Pest attacks are much more common outdoors in the garden, but even the most seasoned house plant owner will eventually fall victim to an attack indoors. The trick is to be observant of your plant and then when problems arise act decisively. If you follow this rule your plants have a much better chance of making it out the battlefield with minimal or no lasting damage.
Organic v.s Chemical Control
Where possible we promote the most eco friendly method for pest eradication and control. But the truth is that having plants indoors severely limits or completely removes the option to use truly organic pest control, for example outside Aphids will eventually be eaten by ladybirds. So while we detail our favorite method, we also list a chemical option where appropriate.
The Common Pests
The most common ones are listed below, along with their identifying symptoms and suggested treatments. If you're having problems with something different let us know and we will try and help you out. Sometimes your plant will have a disease rather than a pest problem in which case you will need to head on over to our disease page.
Aphids suck sap usually from the new soft plant growth, the tips, flowers etc, however they can attack any part of the plant. Normally hidden from obvious sight, i.e. under the leaves, they are typically green, but can also be black or grey and arrive in small but quickly reproducing colonies. They can be seen easily with the human eye if you look closely.
They tend to mass together in large numbers making them easy to spot and identify. Look for sticky honeydew deposits on the plant and their white or grey "husks" littering the soil and sticking to the honeydew. Long term effected plants may become infected with disease or viruses, the leaves may also turn yellow in random patches. Growth may also become distorted.
Control is really easy and in most cases doesn't require anything more than warm soapy water although theoretically a chemical treatment, in comparison to others it's very gentle.
Mealybugs are related to Scale insects and cause damage by sucking sap from plants. They are reasonably large as far as pests go, resembling furry white woodlice. They cluster together and on first glance you might think you are looking at cotton wool. If left untreated their damage will cause the leaves of the plant to yellow and eventually drop off.
It's very common to be able to spot the insects before you start noticing symptoms on the plant, colonies of mealybugs tend to group on the undersides of leaves and in the leaf joints of plants. The plant will show you it is infested by wilting and generally looking dehydrated, it may be losing leaves quite rapidly. Also look for sticky honeydew residue.
Of all the house plant pests you can come across the Red Spider Mite is arguably the most feared. The damage caused isn't necessarily the worst, but their prevalence and difficultly in removing can be quite trying and frustrating. Like their name suggests they are arachnids and therefore related to normal spiders, however although they spin webs all over your plants they don't feed on flies, instead they eat the liquids found within plant leaves. The webbing is used to protect the colony and basically open up quick access "roads" to different parts of the plant, if allowed to get out of hand you will have a mini metropolis on your hands.
The sticky webbing is one of the most obvious signs these insects have set up home. However the most common symptom on the plant is mottled leaves with lots of little brown dots. This is caused by the spiders piercing the leaf cells with their mouthparts which then causes the cells they've pierced to die and in turns creates this brown speckling effect.
Scale is a tricky pest to identify and can be difficult to eradicate. The insects have a hard outer brown shell that locks them in place a bit like barnacles on a beach at low tide. They are neatly camouflaged because even if you are looking at them directly to the untrained eye you may still think you are looking at a natural blemish on the plant leaf.
Quite simply, sticky honeydew everywhere. If the plant is near a window it will be filthy with it, if near fabric the honeydew will eventually turn black and create almost "sooty" like mould. Look closely at the underside of the leaves or on the stems and you will see them as small round or oblong brown discs.
They are only formidable because of their protective shield, if you can get rid of that then you've almost won the battle already. Although it's rare to eradicate them in one go. Their offspring are very small and mobile therefore easy to miss, in a few weeks they will set up home where their parents once lived. Be prepared to treat the plant several times before they go completely.
There is nothing worse than having small annoying files zipping around. You bat them away to start with, but with their constant distraction you seek out where they are coming from and eventually find a small colony hovering or running around the base of your house plant(s). Fortunately although very common they tend not to harm indoor plants and are therefore more of a nuisance than anything.
Spotting small black flies around 2mm long either flying around near the plant, or running over the soil surface. The larvae are small worm like creatures, up to 1cm long, it's hard to spot them though as they tend to exist just under the soil surface.
In 95% of cases you will only have Slug or Snail problems on plants which you choose to put outside in the warmer months of the year, they can still set up shop in your home too though. They are quite a big pest both in size and with the amount of damage they do in a short space of time, however they are also the simplest to deal with.
Identification is easy. The leaves will be drastically damaged, large holes, or entire leaves stripped clean. When morning comes they will be well hidden, but they will sometimes leave a slimy trail around the area, which is the smoking gun as to what the culprits are.
Springtails are small, white or grey insects that live off the decaying organic matter found in soils. They are small (although can be seen easily with the human eye as they stand out against the dark compost) and best resemble fleas, they aren't really pests at all as they do no damage. However their presence often attracts attention because when you water and are consequently paying more attention to the plant than usual, the water triggers the Springtails to go wild with movement and thereby alerting you to their existence.
When you water the plant and it hits the soil, you will notice small white flea like insects jumping or moving around.
As above there isn't really a need for a "treatment", but they can be frustrating.
Photo credit of the Red Spider Mite close up Gilles San Martin
Photo credit of the Mealybug Forest & Kim Starr
Photo credit of the Red Spider Mite Harald Hubich
Photo credit of the Fungus Gnat Erik Burton
Photo credit of the Springtails Marshal Hedin