springtails are associated with damp conditions and organic debris and are found outdoors in soil, leaf litter, decaying plant matter, and rotting wood. They are found in diverse habitats from tundras to cornfields, and they feed on fungi, pollen, algae, or decaying organic matter. Springtails may also inhabit the soil of houseplants or other moist places inside the house. Springtails that infest houseplants are only found in soil that is exceedingly damp or in soil mixes containing high percentages of peat. They feed on decaying roots and fungi and do not harm living plants, but if you have a problem with springtails in houseplants, let the soil dry out and water less frequently. Moisture control is the most effective strategy to decrease springtail populations.
Typically, seeing springtails is a positive thing. Springtails are harmless to people; they do not bite or sting us, nor damage food products, clothes, or furniture. In fact, they are beneficial insects to have in agricultural soils or in one’s garden soil. They play important roles in the decomposition of organic materials, cycling of nutrients, and formation of soil micro-structure. Like most of our under-recognized soil invertebrates, they play a role in the soil food web and contribute to the health of the of soil community. There is also evidence that springtails benefit plant health by feeding upon fungi which may cause plant diseases.
Though there are a handful of other indoor plant pests that may occasionally prove problematic, these five types of houseplant bugs are by far the most common. But, by following the five preventative steps featured at the beginning of this article and using the suggested mechanical and organic product controls, you’ll be able to keep most of these little buggers from causing any real issues.
Remember, arming yourself with a little information goes a long way toward growing healthy, pest-free houseplants. Be smart about your choice of plants. For apartment dwellers, our list of the best houseplants for small spaces offers plenty of great plant choices. Healthy houseplants are better able to fend off pests, too.
Check out Diatomaceous Earth aka DE here