27 Destructive Garden Pests and How to Get Rid of Them

A thriving garden can quickly turn into a battleground when pests invade. From tiny sap-sucking aphids to destructive caterpillars and beetles, these unwelcome guests can damage plants, stunt growth, and ruin crops. The key to protecting your garden is knowing what to look for and how to fight back. This guide will help you identify the most common garden pests, recognize the signs of damage, and use effective, eco-friendly methods to keep them under control.

Aphids (Greenfly, Blackfly)

Appearance: These tiny, soft-bodied pests are among the most common garden nuisances, impacting plant growth by sucking sap. While typically green or black, aphids can also appear in shades of orange, brown, or pink. They cluster on soft stems and under leaves, leaving behind a sticky residue known as honeydew. Ants often farm aphids, so spotting ants on stems may indicate an infestation.

Key Signs of Aphid Damage: Watch for curled, yellowed, or distorted leaves. A clear, sticky honeydew secretion can signal aphid presence, often leading to black sooty mold.

Favourite Plants to Consume: Aphids target a wide variety of plants, especially tender new shoots in both outdoor gardens and greenhouses.

Ways to Tackle: Natural predators like ladybugs, lacewing larvae, and hoverflies help control aphid populations. If infestations are minor, manually squashing them works. For larger outbreaks, gently shaking plants or rinsing aphids off with diluted dish soap can be effective.

Whitefly

Appearance: Whiteflies are tiny, white-winged insects resembling miniature moths, measuring just 1-2 mm. Related to aphids, they favor young leaves, often clustering on the undersides. When disturbed, they take flight in swarms. Their rapid three-week lifecycle makes infestations escalate quickly.

Key Signs of Whitefly Damage: These pests drain plant sap, weakening growth. While direct damage may not be obvious at first, severe infestations can lead to black sooty mold. Whiteflies thrive in greenhouses.

Favourite Plants to Consume: Found on various plants, including azaleas, rhododendrons, and honeysuckle, they also target edible crops like tomatoes, cucumbers, and cabbages.

Ways to Tackle: Yellow sticky traps effectively capture adult whiteflies in greenhouses. Companion planting, such as growing marigolds near susceptible plants, can help deter them due to their strong scent.

Slugs

Appearance: Recognizable by their soft, slimy bodies and retractable sensory tentacles, slugs move using a muscular foot. They vary in size from tiny to alarmingly large, with some species exceeding 20 cm.

Key Signs of Slug Damage: Look for irregular holes in leaves or scalloped edges where bites have been taken. Silvery slime trails near damaged plants confirm slug activity. Since they feed at night, fresh damage in the morning is a strong indicator. Smaller slugs often do the most harm, even more than the large ones seen on lawns.

Favourite Plants to Consume: These voracious pests devour almost anything, with a preference for tender leaves, vegetables, fruits, and salad crops.

Ways to Tackle: Attracting natural predators like hedgehogs, centipedes, and slow worms (if lucky) can help control slug populations. Some gardeners have success using copper barriers. Organic methods like Slug Gone Wool Pellets also provide an effective deterrent.

Cabbage Moth Caterpillar

Appearance: These caterpillars, known for damaging brassicas, are hairless and vary in shades of yellow or brownish-green. Unlike some other species, they burrow deep into cabbage heads, making them particularly destructive.

Key Signs of Cabbage Moth Caterpillar Damage: Visible holes in brassica leaves are the primary sign. In some cases, you may spot the caterpillars themselves.

Favourite Plants to Consume: They target cabbage, broccoli, Brussels sprouts, and other brassicas.

Ways to Tackle: Encouraging birds in your garden helps keep caterpillar numbers down. Covering brassicas with netting provides a physical barrier. Regularly inspecting and removing caterpillars and eggs by hand is another option. Planting marigolds nearby can repel cabbage white butterflies, but avoid placing them too close, as they can hinder cabbage root growth.