Garden pests: snails, ants, grasshoppers, rose chafers and stink bugs

Our garden pest series continues with snails, slugs, ants, grasshoppers, rose chafers and plant-feeding stink bugs. Not every visitor needs controlling: identify the organism, assess the damage and check whether the population is actually harming your plants before taking action.

Garden pests: identification and responsible management

11. Snails and slugs

These gastropod molluscs can feed on tender leaves, shoots, flowers and seedlings. They often leave irregular holes and shiny slime trails, which can help distinguish their damage from caterpillar feeding. They are especially active at night and in damp weather.

Many snails have a visible external shell; slugs have no obvious shell or only a reduced one. Not every gastropod in a garden causes significant harm, so check which plants are actually being eaten.

Prevention and monitoring

Look beneath pots, around raised-bed edges and in moist hiding places at dusk. Where practical, hand-pick snails and slugs that are damaging plants and reduce excessive shelter around vulnerable seedlings. Watering in the morning without waterlogging can make the surface less inviting to them.

Traps and barriers can help, but neither replaces regular monitoring. Plants and beneficial soil organisms still need suitable moisture; drying out the entire garden is not a sensible solution.

Traps, barriers and baits

A traditional beer trap uses a container buried with its rim near soil level. It may catch some slugs and snails, but it can also attract them from nearby. Check it daily and protect other animals from falling in. A board placed as a temporary shelter can make morning hand-collection easier.

Copper tape and bands are often sold as slug barriers, but RHS field trials found no reliable reduction in plant damage. Do not rely on copper alone. Crushed eggshells and coffee grounds have not proved reliable deterrents. Avoid putting salt on garden soil because it increases salinity.

If damage warrants a bait, check local approval and follow the label. Iron phosphate baits generally pose less risk than metaldehyde products, which can poison dogs and wildlife. Baits work best alongside shelter and moisture management.

12. Ants

Many ants benefit gardens by aerating soil, scavenging and preying on other invertebrates. Some species, however, protect Aphids, mealybugs, scale insects and whiteflies in exchange for their sugary honeydew, making it harder for natural enemies to control those pests. Other ants may occasionally damage plants directly or cause problems through stings.

Seeing ants on a plant does not automatically mean there is an infestation. Examine new growth and leaf undersides to find out what attracts them.

When ants protect sap-feeding pests

Start by reducing aphids or mealybugs using plant-appropriate methods, such as a moderate water spray or removing badly infested shoots. On trees, a sticky barrier applied over protective tree wrap, rather than directly onto sensitive bark, can keep ants away from honeydew-producing insects.

Lemon juice is a traditional way to disrupt ant trails, but its effect is temporary and it may damage foliage or bark; it is not a reliable way to eliminate a colony. If colony management is genuinely necessary, use locally approved enclosed baits away from children and pets. Do not scatter salt or broad-spectrum pesticides over garden soil.

13. Grasshoppers and locusts

These are plant-feeding orthopteran insects. Some grasshoppers chew foliage, but occasional individuals usually cause tolerable damage. The term locust refers to certain species that can develop dense, sometimes migratory swarms under particular conditions; not every grasshopper is a swarming locust.

Identify the insect, estimate its numbers and look for fresh feeding damage before intervening. Large outbreaks call for advice from local agricultural or plant-health authorities rather than improvised home treatments.

Proportionate measures

In small gardens, properly fitted netting can protect young plants. Check garden edges and hand-remove insects where feasible. Birds and other predators contribute to natural regulation, although they cannot be relied on to stop a major outbreak.

Hot-pepper or chilli sprays are traditional deterrents, but they can irritate skin and eyes, scorch foliage and affect non-target wildlife. They are neither universally effective nor harmless. Neem-based products differ in composition and effectiveness: use only formulations registered for the relevant pest and plant. Avoid brand-specific or routine insecticide recommendations without a confirmed diagnosis.

14. Rose chafer (Cetonia aurata)

The rose chafer is a metallic green beetle. Adults visit flowers for pollen and nectar and may sometimes eat flower parts. Large numbers can spoil blooms, but they seldom justify treatment in a home garden.

The larvae live in decomposing organic matter and help break it down in compost. They should not automatically be confused with the root-feeding grubs of other beetles. If adults are causing noticeable damage, identify them and hand-pick a few where practical. Avoid spraying insecticides onto flowers visited by pollinators.

15. Plant-feeding stink bugs: Nezara and relatives

Some shield bugs in the family Pentatomidae, including the southern green stink bug Nezara viridula, pierce leaves, stems or fruit with their sucking mouthparts. Depending on the crop and the size of the infestation, feeding can cause spots, distortion or damage to fruit. Not all shield bugs are pests: some species are useful predators.

Many release a strong odour when disturbed. Look beneath leaves for eggs and nymphs, and identify the species before removing egg clusters so that you do not destroy beneficial insects by mistake.

Managing stink bugs

In small gardens, inspect plants regularly and hand-remove identified plant-feeding stink bugs and, where practical, their eggs. Protect predators and parasitoids. Commercial insecticidal soaps labelled for plants may affect some exposed stages, but they are not the same as household washing-up liquid and are not effective against every stink bug.

Pyrethrum is a plant-derived insecticide with a history of use, but that does not make it selective or safe for pollinators and other insects. Consider a locally approved pesticide only when damage is significant and nonchemical measures are insufficient, following the product label.

A healthy garden is not an insect-free garden. The goal is to recognise each organism, distinguish tolerable feeding from a damaging outbreak and choose measures that protect plants and biodiversity alike. After intervening, check new growth to see whether your approach worked.

Have you encountered slugs, ants or stink bugs in your garden? Tell us what you noticed and what helped.

Technical review informed by UC IPM integrated pest management guidance and Royal Horticultural Society biodiversity advice. Always check the plant-protection regulations that apply where you live.