By: Mary H. Dyer, Credentialed Garden Writer
Rubbertree (Ficus elastica) isan impressive plant with huge, shiny leaves, but this cold-sensitive plant survivesoutdoors only in very warm climates. For this reason, it is usually grownindoors. Although healthy rubber tree plants tend to be pest resistant, theycan be infested by several sap-sucking pests. What to do if you notice rubberplant insects? Read on for helpful tips.
Pests on a Rubber Plant
Here are the most common rubber plant insects you may comeacross:
Aphidsare tiny, pear-shaped pests that gather en masse on the undersides of leaves orthe joints of leaves and stems. The pests are usually green, but differentspecies may be red, brown, black, or yellow. Aphids damage rubber tree bysucking the sweet nectar from the leaves.
Scaleare tiny rubber plant pests that attach themselves to all parts of the plant and,like aphids, they feed on sweet plant juices. Scale pests may be either armoredscales, with a plate-like outer covering, or soft, with a waxy or cottonysurface.
Spidermites are difficult to see with the naked eye, but they are seriousrubber plant bugs that puncture leaves to draw out the nectar. You know mitesare on the plant because of their telltale webs. They often appear whenconditions are dry and dusty.
Thripsare tiny rubber plant insects with wings. The insects, which may be black orstraw-colored, tend to jump or fly when disturbed. Thrips are more troublesomefor outdoor rubber tree plants, but they can also infest plants grown indoors.
What to Do About Pests on a Rubber Plant
Insecticidal soap sprays are usually effective againstrubber plant bugs, but you may need to re-spray every couple of weeks until thepests are under control. Use a commercial product, as homemade sprays are oftentoo harsh for indoor plants. Neemoil is also an option.
Horticultural oils kill pests by suffocation and areespecially effective against difficult rubber plant pests like scale andthrips. Read the label carefully, as some indoor plants are sensitive to theoils. Cover furniture before applying.
Chemical insecticides should be used only as a last resort.If you use chemicals, be sure they are registered for indoor use.
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Read more about Rubber Trees
Common houseplant pests
The list of seven insects and mites are by no means an exhaustive list of houseplant pests, but they are the most typical ones that you'll likely see in the home.
Scale are primarily immobile insects that stick themselves to stems and leaves. They come in two families: Coccidae and Diaspididae. The brown soft scale (Coccus hesperidum L.) shown here is a common houseplant and greenhouse pest.
Common brown scale (Coccidae and Diaspididae families)
The first time I noticed a scale insect was on a jasmine plant that I had purchased at the farmers market. I didn't see the insect at first, but I did notice that some of the bottom leaves of the plant were shiny and sticky. Upon closer inspection, I noticed brown nubs stuck to the woody stem and underside of leaves, closest to the central vein. This was scale.
There are different varieties of scale but by far the most common is the brown soft scale (Coccus hesperidum L.). They are rather inconspicuous—and don't look like a typical insect—unless you know what to look out for. Firstly, they're ovate, only about 3-4 mm long and about half as wide. They can range in color, but are most often brownish in appearance (hence the name), but I've also seen them in shades of yellow, amber, and even olivaceous. They're called "scales" largely due to their scale-like appearance on a plant, due to waxy or armored coverings. They are often seen in clumps along a stem, sucking away at the plant's juices with their spiky mouthpart.
They are only mobile when they are born. Soft scales, which are just one of the groups of scale insects, can reproduce both sexually or parthenogenetically, which means that they can produce young without fertilization. Quite unique in the insect world, the female scales are ovoviviparous, which means they give to birth to living young by hatching the eggs while they are still in their mother. This is the same in Madagascar hissing cockroaches, which are not a plant pest, but an insect that I raise, and I'll be the first to say that it can be shocking that one day you'll have 2 cockroaches and the next day 20X that amount. Same goes for the scale insects. I say this only because you can't really get rid of the eggs unless you get rid of the adults. Once the young, which are called "crawlers" are born, they'll disperse along the plant, find a place they like (usually around some new growth), and literally plant themselves there for the remainder of the time—reaching maturity at around 65 days.
Scale can be a real problem indoors because quite frankly, they have a good temperature year round, which means they'll likely reproduce around the clock. Good news, however, is that scale are, as I shared, relatively immobile, so if they are contained to one plant, then you can control them. Most people choose to discard the plant. Though it was slightly stunted in growth, I decided to keep my jasmine to see if I could revive it. First, homemade soap sprays aren't that effective on scale, partially because the scale on the outside of the insect acts like a shield. You'd want to get it under the cap of the insect.
What I did was as follows:
1. Place a plastic bag or some covering around the soil of your plant. This prevents any scale from falling into your soil.
2. Get a natural, rosemary-based insecticidal soap. Spray this on the plant so it's nice and soapy.
3. Run your fingers along the stems and plant leaves, turning up the scale with your fingernails. If you don't want to touch the insects, you can use an old toothbrush or even a toothpick, but I feel as if I have more control and accuracy with my fingernails. You may notice some scale fall onto the plastic bags pick them up and discard them. Really be sure to look over the entire plant. My jasmine had a woody stem and the scale looked like part of the stem, so don't be fooled! If helpful, get a pocket magnifier to look over the plant, including the creases of where the leaf meets the stem.
4. After you've sufficiently soaped and scraped the plant, give it a good, sharp spray with your hose or your shower. You'll want to get all the soap off the plant so it doesn't affect growth. Keeping a plant strong, healthy and growing, can often keep insects at bay.
5. Check the plant again for the next three days, making sure that you hadn't missed any scales. If you did, you can repeat steps 1-4. Check again once a week for the two months, just to make certain you got all the little buggers.
Mealybugs are a type of cottony, mobile scale that often can be seen in clumps on your houseplants. They are generalists, and I've particularly found them on everything from my potato plants, succulents, Stromanthe and Plerandra.
Mealybugs (Pseudococcidae families)
I'm not quite sure how mealybugs first got into my home, but I first noticed them on my potato plants that I was growing in my closet garden. Potatoes, particularly the leaves and stems, grow incredibly fast, so I was monitoring them pretty closely. I first planted the potatoes from ones that I purchased in the farmers market and that started growing "eyes". Interesting enough, I had more potatoes that began growing eyes in my fruit basket, and mealybugs would just "show up" on them. Still to this day I'm befuddled by their spontaneous generation.
Mealybugs are an unarmored scale insect, and I personally think they are more difficult to control than the common brown scale. This is for a few reasons. First is the most obvious: mealybugs move. Though its slow movement, if any plant is touching another, there is a chance the mealybug will hitch a ride on a new leaf and spread. Secondly, though their soft, cottony white appearance is quite obvious on a plant, they have a tendency to hide out in the damnedest of places, like the crotch of a plant or in a leaf that has yet to unfurl. Additionally, they have waxy secretions, giving them their cotton-like appearance, which can serve as some basic protection. And lastly, they breed like rabbits of the insect world. Females can deposit around 600 eggs in loose cottony masses, often on the underside of leaves or along stems. The early instars will hatch in about a week and this often causes a population explosion.
As such, it's important to get mealybug populations in control. Some will toss out a plant completely, but I did no such thing. Instead I did a three-pronged effort, involving the release of two beneficial insects—the green lacewing (Chrysoperla carnea) and highly effective, aptly named mealybug destroyer (Cryptolaemus montrouzieri), and also spot treatment using a q-tip and isopropyl alcohol. Dabbing the alcohol directly onto the mealybugs will easily kill them on the spot, but the upside to releasing the beneficial insects is that the insects can often get to places in a plant that you often cannot get, so I believe both methods—at least for me—have worked the best.
Aphids are another plant-sucking insect that often congregate in large numbers. I most often see them on my herbs and I take enjoyment in squishing them between my fingers, since they are full of plant juice. No wonder why some ants like to harvest the sweet goodness coming out of these globulous insects.
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.
Whiteflies (Trialeurodes vaporariorum) closely resemble tiny white moths, but they are closely related to aphids and scales. Like aphids, they produce honeydew from sucking plant juices, which can then attract sooty mold, which can further harm plants.
Common whitefly (Trialeurodes vaporariorum)
At first whiteflies, which are more closely related to aphids and scale, can be mistaken for little white moths or even mealybugs. Unlike their fellow pesky counterparts, they will easily take flight if you disturb them. I first noticed whiteflies in my home when I started growing potatoes indoors (I mean seriously, potatoes indoors brought every pest imaginable!). Whiteflies are more or less generalists when it comes to plants. I noticed that they first were congregated in small numbers on potatoes, but they soon started to alight on my elephant ear plants, which were nearby.
Adults will lay eggs while they are eating (efficient little beasts, aren't they?). Eggs will hatch in less than a week and then their nymphs, similarly to scale, will crawl a short distance, plant themselves, and suck the plant until they go into a resting stage at about the 3 week point. In about four, maybe five weeks, they begin to emerge as adults and the process repeats. As indicated, both the nymphs and adults of the whitefly use their mouthparts to suck juices from plants, which can cause leaves to yellow and fall off prematurely. Additionally, whiteflies, like aphids, exude honeydew, which becomes an attractant for sooty mold. If you allow whiteflies to multiply, then they can attack your plant enough to weaken it.
Whiteflies are attracted to the color yellow, so the best way to catch them is by having yellow sticky traps, blasting the leaves with short bursts of water from a hose, and also introducing a beneficial insect, like a green lacewing, ladybird beetle, or whitefly parasite (Encarsia formosa). All three techniques are highly recommended, in that order.
Red spider mites (Tetranychus sp.)
Mites are technically not insects but they, like insects, are Arthropods. They are probably some of the most feared of the common household insect pests, largely because they are so difficult to get rid of.
Spider mites are nearly naked to the eye. You often need a magnifying lens to spot them, or you may just notice a reddish film across the bottom of the leaves, some webbing, or even some leaf damage, which usually results in reddish-brown spots on the leaf.
Earlier in the year I was gifted an Alocasia micholitaiana 'Frydek', which is a gorgeous velvety green alocasia. I typically always check my houseplants before bringing them indoors, which is a proactive way to make sure no pesky insects are in tow, but you can't always rely on eyesight. Within about three weeks, I noticed some webbing and the start of brown dots on some of the mature leaves. Before mites could spread to the other plants, I took the Alocasia and washed it thoroughly in the shower and made sure the humidifier was on daily. Mites prefer dry conditions, so keeping the air humid and the plant on the wet side (something an Alocasia prefers anyway), was able to save the plant, although it still bears the battle wounds of the mites.
Spider mites also have a range of natural predators, including other mites like Phytoseiulus sp. and generalist predators like minute pirate bugs and lacewing larvae.
Fungus gnats (Bradysia sp.)
I'm including fungus gnats as a common houseplant pest, only because they are common and more of an annoyance to people versus plants. Fungus gnats look similar to fruit flies, and are often mistaken as such. They are pretty feeble fliers and can often be seen circling around soil, particularly if it's fresh, damp compost. Their larvae, which are really the more cause for concern here, prefer to feed on fungi in the soil, which you can only get in moist conditions. They technically can eat plant material, but if the fungi levels are high, they often won't.
I ended up getting quite a few fungus gnats when I started to grow microgreens in a nice bed of compost. The adult gnats will often hang around the soil because that's where they like to lay eggs, but adults are harmless. I basically got some BTI, or Bacillus thuringiensis, which is a natural and safe bacteria that you can sprinkle in the soil and some yellow sticky traps to catch the adults. The problem was solved within three days. Additionally, you can bring in a natural fungus gnat predator, such as Stratiolaelaps scimitus, which is a type of mite.
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.
When you first bring home a houseplant, you may want to take a few precautions to make sure that it has no pests that will spread to your other plants. Pictured here, an Alocasia reginula.
Common garden pests and how to kill them
Many garden insects do no harm at all and some – the beneficial insects – are garden superheroes. But if you find yourself on the receiving end of plant-assassinating bugs, you'll likely employ any method to get rid of them.
If left unchecked, scale, stink bugs and even millipedes can do some damage in the garden.
Centipedes vs millipedes? Not sure which is which? Next time you see a bug that has lots of legs, take a closer look. Millipedes have two pairs of legs from each body segment, while centipedes have only one pair per segment. The body of centipedes is also fairly flat, while the millipede's is more rounded.
Millipedes feed mostly on decaying plant material, although they sometimes take a fancy to young seedlings. When they do, they'll eat the leaves, stems and roots. Centipedes are carnivorous and feed on insects and spiders.
An overabundance of millipedes can be a nuisance, but they are easy to control, without chemical warfare. They like moist environments, so remove any rotting leaves, wood and other kinds of moist, decaying plant matter, or anything where moisture can collect. They will not survive long in dry conditions without any food.
Scale may be your nemesis, but there are all sorts of scale insects.
Have you those strange white blobs on the undersides of your hydrangea leaves? These are the waxy egg masses of cottony hydrangea scale (Pulvinaria hydrangeae). First recorded in New Zealand in 1977, the young nymphs hatch from midsummer and suck sap from the undersides of leaves. They move to the stems in late summer where they overwinter before maturing in late spring. Severe infestations will weaken plants.
Now is as good a time as any to peer beneath your bushes for signs of them. If you see them, remove the leaves and bin them.
If you'd rather spray, the best time to do so is when the nymphs hatch (there is only one generation a year) from midsummer. You will need to spray several times to ensure you target the nymphs as they hatch. A pyrethrum-based spray works when newly hatched if spraying in autumn, use a mineral oil spray.
There is another scale that looks similar to the cottony hydrangea scale and that's the soft wax scale (Ceroplastes destructor) – a serious pest on citrus and sometimes kiwifruit.
As above, there is only one generation a year, and they suck the sap from plants and can severely weaken them if numbers are high. Use an oil spray to control them.
Research from a trial at Kerikeri found that the best time to control them is around mid-January to mid-February, when the new generation is produced, though you can still spray them now. Make sure you spray on the undersides of the leaves as well as the stems for good coverage. It may take a couple of seasons to control them completely.
Flax bushes are not immune to scale either. Large infestations of flax scale, which looks a bit like mealy bug – white and woolly – can be very damaging to plants. They suck the sap of leaves and weaken them, making them susceptible to disease. Stressed plants seem to attract more scale.
The young scale insects are very active and can be blown from plant to plant by the wind, so they can get around quite quickly.
They are protected by their cottony surrounding, their shell and the fact that they tend to hide where the leaves sheath together at the bottom of the fan and on the rhizome – places that are hard to spray.
If you use oil sprays, make sure you spray several times – every two to three weeks – until you get on top of the problem. Let the oil run down the leaf sheaths and bases to get to the scale that you cannot see. You could also try a systemic spray as the scale sucks the sap they will ingest the insecticide.
The green vegetable bug, aka stink bug, is common in gardens throughout New Zealand. They suck the sap from summer vegetables and ornamental garden plants, which can result in deformed shoots and fruit and flower drop. The young, wingless nymphs range in colour from green, brown or black, with orange, red or white markings. You can use a pyrethrum-based spray to control them spray in the morning or evening when they are least active.
Invaded by passionvine hoppers? The lacewing adults are tricky to control as they flit off when they see you coming. Give them a blast with a pyrethrum-based spray.
If numbers are high you'll need to spray continuously throughout the season, and probably the next two, until you get on top of them.
Whatever bug you may have, if you get on top of it when first sighted, you'll go a long way to controlling the numbers before they build up.
These small, slender insects are brown, black or yellow and have fringed wings. Thrips damage fruit trees and ornamental plants. They suck on plants, which results in silvering and mottling of the surface of the leaves. They also leave behind black, shiny flecks of excrement. Read more about controlling thrips.
Known for quickly devouring the foliage of vegetable crops such as tomatoes, peppers, potatoes and eggplant, tomato hornworms measure up to 4 inches long and feature posterior horns. The adults are large moths that appear at dusk. Hornworms in the garden leave large amount of black excrement on the ground near plants. Read more about controlling tomato hornworms.
When any of these pests hit your garden, you need treatment you can trust. Fortunately, GardenTech® Sevin® brand insecticides quickly and efficiently controls all of these pests — and many more. Sevin® Insect Killer, available in liquid Ready To Use, Ready To Spray and Concentrate forms, kills more than 500 types of insect pests by contact. Then it keeps on protecting fruit and vegetable gardens, ornamental and flower gardens, lawns and around your home for up to three months. You can even treat many favorite garden edibles, including tomatoes and peppers, right up to one full day before harvest.*
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GardenTech is a registered trademark of Gulfstream Home & Garden, Inc.
Sevin is a registered trademark of Tessenderlo Kerley, Inc.