Summary
Ottawa's summer heat and humidity create ideal conditions for three houseplant pests: spider mites, fungus gnats, and mealybugs. This guide walks through how to tell pests apart from overwatering or heat stress, how to treat each pest without harsh chemicals, and when it's actually time to let a plant go.
From Terra Flowers & Flavours, Ottawa's flower shop, café, and plant boutique in Barrhaven.
Key Highlights
- Not every sick-looking plant has bugs. Overwatering and heat stress cause similar symptoms and need different fixes
- Spider mites thrive in hot, dry air, which is exactly what Ottawa homes get in July
- Fungus gnats are a soil problem, not a plant problem. They mean the soil is staying too wet
- Mealybugs show up as white, cottony clusters in leaf joints and stem crevices
- Isolating an infested plant immediately is the single most important step, before any treatment
- If treatment fails after two to three weeks, it's usually cheaper and less frustrating to replace the plant than keep fighting it
Ottawa homes get sticky, humid, and hot in July, and houseplants feel it too. If your plant suddenly looks off, speckled leaves, tiny webs, sticky residue, or little flies buzzing out of the soil, it's easy to assume the worst. Sometimes it really is bugs. Sometimes it's just the heat, or a watering habit that needs adjusting.
Terra Flowers & Flavours is Ottawa's flower shop, café, and plant boutique in Barrhaven, and this is one of the most common questions customers bring in during the summer months. Here's how to actually tell the difference and what to do about it.
What's Actually Wrong With My Plant?
Before treating for bugs, rule out the two things that get mistaken for pests most often: overwatering and heat stress. Both can cause yellowing, drooping, or spotted leaves that look a lot like pest damage at first glance.
Check the soil first. If it's been wet for more than a few days and the plant is yellowing from the bottom up, that's overwatering, not bugs. If the leaves are crispy at the edges and the plant is sitting near a hot window or air vent, that's heat stress. Bugs tend to leave more specific evidence: webbing, sticky spots, cottony clusters, or tiny moving specks you can actually see.
- Yellowing from the bottom up with wet soil usually means overwatering
- Crispy, browning leaf edges near a hot window usually means heat stress
- Fine webbing, sticky residue, or visible insects usually means an actual pest
A simple way to check for pests specifically: hold a plain white sheet of paper under a leaf and gently tap the leaf. If tiny specks fall onto the paper and start moving, you're dealing with an infestation, not just environmental stress.
What Are the Most Common Houseplant Pests in Ottawa Right Now?
Hot, dry indoor air combined with summer humidity swings creates ideal breeding conditions for a few specific pests. These three show up the most in Ottawa homes this time of year.
Spider Mites
Spider mites love hot, dry conditions, which is exactly what a lot of Ottawa homes have in July, especially near sunny windows or air conditioning vents. Look for fine, almost invisible webbing between leaves and stems, along with small yellow or white speckling on the leaf surface. In bad cases, leaves take on a dusty, dry look before dropping.
Spider mites are one of the fastest-spreading houseplant pests, so isolate the plant from others as soon as you spot them.
Fungus Gnats
Fungus gnats are small black flies that hover around the soil surface, especially when the pot is disturbed. They're a sign the top layer of soil is staying too wet for too long, often from watering on a fixed schedule instead of checking the soil first. The adult flies are mostly harmless, but the larvae in the soil can damage roots over time.
The fix here is almost always about the soil, not the plant. Letting the top inch or two dry out fully between waterings breaks the gnats' breeding cycle.
Mealybugs
Mealybugs look like small clusters of white cotton tucked into leaf joints, along the stem, or underneath leaves. They feed on plant sap and leave behind a sticky residue called honeydew, which can attract ants or develop black sooty mold if left untreated.
Mealybugs move slowly but spread through direct contact with other plants, so check anything sitting nearby.
- Spider mites: fine webbing, speckled leaves, worse in hot dry spots
- Fungus gnats: small flies over the soil, tied to overwatering
- Mealybugs: white cottony clusters in leaf joints and stem crevices
How Do I Get Rid of Houseplant Pests Without Harsh Chemicals?
Most common houseplant pests can be treated without strong pesticides, especially if you catch them early.
For spider mites and mealybugs, wiping leaves and stems with a cotton swab dipped in diluted rubbing alcohol kills what you can see on contact. Follow up with a full-plant spray of neem oil or insecticidal soap, covering the undersides of leaves where pests hide. Repeat every five to seven days for two to three weeks, since these treatments kill on contact but don't stop eggs from hatching. For fungus gnats, skip the sprays and fix the watering habit instead. Let the top one to two inches of soil dry out completely before watering again. Yellow sticky traps placed in the soil catch adult gnats and help you track whether the population is actually shrinking.
- Isolate the plant from others the moment you spot a pest
- Treat every five to seven days, not just once, since eggs survive the first treatment
- For fungus gnats, changing the watering habit matters more than any spray
If you're not sure whether your soil is actually staying too wet or you just haven't checked in a while, a moisture meter takes the guesswork out.
When Should I Just Let a Plant Go?
Not every infestation is worth fighting. If more than half the plant is affected, if the main stem or crown is compromised, or if you've treated consistently for three weeks with no improvement, it's usually more practical to let the plant go and start fresh than to keep pouring time and product into it.
This isn't a failure on your part. Some plants are simply more prone to pests than others, and a small, inexpensive replacement is often the better trade than months of ongoing treatment.
- Severe infestation covering most of the plant: consider replacing
- No improvement after three weeks of consistent treatment: consider replacing
- Damage limited to a few leaves you can remove: usually worth continuing treatment
What Are the Best Beginner-Friendly Plants That Resist Pests?
If you're replacing a plant or just want something lower-maintenance going forward, some houseplants are naturally more pest-resistant than others. Thick, waxy leaves are harder for spider mites to latch onto, and simpler leaf structures make it easier to spot problems early.
ZZ plant and snake plant are two of the most pest-resistant beginner plants available, thanks to their thick, waxy leaves. Pothos is a close third, easy to inspect since its leaves hang in the open rather than clustering tightly like some tropical plants do.
- ZZ plant and snake plant: thick, waxy leaves that are naturally harder for pests to target
- Pothos: trailing leaves make it easy to spot and treat problems early
- All three tolerate irregular watering, which also lowers fungus gnat risk
Frequently Asked Questions About Houseplant Pests
How do I know if my plant has bugs or is just overwatered?
Check the soil first. Overwatering usually causes yellowing from the bottom of the plant up, with soil that's been wet for days. Bugs leave more specific evidence like webbing, sticky residue, or visible insects you can see with a white paper tap test.
What is the easiest way to check for spider mites?
Hold a white sheet of paper under a leaf and gently tap it. If tiny specks fall onto the paper and start moving, that's spider mites. Fine webbing between leaves and stems is another clear sign.
Do fungus gnats mean my plant is dying?
Not usually. Fungus gnats mean the soil is staying too wet, not that the plant itself is failing. Letting the top inch or two of soil dry out between waterings usually clears them up within a few weeks.
Can I use dish soap instead of insecticidal soap?
Diluted dish soap can work in a pinch, but true insecticidal soap is formulated specifically for plant leaves and is less likely to cause leaf burn. If using dish soap, dilute heavily and test on one leaf first.
How long does it take to get rid of houseplant pests?
Plan on two to three weeks of consistent treatment every five to seven days. Sprays kill visible pests but not eggs, so a single treatment is rarely enough.
Should I throw away a plant with a bad infestation?
If more than half the plant is affected or the main stem is compromised, replacing it is often more practical than continuing treatment. A small, inexpensive replacement can save weeks of ongoing effort.
Terra Flowers & Flavours is Ottawa's flower shop, café, and plant boutique in Barrhaven.
Open Mon-Sun 9:30am-7pm.
Call 613-440-0033.
Same day delivery across Ottawa, Barrhaven, Kanata, Nepean, Manotick, and Orleans.