Sage and Ligurian Leafhoppers is a minor pest that affects sage, rosemary and lavender.
What does it look like?
Adults are up to 3.5mm long, pale green and heavily dappled with brown and black markings. Nymphs are creamy white and do not have fully formed wings. The discarded white skins often stay attached to the lower leaf surface, and the insects themselves are usually on the underside of the leaves.
What causes it
These leafhoppers don't favour one herb: they feed on sage, mints, lavender, bergamot, marjoram, oregano, rosemary, basil, thyme and lemon balm, all aromatic plants in the mint family. These are the herbs a keen gardener tends to plant side by side, so a population on one has neighbouring hosts to move onto.
Is this pest active now?
Active from April or May through to September or the autumn, with mottling building up as the season goes on and often heaviest by late summer. No month calls for different action from another, since tolerating it is the advice throughout.
Symptoms
Coarse pale spotting appears on the upper surface of the leaves and builds up as the insects feed through the season, so by late summer affected leaves may be heavily mottled. Growth is little affected even when the mottling looks extensive. Market growers care more, because retailers accept almost no damage on culinary herbs.
Life cycle
Eggs overwinterKeeping a plant alive and intact through the cold months, whether left outdoors, moved under cover, or stored dormant. Full definition → on the host plants and hatch as the weather warms. The nymphs shed their skin through five stages before becoming adults, and several generations a year have been reported from Europe.
Why this matters in Scotland
Damage and harvest barely overlap here: every herb affected is picked for its leaves, not grown for a fruit or flower that mottling could interrupt, which is why the risk is rated low.
Sage, rosemary, lavender, thyme, mint, oregano, basil and lemon balm are all common choices for a Scottish herb bed. Tolerating leafhoppers costs nothing beyond how the leaf looks. No Scottish survey of these leafhoppers was found, so the rating rests on the damage itself, not on Scottish conditions.
Controls: what works
Natural predators: encourage birds, ladybirds, wasps and ground beetles
Birds, ladybirds, wasps and ground beetles are the natural enemies to encourage; US extension advice also names lacewings and spiders. A garden with shelter for them does more here than any direct intervention would.
Tolerate cosmetic mottling on established plants
Leafhoppers often don't affect the growth or vigour of the plant, and affected herbs are safe to eat. Mottled leaves go when you harvest or cut a herb back, and new growth in the following season is unlikely to carry last year's marks.
Myths about sage and Ligurian leafhoppers
“Pale, coarse mottling on sage, lavender or rosemary leaves is a sign of viral infection or a nutrient deficiency, not an insect problem”
The coarse pale mottling gardeners see on sage, lavender, rosemary and other aromatic herbs is leafhopper feeding damage, not a virus or a nutrient problem. The insects are seen on the underside of the leaves, and the pale spotting builds up on the upper surface as they feed. Checking the underside of a mottled leaf for the pale green adults, creamy nymphs or a white cast skin confirms the insect as the cause.
Our read The mottling looks similar to some viral leaf symptoms, which is likely why the misdiagnosis is common in herb beds, but the insects on the underside explain it.
What to do: Turn a mottled leaf over and check for pale green adults, creamy nymphs or white cast skins before assuming disease or feeding a struggling plant.
1 source
- RHS: Sage and Ligurian leafhoppersDescribes coarse pale spotting on upper leaf surfaces, with the leafhoppers seen on the underside of leaves and discarded white skins on the lower surface.
“Heavy leafhopper mottling by late summer will stunt the plant's growth or weaken it going into next season”
Even when mottling is heavy by late summer, it seems to have little effect on the plant's growth, and leafhoppers often don't affect growth or vigour at all.
What to do: Leave heavily mottled foliage alone rather than cutting the plant back hard or treating it as stressed; harvesting and normal seasonal pruning remove the marked leaves anyway.
1 source
- RHS: Sage and Ligurian leafhoppersStates that affected leaves may be heavily mottled by late summer but that this seems to have little effect on plant growth, and that control isn't necessary.
“Herb leaves that are mottled from leafhopper feeding shouldn't be eaten”
Affected herbs stay safe to pick and eat despite the mottled appearance; the damage is cosmetic.
What to do: Pick and use mottled sage, rosemary, thyme or other affected herb leaves as normal.
1 source
- RHS: Sage and Ligurian leafhoppersConfirms that affected herbs are safe to eat despite the mottled leaves.
“A sage or lavender bed with leafhoppers needs spraying to bring the population under control”
No chemical control is recommended for this pair of species at all. The advice given instead is to tolerate the cosmetic mottling and encourage natural predators such as birds, ladybirds, wasps and ground beetles, which is sufficient given how little the damage affects the plant. A UK trial on commercial herb crops found that no treatment completely eliminated damage, and the standard it was working to was a retailer's near-zero tolerance, not a garden's.
What to do: Skip spraying, make the bed welcoming to predators, and accept cosmetic mottling on the leaves.
2 sources
- RHS: Sage and Ligurian leafhoppersGives no chemical control for these leafhoppers and recommends tolerating the damage while encouraging natural predators such as birds, ladybirds, wasps and ground beetles.
- AHDB: Sage advice for controlling leafhopper on herbsIn a trial on commercial herb crops none of the treatments completely eliminated damage, and retailers have almost zero tolerance of pests or damage.
Frequently asked questions
What should I do first if I find sage and Ligurian leafhoppers in my garden?
The first thing to try: Natural predators. Then: Tolerate cosmetic mottling on established plants.
Will sage and Ligurian leafhoppers kill my plants?
They rarely kill established plants. The damage is usually cosmetic on outer leaves, and natural predators often bring numbers under control without you doing anything.
When should I watch for sage and Ligurian leafhoppers?
Active from April or May through to September or the autumn, with mottling building up as the season goes on and often heaviest by late summer. No month calls for different action from another, since tolerating it is the advice throughout.
Should I just leave sage and Ligurian leafhoppers alone?
In most gardens, yes. Sage and Ligurian leafhoppers are food for birds, wasps and predatory insects, and a healthy garden carries some without trouble. Tolerance is also RHS's position, for that same reason.
Sources
Show the 3 sources
- RHS1: adult and nymph description, cast skins, ten host plants, coarse pale spotting on the upper leaf surface, heavily mottled by late summer with little effect on growth, safe to eat, overwintering as eggs, active April to September (quick facts) or May to autumn (text), tolerating it, encouraging birds, ladybirds, wasps and ground beetles, no chemical control given
- pubs.ext.vt.edu: stippling from feeding, five nymphal stages, several generations a year reported from Europe, eggs overwintering and hatching in spring, lacewings, lady beetles and spiders as beneficials, quality and yield loss on commercial herbs
- horticulture.ahdb.org.uk: retailers' near-zero tolerance of damage on culinary herbs, and no treatment completely eliminating damage in the trial