Pests

1.1 Sucking Pests

These pests feed on plant sap by piercing leaves, stems, or fruits and sucking out the cell contents. Their impact is not immediately obvious but is extremely dangerous because they drain the plant’s vitality and often transmit viruses.

What does the damage look like?

• Leaves curl downward like a “boat” or “spoon,” becoming puckered and deformed (Bosland and Votava, 2012). This classic symptom points to aphid infestation.
• A sticky, shiny coating (honeydew) appears on leaves and stems. This is the sugary excrement of insects, mainly aphids and whiteflies. Sooty mold soon grows on this coating, covering leaves with a black film that further disrupts photosynthesis (Rêgo et al., 2016; Welbaum, 2015).
• Leaves are dotted with tiny pale spots (“puncture marks”), which merge under heavy infestation, making the leaf appear marbled, then yellow and withered. This is typical of the spider mite, which also leaves a fine, barely visible webbing on the underside of leaves (Rêgo et al., 2016).
• Young leaves and shoots become wrinkled with curled edges, and plant growth slows. This is also characteristic of aphid colonies that concentrate on growing points (Russo, 2012).
• Fruits and leaves take on a bronze or silvery tint, and irregular-edged spots appear. This may be caused by thrips. Severe infestation deforms the fruit (Kemble, 2022).
• Leaves turn pale, yellowing between the veins, and the plant looks stunted. This is a general consequence of sap loss, typical of whitefly and aphid damage.

Why are sucking pests dangerous beyond sap loss?

Unlike chewers, they cause “hidden” damage. Weakened plants become more susceptible to diseases. But the greatest threat is viruses. For example, aphids and whiteflies are major vectors of dangerous viral diseases such as Cucumber Mosaic Virus (CMV), Potato Virus Y (PVY), Tobacco Mosaic Virus (TMV), and Tomato Yellow Leaf Curl Virus (TYLCV), which can destroy up to 100% of the crop (Rêgo et al., 2016; Bosland and Votava, 2012).

Tip: Inspect the undersides of leaves. That is where aphid colonies, whitefly nymphs, and spider mites hide.

1.2 Chewing (Leaf-Chewing) and Boring Pests

These pests cause more visible and obvious damage – they literally eat parts of the plant. They are easy to spot by the mechanical injuries.

What does the damage look like?

• Leaves have ragged, irregular holes, chewed edges, or the entire leaf blade is consumed. This results from feeding by caterpillars of various cutworms (garden, cabbage), as well as Colorado potato beetles and their larvae (Swiader, 1992). Young caterpillars often skeletonize leaves, leaving only the veins.
• Fruits show gnawed holes, tunnels, or simply eaten flesh. This could be caterpillars of cutworms (cotton, tomato), European corn borer, or tobacco whitefly (adults are suckers, but their caterpillars are chewers).
• Young seedlings are cut off at ground level or have damaged roots. This is the work of soil pests such as wireworms (click beetle larvae) or mole crickets.
• Leaves have “mines” – long, winding white or transparent trails (tunnels). This is a hallmark of leafminer flies. Their larvae burrow inside the leaf blade (Russo, 2012; Rêgo et al., 2016).
• Large leaves are eaten from the edges or between veins, showing characteristic feeding marks. This may be from adult beetles (e.g., Colorado potato beetle or locusts) and large caterpillars (hawkmoths) (Bosland and Votava, 2012).

Why is it important to distinguish between sucking and chewing pests?

Because the choice of control measure depends on it. For instance, systemic insecticides work better against suckers, while stomach poisons work better against chewers. Some biological products (e.g., those based on the bacterium Bacillus thuringiensis, or Bt) are effective only against caterpillars and completely useless against mites or aphids. Knowing the pest type allows you to choose the right protection strategy (Rêgo et al., 2016).

1.3 Hidden (Internal) Pests

This is the most difficult group to diagnose. The pest is inside the fruit, stem, or root, and you notice its presence only after the damage has already occurred.

What does the damage look like?

• Young buds and ovaries turn yellow and drop off, even though the plant looks healthy. This may indicate that the pepper weevil (Anthonomus eugenii) is at work. The female lays eggs inside buds, and the larva eats them from within, causing flowers and ovaries to fall (Russo, 2012; Welbaum, 2015).
• Fruits ripen prematurely (turn red or yellow) but remain small and deformed. There may be barely visible brown spots or dots on the fruits. This is also the work of the weevil or the pepper maggot (Zonosemata electa), whose larvae develop inside the fruit, tunneling and causing rot (Russo, 2012).
• Fruits show small, corky (“cork-like”) holes, and when cut open, larvae or frass are found inside. This is characteristic of the European corn borer (Ostrinia nubilalis) caterpillars, which enter the fruit under the calyx and eat the flesh and seeds (Russo, 2012).
• Tunnels and larvae are found inside stems or fruits. This could also be cutworm or borer caterpillars that penetrate the stem, causing wilting and death (Russo, 2012).
• The plant suddenly wilts, even with adequate watering. This may result from root damage by wireworms or chafer grubs, which gnaw the root system (Kemble, 2022).

Tip: To diagnose hidden pests, be especially observant: inspect fruits and stems for the tiniest holes or dots, and watch for premature wilting and dropping of ovaries.

In the next chapter, we will examine in detail the most common sucking pests – aphids, whiteflies, and spider mites – and learn how to identify them correctly.

2.1 Aphids

Aphids are the most frequent visitors on peppers. They are small (1–3 mm) soft-bodied insects with pear-shaped bodies. They can be green, yellow, pink, or black. On peppers, the green peach aphid (Myzus persicae) and the cotton (melon) aphid (Aphis gossypii) are most common (Rêgo et al., 2016; Russo, 2012). Aphids live in colonies on the undersides of leaves, young shoots, and buds.

How to detect them? Aphid colonies are easily visible to the naked eye. But besides the insects themselves, there are characteristic signs:

• Leaves curl and deform, especially young ones (Russo, 2012).
• Sticky, shiny honeydew on leaves and fruits – the sugary excretions of aphids.
• Black sooty mold – the honeydew hosts sooty fungus (Rêgo et al., 2016).
• Ants crawling on plants – they feed on honeydew and “herd” aphids, protecting them from predators.

Why are they dangerous? Aphids not only weaken plants by sucking sap. The main threat is that they transmit viruses such as Cucumber Mosaic Virus (CMV), Potato Virus Y (PVY), and Tobacco Mosaic Virus (TMV). The virus is transmitted within seconds of a probe, and infected plants cannot be saved (Rêgo et al., 2016; Bosland and Votava, 2012).

How to control?

1. Biological method: Aphids are a favorite food of ladybugs, lacewings, and hoverflies. If these predators are present in your garden, hold off on insecticides. Attract them by planting flowering nectar plants (dill, phacelia, mustard) (Rêgo et al., 2016).

2. Mechanical method: For small infestations, wash aphids off with a strong jet of water (especially effective on young plants) or remove heavily infested leaves.

3. Biopesticides and home remedies: In organic farming, use soap solution (50 g of laundry soap per 10 L of water), garlic, onion, or hot pepper infusions. Effective biopesticides include insecticidal soap (M-Pede) and oil emulsions (e.g., paraffinic oil) (Kemble, 2022).

4. Chemical method: When economic thresholds are exceeded (see Chapter 6), apply systemic insecticides (imidacloprid, thiamethoxam) or contact ones (acetamiprid). But remember: they also kill beneficial insects, so use them only as a last resort and strictly according to the label (Kemble, 2022; Russo, 2012).

2.2 Whiteflies

Whiteflies are small (1–2 mm) insects with white, mealy wings. On peppers, the greenhouse whitefly (Trialeurodes vaporariorum) and the silverleaf whitefly (Bemisia tabaci) are most common. Adults typically stay on the underside of leaves and take off in a white cloud when the plant is disturbed (Rêgo et al., 2016; Russo, 2012).

How to detect them? Main signs:

• Sticky honeydew and sooty mold – as with aphids.
• Whitish, yellowish spots on leaves – feeding punctures.
• Nymphs – translucent, flat, scale-like, attached to the underside of leaves.
• Adults – easily seen when shaking the plant.

Why are they dangerous? Like aphids, whiteflies are vectors of dangerous viruses (e.g., Tomato Yellow Leaf Curl Virus (TYLCV) and other begomoviruses), which can be devastating for peppers. Heavy infestation weakens plants and significantly reduces yield (Rêgo et al., 2016; Kemble, 2022).

How to control? Whiteflies are harder to control than aphids because they are more resistant to many insecticides. An integrated approach:

1. Biological method: The main natural enemy is the parasitoid wasp Encarsia formosa, which lays eggs in whitefly nymphs, killing them. Predatory mites Amblyseius swirskii and fungal products based on Beauveria bassiana are also effective (Rêgo et al., 2016; Kemble, 2022).

2. Traps: Yellow sticky traps help monitor adult emergence and partially reduce numbers (Kemble, 2022).

3. Mechanical method: On small plots, remove and destroy leaves with many nymphs.

4. Chemical method: Use insecticides with different modes of action (e.g., buprofezin, pyriproxyfen, spirodiclofen) – they target nymphs, not adults. Rotate products from different groups to avoid resistance (Kemble, 2022; Russo, 2012).

2.3 Spider Mite (Spider mite)

The spider mite is not an insect but an arachnid (related to spiders). On peppers, the two-spotted spider mite (Tetranychus urticae) is most common. It is a very tiny pest (<0.5 mm) that lives in colonies on the underside of leaves, covering them with fine webbing (Rêgo et al., 2016; Russo, 2012).

How to detect it? Signs of infestation:

• Tiny pale dots (punctures) on the upper leaf surface – initially they look like a “marbled” pattern, then the leaf turns completely yellow and dries up (Rêgo et al., 2016).
• Fine webbing on the underside of leaves and between stems – under heavy infestation, the webbing becomes clearly visible (Kemble, 2022).
• Silvery or bronze tint on fruits – when heavily colonized (Russo, 2012).
• Presence of mites – can be seen with a magnifying glass or by shaking a leaf over white paper. They look like tiny, fast-moving dots.

Why are they dangerous? Spider mites do not transmit viruses, but their rapid reproduction makes them extremely dangerous. Up to 10 generations can occur in a season. Severely infested plants lose leaves, leading to a sharp drop in yield and even plant death. They are especially active in hot, dry weather (Rêgo et al., 2016; Bosland and Votava, 2012).

How to control? Spider mite control requires a special approach because they quickly develop resistance to acaricides.

1. Biological method: The main enemies are predatory mites of the family Phytoseiidae (e.g., Amblyseius herbicolus, Phytoseiulus persimilis). They effectively suppress spider mite populations. Avoid broad-spectrum insecticides that kill these predators (Rêgo et al., 2016; Kemble, 2022).

2. Increase humidity: Regular watering and misting (especially in hot weather) create unfavorable conditions for mites, which prefer dryness (Bosland and Votava, 2012).

3. Biopesticides: Use sulfur products (caution: above 30 °C they may cause burns), insecticidal soap, oil emulsions, and products based on the fungus Beauveria bassiana (Kemble, 2022).

4. Chemical method: Apply specific acaricides (abamectin, bifenazate, etoxazole, etc.). Rotate products with different modes of action to avoid resistance. Treat only local hotspots, not the entire field (Kemble, 2022; Russo, 2012).

Comparative Table of Sucking Pests

Important addition: All three pests not only weaken plants but also create favorable conditions for fungal diseases (sooty mold on honeydew, necrosis on damaged leaves). Therefore, timely detection and integrated control are key to pepper health.

In the next chapter, we will look at pests that attack flowers and ovaries – thrips and weevils – and learn how to save your future harvest from their attacks.

3.1 Thrips

Thrips are tiny (only 1–2 mm) insects with elongated bodies, barely visible to the naked eye. They feed on plant sap, but their main danger lies elsewhere – they are the primary vectors of Tomato Spotted Wilt Virus (TSWV), which can be lethal for peppers (Kemble, 2022; Rêgo et al., 2016). Thrips are especially active in hot, dry weather and prefer to hide inside flowers and under fruit calyxes (Russo, 2012).

Signs of damage:

1. Deformation and dropping of flowers and ovaries. This is the earliest and main sign. Damaged buds fail to open, flowers dry up and fall, and young ovaries stop developing and drop off (Rêgo et al., 2016).

2. Silvery or bronze discoloration on fruits. When feeding, thrips suck sap from epidermal cells, producing characteristic discoloured spots with a silvery sheen. These spots may be covered with tiny black dots (frass) (Kemble, 2022).

3. Deformation of young leaves. In early stages, before flowering, thrips may attack growing points, causing curling and deformation of young leaves, which become stiff and brittle.

4. Presence of thrips themselves. Tap flowers over a white sheet of paper; the dark, fast-moving dots that fall out are thrips.

How and when to control?

• Monitoring: The most effective way is to regularly tap flowers over a white sheet. If you find 2–3 thrips per flower, it is time to start protective measures (Kemble, 2022).
• Protection: In regions where TSWV is prevalent, it is best to plant virus-resistant varieties. Reflective (silver) mulch is also effective, as it disorients insects (Kemble, 2022; Rêgo et al., 2016).
• Biological control: Predatory bugs Orius (flower bugs) are natural enemies of thrips. Attract them by planting nectar-rich plants (e.g., dill, phacelia) (Rêgo et al., 2016).

3.2 Pepper Weevil (Anthonomus eugenii)

This pest is a real scourge for peppers in warm regions (Russo, 2012). The adult weevil is a small (about 3 mm) brown or greyish beetle with a characteristic “snout.” Both adults and larvae are damaging. The larva lives and feeds inside the bud or young fruit, completely hollowing it out. This pest often arrives on fields with infested transplants (Kemble, 2022).

Signs of damage:

1. Massive bud and ovary drop. This is the main and most noticeable symptom. Buds and tiny ovaries turn yellow and fall, and you can find many such fallen parts on the ground under the bush (Russo, 2012; Welbaum, 2015).

2. Puncture marks on fruits. Females lay eggs by drilling holes in young fruits. These holes quickly heal and appear as small brown or black dots.

3. Premature fruit ripening. Fruits infested with larvae often turn red or yellow much earlier than normal, remaining small and inedible.

4. Presence of adult beetles. They can be found in the morning or evening by inspecting buds and leaves. Yellow sticky traps are an excellent monitoring tool (Kemble, 2022; Russo, 2012).

How and when to control?

• Prevention: Use only healthy, certified transplants. Destroy all crop residues after harvest, as weevils overwinter in them.
• Monitoring: Regularly inspect buds and use yellow sticky traps. The most effective control is to apply insecticides when adult beetles first appear, before females lay eggs inside buds (Kemble, 2022).

3.3 Pepper Maggot (Zonosemata electa)

This pest is a true specialised “terrorist” of peppers. The adult fly lays eggs directly into the fruit flesh, and the hatched larvae (maggots) bore winding tunnels, causing rot (Russo, 2012). Sweet and hot peppers with thin walls suffer especially.

Signs of damage:

1. Dents and spots on fruits. Puncture sites from oviposition turn into small, sunken brown spots.

2. Premature ripening and rotting of fruits. Damaged fruits often rot from the inside, becoming soft and watery. Wet spots may appear.

3. “Wormholes” inside the fruit. Cut open an affected fruit to see winding tunnels and whitish larvae (Russo, 2012; Kemble, 2022).

How and when to control?

• Prevention: Thoroughly remove and destroy all damaged and dropped fruits. Adult flies are attracted to the smell of rotting fruit.
• Traps: Use yellow sticky traps with a small amount of ammonia (as an attractant) for monitoring. Place traps at an elevated level, at tree canopy height (Russo, 2012).
• Protection: An effective method is to plant “trap crops” (e.g., pepper varieties especially attractive to the fly) around the field perimeter and treat them with insecticide. This diverts flies from the main crop.

3.4 European Corn Borer (Ostrinia nubilalis)

Although this pest is more associated with corn, it is one of the most dangerous pests of sweet peppers in temperate regions (Russo, 2012). Corn borer caterpillars bore tunnels in stems and fruits of pepper. They usually enter the fruit at the stem attachment point, under the calyx, making it unfit for consumption.

Signs of damage:

1. Sudden wilting of the plant or parts of it. If the caterpillar tunnels the main stem, it disrupts nutrient flow, causing wilting.

2. Holes at the fruit base. Brown, “sawdust-like” frass (caterpillar feces) appears at the fruit stem (Russo, 2012).

3. Presence of caterpillars inside stems or fruits. Pinkish or cream caterpillars up to 2.5 cm long can be found inside.

4. Damaged leaves. Young caterpillars may first feed on leaves, leaving “windowpane” damage (skeletonization).

How and when to control?

• Prevention: Autumn ploughing and destruction of plant residues (corn stalks, weeds) help reduce overwintering caterpillar numbers.
• Monitoring: Use pheromone traps to track the start of moth flight. When traps show activity, start inspecting plants for egg masses on the underside of leaves.
• Protection: The main strategy is to spray insecticides during the peak egg hatch period. Once the caterpillar has entered the fruit or stem, control is impossible (Russo, 2012; Rêgo et al., 2016).

In the next chapter, we will move to “underground” pests that attack the root system and can invisibly ruin the entire harvest.

4.1 Wireworms

Wireworms are the larvae of click beetles. They are hard, shiny, yellowish-brown worms 1 to 4 cm long, living in the soil for 2 to 5 years. They are very mobile and can move through soil in search of food. Wireworms are especially common in plots previously occupied by perennial grasses (lawns, pastures) or cereal crops (corn, wheat) (Kemble, 2022; Bosland and Votava, 2012). They gnaw roots and bore into stems at the base and into roots.

Signs of damage:

1. Sudden wilting or stunted growth. Young plants may simply dry up, even with adequate watering, because their root system is damaged.

2. Torn or eaten roots. When digging up the plant, you can see that the roots are gnawed, with ragged edges.

3. Tunnels and holes in roots and stems. Wireworms can bore into stems, especially at the base, and into root crops (e.g., potato, but on pepper they more often damage roots).

4. Presence of larvae. They can be found in the top 10–20 cm of soil, especially at root depth. A good detection method is to bury pieces of raw potato or beet 5–10 cm deep and check them after a few days (Bosland and Votava, 2012; Kemble, 2022).

How and when to control?

• Prevention: Deep ploughing in autumn and spring destroys tunnels and some larvae. Crop rotation with non-host crops (legumes, buckwheat) reduces numbers. Controlling weeds, especially couch grass, deprives click beetles of extra food (Bosland and Votava, 2012).
• Traps: Place baits of potato, carrot, or beet pieces in the soil; collect them with the pests after 2–3 days. This is effective on small plots.
• Biological methods: Applying entomopathogenic nematodes (e.g., Heterorhabditis bacteriophora) to the soil is an effective biological control method in organic farming (Kemble, 2022).

4.2 Mole Crickets

Mole crickets are large (up to 5 cm or more) insects that live in the soil. They have powerful digging forelimbs resembling those of a mole. Mole crickets feed on both plant and animal matter. They are especially active in moist soil and can cause great damage to seedlings by cutting stems at the base and gnawing roots (Bosland and Votava, 2012; Kemble, 2022).

Signs of damage:

1. Massive death of young seedlings. Plants may simply fall over, as if cut off at ground level.

2. Tunnels and burrows in the soil. Mole crickets make horizontal tunnels just below the soil surface, especially noticeable after watering or rain. These tunnels appear as raised ridges.

3. Damaged roots and stems. Roots and stems appear gnawed, with ragged edges.

How and when to control?

• Prevention: Deep digging in spring and autumn destroys nests and tunnels. Early planting of seedlings, before mole crickets become active, can reduce damage (Swiader, 1992).
• Traps: In autumn, dig small pits (30–40 cm deep) and fill them with manure or compost. Mole crickets gather there for winter. In spring, check these pits and destroy the pests.
• Repellents: Mole crickets dislike the smell of certain plants (chrysanthemums, marigolds, garlic). Plant them around bed perimeters or use infusions of these plants for soil watering (Bosland and Votava, 2012).
• Biological methods: As with wireworms, entomopathogenic nematodes are effective.

4.3 Chafer Grubs (May Beetle Larvae) and Other Scarab Beetle Larvae

These are thick, fleshy, white or yellowish larvae with brown heads, living in the soil and feeding on plant roots. They are especially dangerous to young pepper plants. Their life cycle can last 3–4 years (Bosland and Votava, 2012; Kemble, 2022). They are most common on plots previously under turf or pasture.

Signs of damage:

1. Wilting, yellowing, and stunting. The plant gradually declines, its leaves yellow, and growth slows. If you dig up such a plant, you may find that its root system is severely damaged or completely eaten.

2. Presence of larvae. When digging, you can find thick, white, C-shaped larvae.

3. Damaged roots. Roots are gnawed, with ragged edges.

How and when to control?

• Prevention: Deep digging and hand-picking of larvae, especially in spring when they move closer to the surface.
• Attract natural enemies: Starlings, rooks, and other birds are active predators of chafer grubs. Attracting them to the plot is good prevention.

General preventive measures against soil pests:

1. Crop rotation: Avoid planting peppers and other solanaceous crops (tomatoes, potatoes, eggplants) in the same place for several years in a row. Soil pests specialised to these crops can build up high numbers (Rêgo et al., 2016).

2. Adding organic matter: Regular addition of quality compost or well-rotted manure improves soil structure and promotes beneficial microorganisms that can suppress pests (Kemble, 2022).

3. Biopesticides: Applying soil treatments based on entomopathogenic nematodes (e.g., Heterorhabditis and Steinernema) is a modern and safe way to control a complex of soil pests at any crop stage (Kemble, 2022).

4. Proper watering: Avoid overwatering, as it creates favourable conditions for mole crickets and other moisture-loving pests (Bosland and Votava, 2012).

Remember: detecting soil pests is not only a signal to fight them but also a reason to review your agronomic practices. Improving soil structure and health is the best long-term strategy for root protection.

In the next chapter, we will look at environmentally friendly pest control methods – biological control and traps – that help reduce chemical use.

5.1 Entomophages: Allies in the Battle for the Harvest

Entomophages are organisms that feed on other insects. They can be divided into two large groups: predators (kill many prey during their lifetime) and parasitoids (develop inside or on one host, eventually killing it). Attracting and preserving these beneficial creatures on your plot is the foundation of biological protection.

5.2 Traps: Monitoring and Capture

Traps are an important tool not only for catching but also for monitoring (observing) pest appearance. They help you notice danger in time and take action before the pest population reaches a critical level.

1. Yellow sticky traps: These are bright yellow plastic sheets coated with non-toxic glue. They effectively attract aphids, whiteflies, thrips, leafminer flies, and other small flying insects. Yellow colour acts as a visual attractant. Place several traps around the plot perimeter or inside beds at plant height (Kemble, 2022; Russo, 2012).

• Why for the gardener: Traps show when mass flights begin. This signals the need for increased inspections and protective measures. Check and replace traps regularly as they fill up.
• Blue sticky traps: Some data suggest that blue colour is particularly attractive to thrips. They can be used alongside yellow traps for better monitoring (Kemble, 2022).
• Pheromone traps: These are special traps that use a synthetic sex pheromone (scent) of females of a specific insect species to attract males. They are highly specific and used to monitor particular pests: European corn borer, pepper weevil, cutworms, and to track flight timing. For example, corn borer traps help determine when to start treatments against caterpillars (Bosland and Votava, 2012; Russo, 2012). Pheromone traps are usually more expensive but very effective for precise spray-timing decisions.
• Food baits (attractant traps): These traps use food odours to attract pests. For pepper maggot, use yellow traps with a little ammonia. For wireworms and mole crickets, bury pieces of raw potato or manure pits in the soil. Such traps serve both monitoring and partial capture (Russo, 2012; Kemble, 2022).
• Trap crops: These are not exactly traps, but a tactical approach. Planting plants that are more attractive to the pest than the main crop. For example, mustard or radish attract flea beetles, while peppers around the field perimeter attract pepper weevils. Pests concentrate on trap crops, where they can be treated with insecticide or simply destroyed, protecting the main crop (Russo, 2012; Rêgo et al., 2016).

Conclusion: Biological control is not an alternative but an important part of integrated pest management. Combining knowledge of pests, their natural enemies, and simple monitoring tools allows you to significantly reduce chemical use and produce environmentally friendly pepper harvests.

In the final chapter, we will discuss the most complex issue – when exactly does a pest become economically dangerous, and why “just in case” spraying often backfires.

6.1 Why Is “Just in Case” Spraying a Bad Idea?

Many gardeners have a habit of spraying plants “against everything” on a calendar schedule. This is a mistake that leads to three negative consequences:

1. Destruction of natural enemies. Broad-spectrum insecticides kill not only pests but also the predators and parasitoids that keep them in check. This leads to pest (especially aphids and spider mites) rebounding with renewed vigour, as their enemies are gone (Kemble, 2022; Russo, 2012).

2. Development of resistance. The more often you use the same product, the faster pests develop resistance. You end up with a population of “super-pests” that are impossible to control (Rêgo et al., 2016; Kemble, 2022).

3. Waste of time and money. Treatment when the pest is not yet a threat does not pay off. You spend money, time, and harm the environment without real need.

6.2 How to Determine the Economic Threshold for Major Pepper Pests?

Specific numbers may vary depending on the region, crop stage, and variety, but there are general guidelines to help you make decisions.

Aphids (Aphids):

• Guideline: Carefully inspect the undersides of leaves and shoot tips. Take action if 50% or more of plants have 5 or more aphids per leaf or shoot, and the population is clearly increasing (Kemble, 2022).
• Why: Small aphid colonies can be wiped out by ladybugs and other predators. Intervention is justified when aphids start multiplying rapidly, causing leaf curl and abundant honeydew (leading to sooty mold). Also, aphids are virus vectors, so in regions with high virus pressure the threshold may be lower (Rêgo et al., 2016).

Spider mite (Spider mite):

• Guideline: Inspect leaves (especially undersides) for pale spots (punctures) and fine webbing. Start treatments when 10–15% of leaves in the upper part of the bush are infested early in the season, and 50% in mid‑ or late season (Kemble, 2022; Russo, 2012).
• Why: Spider mites multiply very quickly in hot, dry weather. If you miss the moment, they can destroy the leaf canopy in 1–2 weeks. Treat only local “hot spots”, not the whole area, to preserve predatory mites (Rêgo et al., 2016).

Thrips (Thrips):

• Guideline: The most reliable method is tapping flowers over a white sheet. The economic threshold for many regions is 2–3 thrips per flower (Kemble, 2022; Rêgo et al., 2016).
• Why: Thrips not only damage ovaries but also transmit Tomato Spotted Wilt Virus (TSWV), which can destroy the entire crop. Once thrips appear in flowers, start monitoring and apply protection when the threshold is reached. In high TSWV‑risk areas, plant resistant varieties from the start.

Caterpillars (cutworms, borers):

• Guideline: Inspect leaves for damage and caterpillars. For European corn borer on sweet pepper, the threshold is 1 caterpillar per 10 plants or fresh damage on 15% of plants (Kemble, 2022; Russo, 2012). For cutworms on tomatoes and peppers – 1 caterpillar per 6 plants.
• Why: Young caterpillars are most vulnerable, and treatment at that time is most effective. Once a caterpillar has entered the fruit or stem, it cannot be saved. So it is crucial to catch the peak egg‑hatch period.

Pepper weevil (Pepper Weevil):

• Guideline: Use yellow sticky traps to monitor adult beetles. The threshold is 1 beetle per 400 buds or 1% damaged buds (Kemble, 2022; Russo, 2012).
• Why: The weevil is one of the most dangerous pests. Missing its appearance can cost you most of the fruit set. Treatment must begin immediately after adult beetles are detected, before females lay eggs inside buds.

Soil pests (wireworms, mole crickets):

• Guideline: For them, the threshold is harder to determine visually. The main method is pre‑planting diagnosis. If there were problems last year, or if you find more than 5–10 larvae per 1 m² during digging, risk is high. Use potato‑piece traps and check them (Bosland and Votava, 2012).
• Why: Losses from soil pests are especially critical for seedlings. A young plant can be destroyed in a few days. Prevention is more important than cure here.

6.3 Factors Influencing the Decision to Start Control

Economic thresholds are not dogma, but guidelines. Additional factors influence the decision:

1. Plant growth stage. Young seedlings and plants at flowering and fruit‑set are most vulnerable and less tolerant of damage. The threshold should be lower for them. Mature, well‑developed bushes can tolerate some pests without significant yield loss (Rêgo et al., 2016; Welbaum, 2015).

2. Weather conditions. Hot, dry weather favours spider mites and thrips. Periods of rain and coolness reduce their activity but may promote fungal diseases on damaged tissues (Bosland and Votava, 2012).

3. Presence of natural enemies. If you have many ladybugs, lacewings, or predatory mites on your plot, you can allow the pest population to be slightly above the threshold, as the entomophages may cope on their own. Regularly inspect plantings and assess the pest‑predator ratio (Rêgo et al., 2016).

4. Plant variety. Some pepper varieties are more resistant to certain pests or diseases. Use this information when choosing varieties for planting (Kemble, 2022).

Practical tip: Keep an observation diary. Record when you first noticed pests, how fast their numbers grew, what weather conditions favoured them. Over time, you will develop an intuitive sense of when to intervene and when to wait.

Main takeaway: Successful pepper pest protection is not a war but management. The gardener’s goal is not to eliminate all pests (that is impossible and unnecessary), but to keep their populations below the economic threshold while preserving beneficial insects and plant health.

This concludes our series of articles. Armed with knowledge of damage types, specific pests, biocontrol methods, and economic thresholds, you will be able to make informed and effective decisions to protect your pepper harvest.