Common Garden Pests & How to Deal With Them
| Pest | What They Attack | Signs of Damage | Control Methods |
|---|---|---|---|
| Aphids | Most vegetables, flowers, herbs | Sticky residue (honeydew), curled/yellowing leaves | Spray with insecticidal soap, neem oil, or blast with water; attract ladybugs |
| Cabbage Worms (imported cabbageworm, cabbage looper) | Broccoli, cabbage, kale, Brussels sprouts | Holes in leaves, green droppings | Handpick, use Bt (Bacillus thuringiensis), cover with row covers |
| Cutworms | Young seedlings (especially tomatoes, lettuce) | Plants cut off at the soil line | Use collars around stems, keep garden clean of debris |
| Tomato Hornworms | Tomatoes, peppers, eggplant | Large bite marks, leaf stripping, green poop | Handpick, use Bt or spinosad, attract parasitic wasps |
| Slugs & Snails | Lettuce, spinach, strawberries, hostas | Ragged holes in leaves, slime trails | Use beer traps, copper tape, diatomaceous earth, or handpick at night |
| Squash Bugs | Squash, zucchini, pumpkins | Wilting, yellow/brown patches, eggs on leaf undersides | Remove eggs, use neem oil or insecticidal soap, trap with boards |
| Spider Mites | Tomatoes, beans, cucumbers | Yellow speckling on leaves, webbing | Spray with water, use insecticidal soap, encourage predatory mites |
| Whiteflies | Leafy greens, cucurbits, tomatoes | Tiny white bugs, yellowing leaves, sticky residue | Yellow sticky traps, neem oil, insecticidal soap |
| Flea Beetles | Radishes, eggplant, tomatoes, leafy greens | Small holes (“shotgun” damage) in leaves | Use floating row covers, diatomaceous earth, neem oil |
| Leaf Miners | Beets, spinach, chard | Winding, white tunnels inside leaves | Remove affected leaves, use row covers, neem oil spray |
| Colorado Potato Beetles | Potatoes, eggplant, tomatoes | Defoliation, orange/yellow beetles with stripes | Handpick, use spinosad or neem oil, rotate crops |
| Japanese Beetles | Beans, roses, fruit trees | Skeletonized leaves, shiny green beetles | Handpick, use traps far from garden, neem oil spray |
| Thrips | Onions, garlic, flowers, tomatoes | Silvery streaks on leaves, distorted growth | Insecticidal soap, neem oil, blue sticky traps |
Natural & Organic Pest Control Options
- Neem oil – disrupts insect hormones; works on soft-bodied insects
- Bt (Bacillus thuringiensis) – natural bacteria for caterpillar pests
- Insecticidal soap – suffocates pests like aphids and mites
- Row covers – physical barrier to prevent pest access
- Companion planting – basil repels thrips; marigolds deter nematodes
- Encourage beneficial insects – ladybugs, lacewings, parasitic wasps
Types of Insecticides
There are several types of insecticides, each classified by their mode of action, source (chemical or natural), or target pests. Here’s a breakdown of the main types gardeners should know:
1. Chemical (Synthetic) Insecticides
These are lab-manufactured compounds designed to kill or repel insects quickly.
| Type | Example Ingredients | Common Uses | Pros | Cons |
|---|---|---|---|---|
| Pyrethroids | Permethrin, Cypermethrin | General use on flowers, vegetables | Fast-acting, broad-spectrum | Harmful to bees & aquatic life; short residual |
| Organophosphates | Malathion, Diazinon | Fruits, vegetables, ornamentals | Effective against a wide range of pests | Toxic to humans/pets; banned/restricted in some areas |
| Carbamates | Carbaryl (Sevin) | Vegetables, lawns | Kills chewing and sucking insects | Harmful to beneficial insects; resistance possible |
| Neonicotinoids | Imidacloprid, Acetamiprid | Soil/systemic use on ornamentals | Long-lasting, systemic protection | Harmful to bees; restricted in many regions |
2. Organic/Natural Insecticides
Derived from natural sources (plants, bacteria, minerals). Generally safer for humans, pets, and beneficial insects if used properly.
| Type | Source | Effective Against | Notes |
|---|---|---|---|
| Neem Oil | Neem tree seeds | Aphids, whiteflies, spider mites, beetles | Disrupts insect hormones; also fungicidal |
| Insecticidal Soap | Fatty acids from plants | Aphids, mites, thrips | Works by suffocating; must directly contact pest |
| Diatomaceous Earth | Fossilized algae (silica) | Crawling insects (ants, beetles, slugs) | Cuts exoskeletons; safe for pets when food-grade |
| Pyrethrin | Chrysanthemum flowers | Broad range (fast knockdown) | Short-lived; degrade quickly in sunlight |
| Bt (Bacillus thuringiensis) | Soil bacteria | Caterpillars, mosquito larvae | Selective; safe for beneficials & humans |
| Spinosad | Soil bacterium (Saccharopolyspora) | Thrips, leafminers, caterpillars | Organic-approved; toxic to bees when wet |
| Horticultural Oils | Mineral or vegetable oils | Scale, aphids, mites | Smothers pests; safe when used properly |
| Garlic or Pepper Sprays | Homemade or commercial | Repels soft-bodied insects | Less effective than others; short-lived |
3. Systemic vs. Contact Insecticides
| Type | How It Works | Examples |
|---|---|---|
| Contact | Kills insects on direct contact | Insecticidal soap, pyrethrin, neem oil |
| Systemic | Absorbed by the plant and ingested by feeding pests | Imidacloprid, spinosad (partially systemic), neem oil (mildly systemic) |
Pollinator-Safe Tips
- Spray early morning or evening when bees aren’t active
- Choose targeted, non-residual products (e.g., Bt, insecticidal soap)
- Avoid blooming plants when applying any insecticide
Comparison of insecticide products
Insecticide Product Comparison Chart (Garden Use)
| Product Name | Type | Active Ingredient | Effective Against | Safe for Edibles | Bee Safe | Notes |
|---|---|---|---|---|---|---|
| Neem Oil (e.g., Garden Safe Neem) | Organic/Natural | Azadirachtin + oil extract | Aphids, mites, whiteflies, beetles | ✅ Yes | ⚠️ When dry | Fungicide too; avoid spraying during pollinator activity |
| Captain Jack’s Deadbug Brew | Organic/Natural | Spinosad | Caterpillars, thrips, leafminers, fire ants | ✅ Yes | ⚠️ Toxic when wet | OMRI-listed; great for organic vegetables |
| Safer Insecticidal Soap | Organic/Natural | Potassium salts of fatty acids | Aphids, whiteflies, mites, mealybugs | ✅ Yes | ✅ Yes | Contact only; spray directly on pests |
| Bonide Pyrethrin Garden Insect Spray | Organic/Natural | Pyrethrins | Most soft-bodied insects | ✅ Yes | ⚠️ Toxic if bees are exposed | Quick knockdown; short residual |
| Diatomaceous Earth (Food Grade) | Organic/Natural | Fossilized diatoms (silica) | Slugs, beetles, ants, earwigs | ✅ Yes | ✅ Yes | Apply dry; avoid breathing dust |
| Bt (e.g., Thuricide) | Organic/Natural | Bacillus thuringiensis | Caterpillars (tomatoes, cabbage, etc.) | ✅ Yes | ✅ Yes | Harmless to humans, pets, bees; very specific |
| Sevin (Carbaryl) | Synthetic | Carbaryl | Wide range (beetles, worms, aphids) | ⚠️ Check label | ❌ No | Long-lasting but kills beneficials; banned in some areas |
| Ortho Bug B Gon | Synthetic | Bifenthrin, zeta-cypermethrin | Many pests (incl. ants, beetles, caterpillars) | ⚠️ Edibles version available | ❌ No | Powerful, broad-spectrum; not pollinator-safe |
| BioAdvanced Fruit & Vegetable Insect Control | Synthetic/Systemic | Imidacloprid | Sucking insects (aphids, whiteflies) | ✅ Yes (label use) | ❌ No | Systemic; avoid during bloom |
Best Choices by Use Case
| Need | Recommended Product(s) |
|---|---|
| Organic Garden All-Purpose | Neem Oil, Captain Jack’s, Insecticidal Soap |
| Caterpillar Control | Bt (Thuricide), Spinosad (Captain Jack’s) |
| Pollinator-Friendly Garden | Bt, Insecticidal Soap, Diatomaceous Earth (careful application) |
| Heavy Infestation (Non-organic OK) | Ortho Bug B Gon, Sevin (limited, last resort) |
| Low Toxicity to Pets & People | Neem, Soap, Bt, Diatomaceous Earth |
Important Notes:
- Always read the label to confirm whether a product is safe for edible crops and how it affects beneficial insects.
- For bee safety, apply sprays in the evening or early morning, and never on flowers in bloom.
- Rotate active ingredients to avoid pest resistance over time.