Pepper Pests in the Greenhouse and How to Combat Them

Peppers face a huge onslaught from destructive insects, many of which are dangerous and capable of wiping out the entire crop in just a few days.

To prevent such a catastrophe, it’s crucial for you to identify and combat these vegetable foes promptly.

Peppers are incredibly tasty and nutritious, packed with vitamins and minerals. Unfortunately, it’s not just us who appreciate them, but also numerous pests that annually destroy part of the greenhouse pepper harvest.

Today, I’ll discuss the most dangerous and teach you how to deal with these little troublemakers.

1- Whiteflies

My grandma finds it tricky to spot this tiny insect as she often helps me in my greenhouse. 

Despite the striking appearance of the adult insects (four snow-white wings that seem dusted with flour), the whitefly is a secretive and cautious pest.

Its body is only 3-5 mm long and light yellow in color, and it spends most of its time hiding on the underside of leaves.

Inexperienced gardeners often confuse whiteflies with moths, which scurry quickly when disturbed and only then take flight.

The insect’s larvae are even smaller and resemble transparent blisters or growths. In the greenhouse or glasshouse, whitefly attacks peppers.

You might discover them accidentally – for instance, you could shake a leaf and see a swarm of tiny flies take off and start swirling around the plants.

The underside of the leaves becomes sticky and is covered with small light spots – traces of the parasite’s excretion (honeydew).

Honeydew is full of nutrition for a fungus to thrive, leading to the leaves’ damage; they turn white and yellow (like chlorosis), then suddenly darken and die.

Thus, the pepper plant’s death isn’t the insect but the fungal and infectious diseases it carries and triggers (powdery mildew, mosaic, gray rot).

Combating Whiteflies:

1. During winter, maintain a cool temperature in the greenhouse (around 53-57 °F for 3-5 days will kill the insects) and disinfect the area by burning sulfur candles for 6-8 hours. Afterward, remove and dispose of the top layer of soil where the larvae hide.
2. Mechanical removal: Wash off the larvae and insects with water from watering hoses, wipe the leaves with a soapy solution, and use a vacuum cleaner to catch flying insects that have taken to the air.
3. Create yellow and bright blue sticky traps. You could take a sheet of plywood, paint it light yellow or blue, and apply a sticky substance. Rinse off the trapped whiteflies with a soapy solution and reapply the sticky substance.
4. Biological methods: Introduce ladybugs and lacewings into the greenhouse or prepare a special herbal infusion. Crush a head of garlic and soak it in about 2 cups of water. Let the mixture sit for about a week. Dilute the prepared solution in a ratio of 5g per 1 liter of water and spray all the plants in the greenhouse.
5. If dealing with a whitefly infestation spiraling out of control, I reach for reliable solutions like insecticidal soaps, neem oil, or natural insecticides like Pyrethrins. But if I’d prefer not to use any sprays, I’d call in Mother Nature’s own pest control – ladybugs. These beneficial bugs do an incredible job battling whiteflies in my greenhouse, particularly on my pepper plants.

2- The Colorado Beetle

Who isn’t familiar with this ‘striped saboteur’? Of course, its primary dish is potatoes, but in lean times, it doesn’t shy away from pepper plants either.

Adult beetles are easily recognized by their black-and-white shell and yellow thorax with black dots, measuring 7-12 mm long.

The larvae are larger, up to 15 mm, dark brown, gradually lightening to an orange or pinkish hue. Spotting a Colorado beetle is easy, but defeating it is much more challenging.

To this day, no 100% effective protection method has been developed – the beetle quickly becomes resistant to chemicals, effortlessly survives cold winters, and is not a delicacy for birds and predatory insects.

In the initial stage, bright yellow egg clusters (a single female can lay up to 1000 eggs in a season) can be found on the underside of the leaves.

Subsequently, you can observe larvae dutifully gnawing at leaves, shoots, and leaf tips.

Adult beetles, which live for 1 to 3 years, are also caught in the act. Instead of a pepper bush, a gnawed ‘skeleton’ is left behind.

Combatting the Colorado beetle:

1. Collect egg clusters, larvae, and beetles from your pepper plants and destroy them by pouring kerosene or formalin. Don’t crush the beetles – the smell attracts ‘avengers’ from other areas.
2. Plant garlic and marigolds near your pepper plants – their scent repels the Colorado beetle.
3. In the middle of the summer, when bugs usually lay their eggs, pile up soil around the base of your young pepper plants until it covers the lower leaves. This is called ‘high hilling.
4. Mix a glass of ash and 5- 7 ounces (150-200g) of crushed wormwood with 2.5 gallons (10 liters) of hot water. Let it infuse for 2-3 hours and then strain. After this, spray the pepper bushes with the solution.
5. If the Colorado beetle infestation overwhelms, consider using safer, garden-friendly insecticides like Monterey Garden Insect Spray. Weekly insecticide spraying can help prevent insect population growth and offer robust protection.

3- The Mole Cricket

There’s no mistaking this “mole of the insect world” for anything else. This small insect’s repulsive and intimidating appearance, which can measure up to 3 inches (8 cm) in length, terrifies anyone seeing it for the first time.

Its robust exoskeleton that covers its head and chest, a pair of long wings, burrowing limbs, and a split “tail”—this is the mole cricket, the perpetrator behind the demise of countless crops.

The mole cricket retreats underground at the first sign of danger or approaching cold weather. Down there, it has everything it needs: food, warmth, and a sense of security. 

Identifying plant damage isn’t easy as the mole cricket feeds on the underground part of pepper plants and can snack on 10-15 plants daily.

This creature is usually detected by its winding burrows, which weave from plant to plant and have entrance holes.

Not only does the mole cricket fly and swim exceptionally well, but it also doesn’t mind dining on other vegetables and even wouldn’t pass up an earthworm meal. Getting it off your property is not a simple task.

How to Combat the Mole Cricket:

When preparing manure, soil, compost, and other mixtures intended for greenhouses, scrutinize them carefully, removing any mature pests you find. Regularly weed out your greenhouse.

During the mole cricket’s flight period in May, use light traps consisting of a lamp and a container with a water-kerosene emulsion. Mole crickets are drawn to the light source, collide with it, and fall into the liquid.

Seek out nests, egg-laying sites, and young larvae from late May to early June. Collect them manually or simply keep your soil constantly loose.

Treat the mole cricket’s discovered tunnels with a soap solution (2.5 ounces per gallon of water). Use up to 2  gallons per square yard to soak the soil 3-4 inches deep.

4- Ants

We usually admire these highly organized creatures until they start wreaking havoc on our plants and stores.

Garden ants are attracted by aphid secretions and even the pepper plants themselves. These ants become “shepherds,” guarding the aphids on the plants and feasting on their sap.

So, you can’t really get rid of the aphids without also tackling the ant colony that’s thousands strong.

Neither ants nor aphids are particularly good at hide-and-seek—you can spot a plant they’ve taken over easily.

Most of the damage from ants comes from how they multiply and protect aphids, but don’t be fooled; they’re not innocent either.

They have a knack for wrecking our gardens, messing up flowerbeds, and even sipping on plant sap themselves. If ants have invaded your garden, brace yourself for a long war.

Fighting Ants:

1. Find and destroy the ant queen, then ransack the anthill (if there’s only one in the garden), dump it into a bucket, and carry it well beyond your garden limits.
2. Stir up the anthill with boiling water, kerosene, or hot ashes. You can also add a poison solution – 2 cups of vegetable oil, 2 cups of shampoo, and 2 cups of vinegar to 2.5 gallons of water. Drill a hole in the center of the anthill and pour in the prepared mixture, then cover it with plastic for a few days.
3. Prepare “humane” traps – regularly placing jars near ant trails with water, honey, sugar, or meat scraps – the ants crawl into the jars and can’t escape.
4. Make poisonous baits: 2 tablespoons of ground meat and 1/2 teaspoon of boric acid. Or this one: 2 tablespoons of hot water, 1 tablespoon of sugar, 1/3 teaspoon of boric acid, and 1 tablespoon of honey (after it cools down).
5. If all else fails and you’re dealing with multiple anthills and a large colony in the millions, resorting to chemical treatments might be your best option. Personally, I found that Raid Multi Insect Killer worked remarkably well for this purpose.

5- Nematodes

Those microscopic worms we call nematodes often get blamed for messing up our pepper plants.

These little buggers, barely visible to the naked eye, spend their entire lives underground.

We usually don’t even notice they’ve set up camp until it’s too late—they’ve had their feast, done their thing, and hit the road.

At first, your plants will start to look a bit peaky—like they’re not getting enough water or food. Stems start to droop, leaves turn yellow, and growth might slow or even stop.

And then we say, “Ah, shoot. Bad harvest this year,” as you dig up what’s left of the plants.

It’s then that we find the roots are thin like thread, and there are these weird brown and yellow bumps on them—dead giveaways that our uninvited nematodes were the culprits. Sadly, by then, it’s too late to save the plants.

Now, if you’re looking to tackle these nematodes, here’s what I’d suggest:

1. Drench your soil with boiling water, going as deep as 16-20 inches, then cover the surface with a plastic sheet for 3-4 hours.
2. Peel away a layer of soil about 16-20 inches deep and replace the infected dirt with healthy soil.
3. Use disinfected tools and clean planting materials – the roots of your seedlings should have no growths or swellings (which could be larvae containers).
4. If you spot the presence of nematodes early on, clear the plant roots from the soil and immerse them in water at a temperature of 122-140°F. The worms will meet their demise within 5 minutes, but you must keep the pepper roots in hot water for around half an hour to annihilate the eggs.

6- Spider Mites:

Let me introduce you to another “invisible” nemesis in the world of pepper gardening – the teeny, tiny spider mite.

These microscopic arachnids grow to a mere 0.3-0.5 mm in length, and their semi-transparent bodies seem perfectly designed for camouflage, making them really tricky to spot on your plants.

If you start to see barely noticeable red or orange dots, that’s your clue that mites have made themselves at home on your peppers, or any other crops for that matter.

As they suck all the sap out of the plant, these mites turn a more noticeable color when fall rolls around.

More often than not, you’ll discover the presence of mites through the telltale signs they leave behind.

Fine spider webbing starts to appear on the underside of the leaf, and before long, the entire plant – stem, leaves, and flowers – becomes covered with small yellowish dots.

Eventually, the mites weave their webs all over the plant and slowly march toward death.

Spider mites are quite the little hitchhikers, moving from infected plants to healthy ones, catching a ride on the breeze, coming in with the soil, and even turning your clothes into their temporary “base.”

But don’t worry; I’ve got some tactics to fight back against spider mites:

1. Keep humidity high, and make a habit of regularly spraying the outer sides of the pepper leaves. This simple step can go a long way in preventing a mite invasion.
2. If you spot any signs of mites, don’t hesitate to water your plants generously with warm water, adding 2 grams of kerosene and 40 grams of soap to 2.5 gallons of fluid. Isolate any plants showing signs of damage right away.
3. Try a tobacco infusion as an effective homemade solution: Add 400 grams of raw tobacco to 2.5 gallons of water and let it steep for a day. Boil this concoction for 2 hours and after it cools down, add another 2.5 gallons of water and 50 grams of soap. Spray this evenly onto the leaves.
4. For a store-bought solution, you can spray the plants with treatments like Mite Control insecticide. If you prefer a natural option, I’ve found that Southern Ag Natural Pyrethrin works great.

7- Garden Slugs

“Well, here’s a real menace!” you might say. They can’t fly, their jaws are weak, and their movement is painfully slow.

Pick up some of these slimy pests, and voila – your harvest is saved, right? But let me tell you, these slugs are real gluttons, leaving a sticky trail everywhere they go.

They might not munch through your plants, but their slime can suffocate leaves.

With their soft, elongated bodies reaching 50-60 mm in length, these mollusks are night crawlers, so their activity often goes unnoticed. They thrive in dense plantings, high humidity and love tender leaves.

Here’s how you can recognize the damage they do: right in the middle of leaves (less often on the edges), you’ll see round holes they’ve chewed through.

The presence of slugs in your garden can also be indicated by slime trails and excrement.

During the day, you should look for them under plant debris on the ground and in cracks in the soil.

Slugs have one terrifying enemy – temperatures above 27°C (80°F). Below, we’ll talk about other measures to control these pests.

Fighting Garden Slugs:

1. Start by tidying up your garden – remove all weeds, mow the grass, and destroy piles of old grass and any plant debris.
2. Dig trenches between your planting rows and fill them with lime, ash, crushed black pepper, or tobacco dust. Slugs won’t cross such a “moat.”
3. Consider covering your peppers with plastic. Slugs will crawl under it at night, but during the day they’ll perish from the unbearable heat. You could also pour water heated to 40-50°C (104-122°F) over the slugs during the day.
4. Sprinkle the soil with quicklime after rain or a heavy watering when slugs begin to move. The lime burns the slugs’ bellies, causing them to die.
5. The go-to product for combating slugs in the most effective way is Sluggo, especially if you have pets and kids in your household.
6. I’ve experimented with crushed eggshells, and it worked well! I scattered some crushed eggshells around my plants, and it kept away the slugs from reaching my peppers plants.

8- Cutworms

Believe it or not, there are more than 100 species of cutworms out there, and it’s quite possible one or more of them have found a home in your very own garden.

Do you know that seemingly innocent moth that paid a visit, drawn in “like a moth to a flame”? Well, it might just be a garden cutworm in disguise.

This hard-to-spot moth, sporting a wingspan of just 0.4-0.5 cm, boasts dark brown wings decorated with a faint gray wavy line and a smattering of 4-6 small bud-like dark orange and gray spots, all encircled by a white border.

This moth’s tree-like camouflage makes it a challenge to spot, even in the evenings, and by day, it stays hidden.

As for the cutworm caterpillar, it’s a vibrant green with a side stripe that’s lettuce-colored and crossed lines on its back. Just like the moth, it only surfaces at night.

When it comes to damage, it’s the usual caterpillar fare – leaves chewed at the edges and occasional fruit damage.

Cutworms are most active during summer, and in warmer southern regions, you might see two generations in a single season.

Battling Cutworms:

1. Keep your garden weeded, particularly of flowering plants. These serve as nectar stations for butterflies, and their absence can lead to the depletion of adult cutworms. Plus, cutworms are known to lay their eggs on plants like bindweed, nettle, and Milk thistles, so it’s best to get rid of these too.
2. You can manually collect caterpillars, but bear in mind this is a nighttime job, which might not always be convenient.
3. In winter, consider tilling the soil. Cutworm caterpillars hibernate deep down, up to 8 cm (around 3 inches). So, loosening and turning over the soil between rows after the caterpillars have cocooned can help reduce their numbers.
4. Get creative and build homemade traps out of cut plastic bottles. Hang them about a meter (around 3.3 feet) above the ground and fill them up to a third of the bottle’s height with molasses. For bait, any fermented jam or fruit juice will do.
5. As for chemical solutions, one of the most effective insecticides is Monterey Garden Insect Spray. 

9- Aphids

Imagine a tiny bug no larger than 0.5-0.7 mm, with a miniature proboscis, having a taste for plant sap. One such insect? No big deal. But a colony of 20,000?

Now that can reduce your lush greens to mere dry “skeletons”. Plants under an aphid attack rarely recover.

Open wounds on them invite various infections and fungal diseases, which finish off the plants. The result? A total loss of the crop.

Aphids are like magnets for other pests, notably garden ants. Thus, the first thing you’ll likely notice is plants swarming with ants.

The damaged leaves curl, the shoots dry up, growth halts, and the tips curl. The stems and leaves are left with sweet secretions, which attract ants.

By the way, if you manage to shoo away the aphids, you’ll complicate life for the ants too.

Battling Aphids:

1. Natural enemies of aphids include ladybugs, lacewings, and hoverflies. A ladybug can munch on up to 100 adult aphids a day. To attract this “savior,” plant dill, cumin, coriander, and fennel in your pepper beds. Containers with wood shavings will attract the earwig, another big “aphid fan.”
2. Follow good cultivation practices for growing peppers. Add optimal amounts of nitrogen, phosphorus, potassium, and trace elements. Good air circulation and timely watering make plants healthier and less attractive to aphids.
3. For home remedies, we recommend tobacco and ash. Fill a 2.5-gallon (10-liter) bucket with a cup of wood ash and tobacco dust, and pour in hot water. After a day, strain the solution and add a tablespoon of liquid soap. Spray this mixture on your plants every morning.
4. Take 9 ounces (250 grams) of finely chopped garlic and pour half a gallon (2 liters) of boiling water over it. Let it sit for a day, filter it, and add 20-30 grams of soaked household soap. Then, fill up with water 2 gallons (8 liters). For spraying, use half a gallon (2 liters) of this concentrate diluted in (2.5 gallons)10 liters of water.
5. As a last resort,  If you prefer a natural option, I’ve found that Southern Ag Natural Pyrethrin works great.

10- Thrips

Also known as thysanoptera or fringe-winged insects, thrips are tiny critters (0.02-0.06 inches) with elongated bodies and striped abdomens.

Their heads have an unusual cone-like shape that looks like it has been cut off at the bottom. Their antennae are small and distinctly segmented.

The fringe on their two pairs of wings, resembling tiny hairs, gives them their name. These insects are recognized by their distinctive flight patterns, seemingly flitting from one plant to another.

It’s tough to spot them in your garden because these small, semi-transparent pests can easily be mistaken for plant seeds or specks of dust.

Both thrips larvae and adult insects suck the cellular sap from plant tissue. In these areas, yellow or faded spots, streaks, or lines appear on the surface of the leaves, which eventually die off, and the leaves fall.

Thrips feast on nearly all plants and, in the process, transmit diseases that are harmful to peppers.

Combatting Thrips:

1. Give your plants a “shower” periodically – wash off larvae, and adult insects, with a strong stream of water.
2. Set up yellow sticky traps between your plants – this will help reduce the pest population.
3. You can use a marigold infusion – fill a container half full with crushed, dried marigolds, top it up with warm water, and let it sit for two days. Then strain the concoction and spray it onto your plants.
4. Dilute 1 tsp of crushed onion or garlic in a cup of water. Let it steep for a day, then spray your plants with the mixture.
5. For commercial solutions, Neem oil, insecticidal soaps, and horticultural oils are effective against aphids.

Defending your peppers against pests can be a challenge. Given that peppers are a tempting target for most common “crop marauders,” the secret to successful defense lies in spotting them early and acting swiftly to remove them.

Armed with these strategies, among which some of them have worked hard, you’ll be well-prepared to safeguard your peppers from any threat.