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Common houseplant pests and how to get rid of them

Common houseplant pests and how to get rid of them

We plant parents are super proud of our leafy babies, so it’s only natural we worry when they get sick. Yellow leaves, shedding foliage or a whole lotta droop…they can all spell trouble! While it may be a matter of too much (or too little) water or light, in some cases it may suggest something a little more sinister... pests! 

But wait?! How do these plant pests get onto my indoor plants?

These pesky critters hitchhike into your home on newly purchased plants or plants that have been vacationing outside, they can hide out in soils and potting mixes or catch a lift with your beloved hairy dog. But don’t stress! You don’t have to live in fear of these miniature menaces. We’ve made a list of common houseplant pests and how you can give them the boot!

Mealybugs

What do they look like and what do they do?

Mealybugs are tiny, grey oval shaped insects that are covered in a white powdery coating. They love hiding beneath leaves and in grooves where leaves meet stems. The most obvious sign of mealies is a white cotton-candy looking substance. Baby mealies (or crawlers) scope out healthy plants looking for a good place to feast and then they set up camp, growing a fluffy, white coating to protect them from predators. Sneaky hey? 

These fuzzy little vampires set up home in your plant’s foliage and then suck the life from them. It starts out as patches of fluff here and there, but you can’t miss a mega infestation. It’ll look like white cotton wool covering your plant. As they multiply, they cause stunted growth, yellowing, and sick looking foliage on your indoor plants.

They can be trickier to spot in smaller numbers, but if you’re sharp-eyed you might spot small line-like scars on leaves or see a sticky brown substance on the leaves. This sticky stuff is actually mealy poop (or honeydew). It’s called ‘honeydew’ because (prepare your stomach) it’s sweet and ants love the stuff. So don’t be surprised to find ants hanging around snacking on the sweet stuff if you have a mealy infestation!

Here is a guide to treating a mealy bug infestation.

 

A close up of mealy bugs infestation on a plant stem

Thrip

What do they look like and what do they do?

Thrips (also known as thysanoptera or thunderflies) are tiny, slender critters with narrow wings. They’re so small they look like tiny moving slivers on your plants. They can range in colour from white or yellow, to black or brown. The younger thrips (nymphs) are even smaller and are usually light green or yellow. 

There are around 7,400 species of thrip in the world (yikes!), but the most common offenders are greenhouse thrip (Heliothrips haemorrhoidalis), western flower thrip (Frankliniella occidentalis) and plague thrip (Thrips imaginis).

These guys like to poke holes in leaves, flowers and other plant parts and suck out the juices. Thrips can also spread plant viruses; for example tomato thrips and western flower thrips are huge spreaders of the tomato spotted wilt virus.

If you disturb the plant, they will likely hop or fly away, so keep an eye out for thrip damage. Be on the lookout for streaks, silvery speckling, and small mottled white patches. If you have a major thrip infestation, your plant might look stunted with damaged flowers/fruit.

 

A magnified view of thrip pest on an indoor plant

Fungal gnats

What do they look like and what do they do?  

Fungal gnats are little flies with slender dark bodies and wings (they are often mistaken for fruit flies), and they eat – yup, you guessed it – fungi. They also feast on the organic matter in the soil and algae, which can build up in pots. Fungal gnats are all about warmth and humidity. They prefer temperatures between 17-25°C, which (unluckily for us) is the temperature of most Australian households. A damp plant pot in a warm home is the perfect breeding ground for fungal gnats. 

A close up view of a fungal gnat

Fungal gnats are super common and have an irritating habit of hovering around your face. That’s because they love the carbon dioxide you’re breathing out. While adult fungal gnats are incredibly irritating, they don’t do much damage to your plants. They can, however, spread nasty fungal diseases like Fusarium, Pythium, Phytophthora and their babies are certified plant killers.

Fungal gnats are a common problem but fortunately treating fungal gnats and preventing further infestation is achievable. This fungal gnat treatment kit will help stop these unwanted pests. 

Adult gnats lay around 300 eggs in their short lifetime, and those develop into squirmy larvae (hope you’re not eating right now). Fungal gnat larvae munch on the fine root hairs of your plant babies causing some serious plant damage and stunted growth. These little guys can be hard to spot because they look just like fine almost transparent plant roots burrow into your soil (see if you can spot one in the image below). In about four weeks these larvae grow wings and fly the nest. So you can see how gnat infestations quickly get out of hand. 

Learn more about fungal gnats and how to get rid of them.

A hand holding some soil with a magnified view of fungal gnat larvae

Spider mites

What do they look like and what do they do??

Spider mites are tiny little  mites that can often be seen crawling quickly across the surface of leaves and stems. Despite their name, spider mites aren’t actually spiders (though they are distantly related). They got their name because they look a lot like their arachnid cousins and they also weave webs. 

These little buggers love hot, dry air and unfortunately, they love indoor plants.

They find healthy looking plants and then use their little fangs to slurp up the fluid. The most obvious way to tell if you have a spider mite infestation is thin, stringy webbing running between leaves, or petals.

If spider mites are left to put up streamers and party for too long, they will cause brown or yellow spotting on your leaves or patchy discolouration on foliage and start to look a bit distorted.

A close up view of spider mites on a houseplant

Scale

What do they look like and what do they do?

Scale are a small, oval shaped bug with a protective white/translucent to brown shell-like covering. They lay flat on your plant and suck the sap from your pals.

Unlike many of the above critters, scale are immobile once they find their home. They lock themselves into place and begin feeding on sap, so no chasing bugs around for you.

These clever little ones protect themselves with their hard exterior shield, so wiping or gently scratching off these pests as soon as you spot them is the first step to treatment.

A magnified view of the common pest scale on the leaves of an indoor plant

 

How to get rid of ‘em?

Okay so you’ve identified some creepy crawlies on your houseplants and you want to get rid of them. When it comes to houseplant pests, it’s better to act sooner than later. Here's what todo.... 

Step 1: Isolate

Move the affected houseplant away from other plants to stop the spread. Check your other plant babes for any signs of damage and if needed, isolate them too.

Step 2: Wipe

Arm yourself with a damp cloth and wipe off as many of the critters as you can. If you’re dealing with mealybugs wipe off any visible honeydew, fluff or mealies. If it’s spider mites, wipe away any mites or webbing that you can see. The same goes for fungal gnats and thrip (though these guys will usually jump/fly away).

Carefully inspect your plant and wipe away any stragglers (making sure you check the undersides of leaves).

Step 3: Oil

Use neem oil (a natural insecticide) to kill any remaining bugs, eggs or larvae. Dilute some concentrated neem oil with the recommended amount of water, a few drops of organic dishwashing liquid (so the oil sticks) and transfer to a spray bottle. Spritz your plant liberally, covering all the leaves and allowing it to soak into the soil. 

Repeating steps 1-3 will usually be enough to stop any crawlies, but if you have a pest infestation, you might need to take further steps. 

An open box with several pest control products for plants inside

Step 4: Repot

Mealybugs, thrip and fungal gnats can lay eggs in potting mix that will later hatch out and BOOM! More crawlies. So if you have an infestation, it’s best to re-pot. You can use a brand new pot or sterilise your old pot before re-potting. Be sure to use fresh, quality potting mix (as cheap ones can have pests living inside them already). It is good to note that potting mix can go off and your soil may be riddled with fungal gnats, so check the bag and always store in a sealed container when not in use.

Gently shake all the old potting mix from your plant’s roots and put the contaminated soil into the bin. Make sure you do this away from your other babes because thrip, gnats and male mealybugs can fly. Rinse the roots with your already made up neem oil, dishwashing liquid, water mix.

Now re-pot your plant and always wait for your plant to dry out before re-watering. Stick your finger about an inch into the soil mix, and if it feels dry, break out the watering can. Always allow your plants to drain after watering (we sound like your mum now don't we?)

Step 5: Watch

Keep an eye out for more critters over the next few days. Some escapees may re-appear and if that happens, use your trusty neem oil again, repeating each week until they’re gone. 

Step 6: Protect

Once you think you’re pest free, protection is key. Pour a layer of canna aqua clay balls, gravel or coir fibre matting over the top of your potting mix to deter pests from laying their eggs in your potting mix. It acts as a shield! 

A small stack of coconut coir mats on table next to a houseplant

Hasta la vista, pesties!

Just remember if you find pests on your plant babies, it doesn’t mean you’re a bad plant parent. If you find houseplant pests, keep calm and crack down. Keeping your plants healthy means that they are more able to deal with those pesky critters.

Whether you have pests on your houseplants, or just want to be prepared, you can’t go wrong with our trusty Eco Trio Pack. All 100% organic, pet safe and kid safe!

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